Catchweight

Storage & Organization showdown

The Best 300-Gallon Deck Boxes of 2026: Two Shells, Nine Labels, and the One Box Bigger Than Its Number

A wooden backyard deck with a folding table and chairs against a red house, one chair folded flat — the furniture a big deck box exists to put away
Photo: Trausti Evans, CC BY 2.0

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How we scored thisfull methodology →
contenders compared
5
owner ratings · Amazon
1,967
data last verified
October 2026

Search “320 gallon deck box” and Google finishes the sentence for you: Costco, Home Depot, Walmart, waterproof, brown, black. The demand is real. What is not real is most of the number. We read every 300-gallon-plus deck box on Amazon’s best-seller and new-release lists and three searches, signed in, on 17 September 2026, with the critical reviews read for each of the five we carded — and then we did the one thing no roundup does: we divided each box’s own listed dimensions by 231, the cubic inches in a gallon.

The class is two resin shells. One measures 67.72 × 32.2 × 33.66 inches on four different brands’ listings and holds 318 gallons of exterior volume; it is sold as 320, 330, 350 and 370. The other is about 58 × 32 × 34 inches, 272 gallons of exterior, sold as 300, 320 and 380. Only one box in the class is bigger than its label. That is the box we would buy, and its catches are printed below the buy button.

The short version:

🏆 Best overall — NUNU LAB 320: 75 inches long, the deepest base in the class (4.3★/1,182, pooled across 29 sizes and colours), and the only 300-plus claim that fits inside its own shell. $300. The catch: sold by a storefront named “Amzaon’”, and owners say wind can open the lid.

💸 Best value — ATMELT 300: currently unavailable on Amazon (re-read 2026-09-27: no seller offers it). When we carded it, $200, the highest Amazon best-seller rank of the five the day we read it, a support rod on the lid, and a shell within 2% of its label. 4.8★/64 — early data, two critical reviews, one of them “everything in there is soaked”.

🧱 Double-wall, sold by Amazon — YITAHOME 300: gas struts, double-wall panels, Amazon.com as the seller, $198. 4.1★/422 with 17% one- and two-star: broken parts in the box and a lid that warped in a year.

🔩 The metal one — MIRADOR 281: aluminum and steel, wheels, soft-close, a maker with a store and a warranty page, $599. 4.0★/88, 13% one-star, and the tail is bent panels and screw holes that do not line up.

⛔ SKIP — TARKARI 370: a 318-gallon shell with 370 on the front, from the seller who labels the identical shell 320 under the Yardgrace name. “It blew apart in a wind storm.”

Billed Catchweight — compared by the job, not by price. Ratings read live on Amazon, signed in, 17 September 2026.

How they compare

ModelBest forCapacityExterior volumeMaterialLidWarrantyPrice
NUNU LAB 320 Gallon Deck Box product photoNUNU LAB 320 Gallon Deck Box
Best overall (the only shell bigger than its label)320 gal (listing)376 gal (75.08 × 34.37 × ~33.7 in; the listing's own height field reads 6.69 in, a data error)Resin (listing)Piston-assisted, lockable (lock not included)Not publishedCheck price →
ATMELT 300 Gallon Deck Box with Support Rod product photoATMELT 300 Gallon Deck Box with Support Rod
Best value (the class's best-seller)300 gal (listing)294 gal (58.87 × 33.24 × 34.66 in)Polypropylene resin (listing)Support rod, lockable (padlock not included)Not publishedCheck price →
YITAHOME 300 Gallon Double-Wall Deck Box product photoYITAHOME 300 Gallon Double-Wall Deck Box
Best build on paper — and sold by Amazon300 gal (listing)291 gal (60.6 × 33.5 × 33.1 in)Double-wall resin (listing)Gas struts, soft-close, lockable (lock not included)Not published — 'can be requested from customer service'Check price →
MIRADOR 281 Gallon Aluminum Deck Box (Horizon) product photoMIRADOR 281 Gallon Aluminum Deck Box (Horizon)
The metal one, from a maker that exists281 gal (listing and maker)340 gal (71.7 × 35.2 × 31.1 in)Aluminum and steel, powder-coated (listing)Soft-close pistons, lockableResidential-use warranty per miradoroutdoor.com; registration adds one year; the base term for deck boxes is on a sub-page we could not openCheck price →
TARKARI 370 Gallon Deck Box product photoTARKARI 370 Gallon Deck Box
SKIP370 gal (listing)318 gal (67.72 × 32.2 × 33.66 in) — the label exceeds the boxResin (listing)Hydraulic, lockable (lock not included)Not publishedCheck price →

Prices move constantly — any Amazon price shown is as of the date noted and subject to change; tap through for today's number.

Two shells, nine labels

Every resin box in the 300-plus class carries an “Item Dimensions” line in its Amazon detail table. We read them side by side. Then we multiplied.

Listing (as titled)Listed dimensions (in)Exterior volumeLabel ÷ exteriorSeller of record
TARKARI “370 Gallon”67.72 × 32.2 × 33.66318 gal116%ARTS BOX US
Decksplore “350 Gallon”67.72 × 32.2 × 33.66318 gal110%KKNEW US
KAMABOKO “330 Gallon”67.72 × 32.2 × 33.66318 gal104%KAMABOKO-US
Yardgrace “320 Gallon [Upgraded 3.0]“67.72 × 32.2 × 33.66318 gal101%ARTS BOX US
EFU “380 Gal Gen 2”57.87 × 32.24 × 33.66272 gal140%EFU1
Yardgrace “300 Gallon”57.87 × 32.24 × 33.66272 gal110% (its own table says 270)ARTS BOX US
ATMELT “300 Gallon” (part 248A)58.87 × 33.24 × 34.66294 gal102%ATMLT
KFY “320 Gallon”58.44 × 32.56 × 33.99280 gal114%Storage Oasis
YITAHOME “300 Gallon”60.6 × 33.5 × 33.1291 gal103%Amazon.com
NUNU LAB “320 Gallon”75.08 × 34.37 × ~33.7376 gal85%Amzaon’
MIRADOR “281 Gallon”71.7 × 35.2 × 31.1340 gal83%SORARA USA

Exterior volume is the most a box could hold if it had no walls and no lid. A real interior is smaller. So a label at 100% or more of the exterior is not an estimate; it is a number that cannot be true. Seven of the eleven are over. The two that are under — NUNU LAB and MIRADOR — are the two we rank first and fourth, and the third-party research we commissioned before reading the listings found the first shell sold under two more badges, LAUSAINT HOME on Amazon and ACOINEL at Target, at the same hundredth of an inch.

The seller column is the tell for who is who. ARTS BOX US sells the first shell as TARKARI 370 and as Yardgrace 320, and the second shell as Yardgrace 300. ATMELT and EFU print the same manufacturer part number, 248A, on boxes labelled 300 and 380. None of the resin brands on this table has a website: nunulab.com, atmelt.com and tarkari.com all redirect to a parked lander, kamaboko.com is a Japanese fish-cake company, and the one that does exist — yardgrace.com — is the same operation as TARKARI by seller. YITAHOME’s site answered 503 all day. Mirador’s store is real, sells the 281 direct for less than Amazon does, and lists a 370-gallon Urban above it that is not on Amazon at all.

The three failures, and they are the same as the 150-gallon class

Our large-deck-box page found that a resin box fails three ways — a lid that lets water in when opened, hinges that snap, and a shell that warps. The 300-plus tails add nothing new; they add scale. A 68-inch snap-together panel bows more than a 60-inch one. Owners of four of the five boxes here describe walls that bulge under cushions alone, bottoms that pull away from the sides when the box is pushed, and pieces that “do not clearly and positively snap together as instructions state”. Two describe wind: the TARKARI “blew apart in a wind storm”; the NUNU LAB’s lid “blew open and the plastic snapped all the hinges”. The MIRADOR, being metal, fails differently — bent panels out of the box and screw holes that will not line up.

Read those with the base composition in mind. Every rating on this page pools a size ladder: the NUNU LAB’s 1,182 ratings span boxes from 30 gallons up, and reviews of 33- and 35-gallon units sit on the 320’s own critical page. The star average is the family’s, not the big box’s.

Best overall: NUNU LAB 320 Gallon Deck Box

Winner
Our top pick

NUNU LAB 320 Gallon Deck Box

Best overall (the only shell bigger than its label) · The largest box of the class, 75 inches long, and the only one whose gallon figure fits inside its own dimensions, on the deepest base of the class (4.3★/1,182, pooled across 29 sizes and colours). The seller of record is a Ningbo storefront named 'Amzaon''. Owners describe walls that bow when loaded and a lid a windstorm opens.

Sold in 29 sizes and colours on this listing (30–320 gal) — this card is the 320 gal, Rattan Black. Check the size before you add to cart.

Your pick if you want the biggest box in the class and you have checked who is selling it: 75 by 34 inches of resin, a 4.3★/1,182 base, and the one 300-gallon-plus claim on Amazon that fits inside the box's own exterior volume (376 gallons). Not for you if a lid that can blow open in wind is a deal-breaker — that is its tail.

4.3 · 1,182 owner ratingsacross Amazon · September 2026 · listing-wide base
Check price at Amazon →

Picked before we checked what this link pays us.

NUNU LAB 320 Gallon Deck Box

Best overall (the only shell bigger than its label)

Sold in 29 sizes and colours on this listing (30–320 gal) — this card is the 320 gal, Rattan Black. Check the size before you add to cart.

Your pick if you want the biggest box in the class and you have checked who is selling it: 75 by 34 inches of resin, a 4.3★/1,182 base, and the one 300-gallon-plus claim on Amazon that fits inside the box's own exterior volume (376 gallons). Not for you if a lid that can blow open in wind is a deal-breaker — that is its tail.

4.3 · 1,182 owner ratingsAmazon · September 2026 · listing-wide base
Pros
  • The only 300-gallon-plus box on Amazon whose claimed capacity fits inside its exterior volume — 75 inches long against the 58–68 inch shells sold as '320' to '380'
  • The deepest owner base in the class, 4.3★ across 1,182
  • Sold in 29 sizes and colours from one listing, so the 320 can be matched to smaller boxes of the same look
Cons
  • Sold by a storefront named 'Amzaon'' — a Ningbo e-commerce company trading under a misspelling of Amazon's name; the brand has no website (nunulab.com parks to a lander) and publishes no warranty
  • 'Wind blew it open and the plastic snapped all the hinges, pretty cheap brittle plastic' — the seller replaced it; another owner: 'the cover can blow open with strong winds. The piston isn't real strong'
  • 'The walls bow out and cause the bottom to come apart' when loaded with cushions; assembly parts 'not all marked', 'wouldn't click' — 122 critical reviews (10% of the base)
  • The rating pools 29 variants from a 30-gallon box up; reviews of 33- and 35-gallon units sit on this page
What owners complain aboutDefect reports

The shell is not rigid and the lid is not wind-safe. 'The walls bow out and cause the bottom to come apart'; 'really flimsy at the bottom where the walls are attached'; 'Wind blew it open and the plastic snapped all the hinges'; 'the cover can blow open with strong winds. The piston isn't real strong to hold it shut'. Assembly: 'the parts are not all marked', 'wouldn't click', 'took me 45 minutes'.

10 critical read 2026-09-17 of 122 critical on a 1,182-rating base (10%); flimsy/bowing structure in 4, wind and lid in 2, assembly in 4; dates Sep 2025 → Sep 2026; 10/10 Verified Purchase, 0 Vine; variant lines on the page include 33- and 35-gallon units. · critical reviews read September 2026

Check price at Amazon →
✓ Safety: no active recallCPSC recall API checked 2026-09-16: ProductName=deck box → 0 records, ProductName=NUNU LAB → 0 records, with the positive control ProductName=heater returning 181 records in the same sitting. CPSC's long-standing guidance on storage chests concerns freely falling lids that can trap a child; this box has a lockable lid and a lid that holds itself open. Lock it when small children play nearby, and never let a child climb in.

Why it wins. It is the longest shell in the class by a foot, and the only one whose gallon figure is smaller than its exterior volume. Its base is the deepest here, and the visible cards are all Verified Purchase with no Vine reviews. Set beside boxes that print 370 on a 318-gallon shell, an honest 320 on a 376-gallon exterior is a low bar that only one product clears.

Not for you if: you cannot accept the seller. The offer is sold by “Amzaon’” — a third-party storefront whose seller page names Ningbo Pansen E-commerce Co., trading under a misspelling of the platform’s own name. It ships from the same warehouse and carries the same 30-day return as the others, but it is not Amazon, and the brand behind it has no website. The other catch is in the tail: two owners describe wind lifting the lid, one with every hinge snapped. Site it out of the wind, and lock it.

Best value: ATMELT 300 Gallon Deck Box with Support Rod

ATMELT 300 Gallon Deck Box with Support Rod

Best value (the class's best-seller)

Sold in 33 sizes on this listing (42–380 gal) — this card is the 300 gal, Black. Check the size before you add to cart.

Your pick if you want the box the most people are buying right now for the least money: the class's best-selling 300, 4.8★/64 so far, a support rod for the lid, and a shell (294 gallons exterior) that is nearly as big as its label. Not for you if you want proof of longevity — the base is under 100 and the two critical reviews are from the last month.

4.8 · 64 owner ratingsAmazon · September 2026 · early data · listing-wide base
Pros
  • The cheapest 300-gallon box on this page and the best-selling one on Amazon the day we read it (#1,667 in all of Patio, Lawn & Garden)
  • A claimed capacity within 2% of the shell's exterior volume — the honest end of a class where labels run 20–40% past the box
  • No one-star or two-star reviews yet on the visible histogram (89% five-star)
Cons
  • An early base: 64 ratings, most of them from the last two months — the class's failures (bowing walls, lids in wind) show up in year one and this box has not had one
  • 'Water still gets in it… everything in there is soaked' — one of only two critical reviews; the other calls it 'pretty junky quality considering the cost' and 'certainly not a one person job'
  • The same shell, part 248A, is sold by EFU as a '380 gallon' box: the number on the front is a marketing choice
  • No brand site (atmelt.com parks to a lander) and no warranty term; the rating pools 33 sizes from 42 gallons up
What owners complain aboutDefect reports

Water inside, and a hard two-person assembly. 'Water still gets in it. Can't really tell from the picture but everything in there is soaked'; '(360 gallon product review:) The directions are horrible. Installation was not easy, & it's certainly not a one person job. It's also pretty junky quality considering the cost… however, once assembled, it's fine'.

2 critical read 2026-09-17 of a 64-rating base (3%); water ingress in 1, assembly/quality in 1; dates Aug 24 and Aug 31, 2026; 2/2 Verified Purchase, 0 Vine; one card is from the 360-gallon variant. · critical reviews read September 2026

Check price at Amazon →
✓ Safety: no active recallCPSC recall API checked 2026-09-16: ProductName=deck box → 0 records, ProductName=ATMELT → 0 records, with the positive control ProductName=heater returning 181 records in the same sitting. CPSC's long-standing guidance on storage chests concerns freely falling lids that can trap a child; this box has a lockable lid and a lid that holds itself open. Lock it when small children play nearby, and never let a child climb in.

Currently unavailable (re-read 2026-09-27). The listing now reads “Currently unavailable. We don’t know when or if this item will be back in stock”, no seller offers it, and its rating base has fallen from 64 to three, the pattern of a listing being purged or re-listed. We are holding the slot rather than crowning a box we have not read; what follows is the September 17 read.

The cheapest box on the page and, on the day we read it, the highest-ranked of the five on Amazon’s best-seller list — #1,667 across all of Patio, Lawn & Garden. Its shell measures 294 gallons of exterior against a 300 label, the closest to honest of any resin box here. The base is early: 64 ratings, most from the last two months, and no one- or two-star reviews yet on the histogram. The two critical reviews are the class’s two failures in miniature: one owner’s contents “soaked”, one owner’s “certainly not a one person job”. The part number, 248A, is the one EFU prints on a box labelled 380 gallons, which tells you what the number on the front is worth.

Double-wall, sold by Amazon: YITAHOME 300 Gallon Double-Wall Deck Box

YITAHOME 300 Gallon Double-Wall Deck Box

Best build on paper — and sold by Amazon

Sold in 10 sizes on this listing (35–300 gal) — this card is the 300 gal, Black. Check the size before you add to cart.

Your pick if you want the one 300-gallon box with a maker behind it and Amazon as the seller: double-wall resin, gas struts, a returns counter you have used before. Not for you if the histogram matters more than the spec sheet — 17% of its 422 owners gave it one or two stars, and the tail is broken parts in the box and a lid that warped inside a year.

4.1 · 422 owner ratingsAmazon · September 2026 · listing-wide base
Pros
  • Double-wall panels and gas struts — the two build features the rest of the class claims and this listing states
  • Sold by Amazon.com, not a marketplace storefront: Amazon's own returns desk stands behind it
  • The only brand in the 300-gallon class with a website of its own (yitahome.com — it answered 503 the day we checked)
Cons
  • 'Half of the pieces were broken or cracked' on arrival; 'corner piece was chipped off'; 'mine lasted about a year… ended up warping. Especially at the top so now it does not seal' — 47 critical reviews on a base whose histogram is 8% two-star and 9% one-star, the worst on this page
  • 'This box relies on interlocking resin parts to hold it together, and when they're poorly made or misaligned, the whole box feels flimsy and unstable'; 'VERY cheap thin. Pop together design'
  • Instructions with 'no words, and very inadequate pictures'
  • The rating pools 10 sizes from 35 gallons up; 35- and 260-gallon reviews sit on this page
What owners complain aboutDefect reports

Arrives broken, assembles loose, warps within a year. 'Half of the pieces were broken or cracked'; 'came damaged in box from vendor, corner piece was chipped off'; 'Material is real flimsy and easy to bend'; 'relies on interlocking resin parts… the whole box feels flimsy and unstable'; 'Barely any support to put anything inside.. flimsy bottom'; 'Good size but mine lasted about a year. I kept it out of the sun and still ended up warping. Especially at the top so now it does not seal'.

8 critical read 2026-09-17 of 47 critical on a 422-rating base (11%; histogram 8% two-star, 9% one-star); damaged on arrival in 2, flimsy structure in 4, warping in 1, instructions in 1; dates Jun 2025 → Apr 2026; 8/8 Verified Purchase, 0 Vine; variant lines include 35- and 260-gallon units. · critical reviews read September 2026

Check price at Amazon →
✓ Safety: no active recallCPSC recall API checked 2026-09-16: ProductName=deck box → 0 records, ProductName=YITAHOME → 0 records, with the positive control ProductName=heater returning 181 records in the same sitting. CPSC's long-standing guidance on storage chests concerns freely falling lids that can trap a child; this box has a lockable lid and a lid that holds itself open. Lock it when small children play nearby, and never let a child climb in.

On the spec sheet this is the box to buy: double-wall panels, gas struts, a brand with a website, and Amazon.com — not a storefront — as the seller. The owners disagree with the spec sheet. Its histogram is the worst on the page, 8% two-star and 9% one-star, and the critical reviews are about the plastic, not the design: “half of the pieces were broken or cracked” on arrival, “very cheap thin”, and a box that “lasted about a year… ended up warping, especially at the top so now it does not seal”. We carded it because the seller and the construction claim are genuinely different from the rest, and because a reader who values Amazon’s own returns desk should have that option in front of them with its numbers attached.

The metal one: MIRADOR 281 Gallon Aluminum Deck Box

MIRADOR 281 Gallon Aluminum Deck Box (Horizon)

The metal one, from a maker that exists

Sold in 8 sizes and colours on this listing (134–281 gal) — this card is the 281 gal, Latte. Check the size before you add to cart.

Your pick if you would rather pay three times the class price for a box with a manufacturer, a warranty page and wheels: rust-proof aluminum and steel, a soft-close lid, 281 gallons, 4.0★/88. Not for you if you want it built in an afternoon — the tail is bent panels, screw holes that do not line up and a lid hatch owners ruined on the first try.

4.0 · 88 owner ratingsAmazon · September 2026 · early data · listing-wide base
Pros
  • A manufacturer, a direct store and a warranty page — the only one of the five with any of the three
  • Metal, not snap-together resin: no bowing walls, no bottom pulling away from the sides in the tail
  • Wheels on a 120 lb box, and a claimed capacity that sits well inside the shell's 340-gallon exterior
Cons
  • 'The sides come bent which makes them difficult to put together (this was not a packaging problem. I bought two and each had both long side panels bent)'; 'the screw holes do not line up'; 'thousands of screws… I still messed up the lid hatch. Once you get it together, they make it impossible to go back' — 17 critical reviews and a 13% one-star share
  • 'Both of the lift pistons for the lid' failed on one owner's box; rivet nuts strip if the driver is off vertical
  • At $599 it is nearly three times the class price, and 281 gallons is under the 300 mark the rest of this page is sold on; the maker's 370-gallon Urban is $899 direct and not on Amazon
  • The rating pools four sizes and two colours; 134- and 175-gallon reviews sit on this page
What owners complain aboutDefect reports

Assembly of a bent metal kit. 'The sides come bent… I bought two and each had both long side panels bent'; 'the screw holes do not line up. Had to leave several screws off'; 'thousands of screws… I still messed up the lid hatch. Once you get it together, they make it impossible to go back'; 'Hold power driver in precisely vertical position… the thread damages so easily… the bolt came out with the rivet nuts'; 'both of the lift pistons for the lid' failed; 'most difficult thing to build I've ever bought from Amazon'.

8 critical read 2026-09-17 of 17 critical on an 88-rating base (19%; histogram 13% one-star); assembly/bent panels/misaligned holes in 6, pistons in 1, delivery in 1; dates Jul 2025 → Apr 2026; 8/8 Verified Purchase, 0 Vine; variant lines include 134- and 175-gallon units. · critical reviews read September 2026

Check price at Amazon →
✓ Safety: no active recallCPSC recall API checked 2026-09-16: ProductName=deck box → 0 records, ProductName=MIRADOR → 0 records, with the positive control ProductName=heater returning 181 records in the same sitting. CPSC's long-standing guidance on storage chests concerns freely falling lids that can trap a child; this box has a lockable lid and a lid that holds itself open. Lock it when small children play nearby, and never let a child climb in.

The only box here from a company: Mirador Outdoor, a Sorara line with a direct store, a dealer program and a warranty page that says “residential use only” and offers an extra year on registration. Aluminum and steel, wheels, a soft-close lid, 120 pounds. It is under the 300 mark and nearly three times the class price, and the maker’s own store sells it for less than Amazon does. Its tail is not the resin tail; it is a metal kit’s tail — “the sides come bent”, “the screw holes do not line up”, “thousands of screws”. If you want bigger from the same maker, the 370-gallon Urban exists, direct-only, at a price above anything on this page — the largest deck box we found from a manufacturer with a name.

SKIP: TARKARI 370 Gallon Deck Box

TARKARI 370 Gallon Deck Box

SKIP

Sold in 14 sizes and colours on this listing (14 variants (sizes and colours; gallon figures not printed in the twister)) — this card is the 370 gal, Black. Check the size before you add to cart.

Your pick if you have decided that the number on the front of a box is measured by someone. TARKARI's '370 gallons' is printed on a shell that is 67.72 by 32.2 by 33.66 inches — 318 gallons of exterior — and that the same seller lists as 320 gallons under the Yardgrace name. 4.3★/211, pooled, and a tail that includes 'it blew apart in a wind storm'.

4.3 · 211 owner ratingsAmazon · September 2026 · listing-wide base
Pros
  • Looks like the others — because it is: the same shell four brands sell
  • 'Love the size and look' — the first half of a two-star review
Cons
  • The claimed 370 gallons is larger than the box's own exterior volume (318 gallons from the listing's dimensions); the same seller, ARTS BOX US, sells the same 67.72 × 32.2 × 33.66 in shell as '320 gallons' under the Yardgrace name
  • 'It blew apart in a wind storm. This is a plastic snap together plastic box. If you buy it reinforce the box with wood braces on all corners'
  • 'If you put any weight in the bottom of it, the bottom of it sags, and it pulls away from the sides'; 'has already started to bow in the front' after two weeks; 'the sides are bulging' with cushions alone — 31 critical reviews, 15% one- and two-star
  • No brand site (tarkari.com parks to a lander), no warranty; the listed weight (30.9 lb) is less than half what the same shell weighs on its sibling listings
What owners complain aboutDefect reports

A snap-together shell that will not stay together. 'It blew apart in a wind storm… reinforce the box with wood braces on all corners'; 'if you put any weight in the bottom of it, the bottom of it sags, and it pulls away from the sides'; 'has already started to bow in the front' after two weeks; 'the sides are bulging' holding cushions alone; 'Bottom and sides kept falling apart' during assembly; 'The bottom just sort of lines up some tabs and slots but nothing clicks in'.

8 critical read 2026-09-17 of 31 critical on a 211-rating base (15%; histogram 7% two-star, 8% one-star); structural bowing/sagging in 5, wind in 1, assembly in 2; dates Jul 2026 → Sep 2026; 8/8 Verified Purchase, 0 Vine; the variant line on the page reads 200 gallons. · critical reviews read September 2026

Check price at Amazon →
✓ Safety: no active recallCPSC recall API checked 2026-09-16: ProductName=deck box → 0 records, ProductName=TARKARI → 0 records, with the positive control ProductName=heater returning 181 records in the same sitting. CPSC's long-standing guidance on storage chests concerns freely falling lids that can trap a child; this box has a lockable lid and a lid that holds itself open. Lock it when small children play nearby, and never let a child climb in.

The number on this box is larger than the box. Its listing gives 67.72 × 32.2 × 33.66 inches — 318 gallons if the walls were infinitely thin — and calls it 370. Its seller of record, ARTS BOX US, sells the identical dimensions as “320 Gallon” under the Yardgrace name, and the detail table lists a weight less than half of what the same shell weighs on the sibling listings. The owners’ reports are the class’s, louder: a bottom that “sags, and it pulls away from the sides”, a front that “has already started to bow” in two weeks, and one that “blew apart in a wind storm” with the advice to “reinforce the box with wood braces on all corners”. That is a SKIP on the label alone; the tail makes it an easy one.

The boxes we read and did not card

KAMABOKO 330 (4.3★/570, pooled across 48 variants from 35 gallons): the first shell, sold by KAMABOKO-US; its tail is a lid cracked in the first week and an owner who measured a “150” at 102 gallons. Decksplore 350 (4.4★/149): the first shell under a Portland-based brand with a real website and a “32-climate testing protocol” on its about page — the one badge here with a company behind it, which is why we would read it first at the next audit; its warranty page carries no term. Yardgrace 320 [Upgraded 3.0] (4.2★/127) and Yardgrace 300 (4.6★/83): the same seller as the TARKARI, on both shells; the 300’s own detail table says 270. EFU 380 Gen 2 (4.6★/58): the second shell, part 248A, at 140% of its exterior, three critical reviews in a month including “falls apart very quickly”. KFY 320 (4.4★/198): the second shell’s cousin at 114%, pooled across 35 variants from 30 gallons.

We also re-read the credentialed tests. Bob Vila’s month-long trial (page dated 9 August 2026) tops out at the Keter Java 230; The Spruce’s and BHG’s hands-on lists stop there too. None of the three hands-on tests we read puts hands on a 300-gallon box. That is not a gap in our reading; it is the state of the category.

How to pick a 300-gallon deck box

  • Divide before you buy. Length × width × height in inches, ÷ 231. If the label is bigger than the answer, the label is fiction. Every listing prints its dimensions; not one prints the arithmetic.
  • Read the seller line, not just the brand. Three brands, one seller is common here. “Sold by Amazon.com” is the exception (YITAHOME), and it is worth something at return time.
  • Wind is the enemy of a 68-inch lid. Two of five tails describe a lid blown open. Site the box against a wall, and use the padlock hole for a lock even if theft is not the worry — it keeps the lid down.
  • Bag what you store. No resin box on this page seals; the owners of all five say so. Cushions in bags, chemicals not at all — see our pool-storage page for where chemicals belong.
  • If 230 gallons will do, buy the 230. The Keter Luma 230 on our large-deck-box page comes from a company with a warranty document and a decade of owner history. This class exists because people search for it.

FAQ

What is the biggest deck box you can buy?

On Amazon, the NUNU LAB 320: 75 inches long, 34 wide, and the only box sold as 300 gallons or more whose claimed capacity fits inside its own exterior volume (about 376 gallons by its dimensions). Every other '300', '320', '350' and '380' we read is printed on a shell that is 58 to 68 inches long and holds 272 to 318 gallons of exterior volume. The biggest box with a manufacturer behind it is Mirador's Urban at 370 gallons, sold only from the maker's own store at a price above anything on this page; on Amazon the biggest name-brand box is still the Keter Luma 230 from our large-deck-box page.

Is a 320-gallon deck box really 320 gallons?

Usually not. A gallon is 231 cubic inches, so a box's length × width × height ÷ 231 is the most it could ever hold — and that is the outside of the shell, before walls and a lid. The most common 300-plus shell measures 67.72 × 32.2 × 33.66 inches on its own listings, which is 318 gallons of exterior volume; it is sold as 320, 330, 350 and 370 gallons by four different brands. A second shell at about 58 × 32 × 34 inches (272 gallons exterior) is sold as 300, 320 and 380. Read the dimensions, do the division, and treat the gallon figure as a brand name.

Which 300-gallon deck box is best?

The NUNU LAB 320 for most people: the deepest owner base in the class (4.3★ across 1,182), the longest shell, and an honest capacity claim. Its catches are real: the seller of record is a Ningbo storefront named 'Amzaon'', and its critical reviews describe a lid a windstorm can open. If you want the box the most people are buying for the least money, the ATMELT 300; if you want Amazon itself as the seller and double-wall panels, the YITAHOME 300 — with the worst histogram on the page.

Are these deck boxes waterproof?

The listings say waterproof; the owners say otherwise, on every box here. 'Water still gets in it… everything in there is soaked' (ATMELT), 'the connections could also be a bit more water tight' (TARKARI), 'warping, especially at the top so now it does not seal' (YITAHOME). These are snap-together resin panels, and the seam is the weak point. Bag the cushions, tilt the lid to drain before you open it after rain, and expect 'weather-resistant' to be the true word.

Why does the same box have different gallon numbers on different listings?

Because the brands are badges, not makers. TARKARI's 370 and Yardgrace's 320 are the same 67.72 × 32.2 × 33.66 inch shell with the same seller of record, ARTS BOX US. ATMELT's 300 and EFU's 380 share the manufacturer part number 248A. KAMABOKO's 330 and Decksplore's 350 match the first shell to the hundredth of an inch. None of the resin brands here has a website that resolves to a company; the number on the front is a marketing decision made per listing.

Should I just buy a Keter or Suncast instead?

If you can live with 230 gallons, yes — that is the honest answer this page owes you. Keter's Luma 230 and Suncast's 200 come from companies with warranty documents, a decade of owner history and a returns desk, and the three hands-on tests we read (Bob Vila, The Spruce, BHG) all stop at 230 gallons. The 300-plus class exists because people search for it, not because a manufacturer built for it. Buy here for the size, knowing what you are buying.

The ladder

Every Deck Boxes & Bins showdown, by division

Same fight, different budgets. The head rulings first, then each weight class as the price climbs.

  1. CatchweightThe Best Deck Box Side Tables of 2026: The 30-Gallon Box That Holds 30, the One a Tester Took Through Iowa Storms, and the "37-Gallon" Drum That Holds 29
  2. CatchweightThe Best Large Deck Boxes of 2026 (130 to 230 Gallons): The One 14,000 Owners Bought, the One Built Like a Cooler, and the One to Skip

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