Packing Cube Sizes Explained
Small, medium and large are not standard units. One brand's medium is 18 liters and another's whole three-piece set is 11 — here is what the letters actually mean.
We have not tested this gear. Every figure here is compiled from published manufacturer specifications and published airline policies, and the arithmetic is public so you can check it. This page contains affiliate links — see the affiliate disclosure.
There is no industry standard. Peak Design publishes a 18 L medium and a 9 L small; Eagle Creek’s entire three-piece XS/S/M set is 11 L combined. A “medium” cube can therefore be anything from about 5 L to 18 L depending on whose box it came in.
| Cube | Published capacity | Published footprint | Weight |
|---|---|---|---|
| Peak Design Packing Cube (Medium) | 18 L | 12.6 × 12.6 × 6.7 in | 0.32 lb |
| Eagle Creek Pack-It Reveal Set (XS/S/M) | 11 L total | Not published | 0.51 lb |
| Peak Design Packing Cube (Small) | 9 L | Not published | 0.25 lb |
| Veken Packing Cubes (6-piece) | Not published | 17.5 × 12.15 × 4 in | 0.65 lb |
| Gonex Compression Cubes (4-piece) | Not published | 17.3 × 13 × 3.54 in | 0.73 lb |
| # | Product | Published capacity | Fits | Score | Price |
|---|---|---|---|---|---|
| 1 | Peak Design Packing Cube (Medium)A single cube doing the whole job in a 40 L bag | 18 L | 11 of 11AA DL UA WN … | 9.4 | Check price on Amazon#ad How we earn |
| 2 | Peak Design Packing Cube (Small)Personal-item bags and 20 L daypacks | 9 L | Not published | 8.9 | Check price on Amazon#ad How we earn |
| 3 | Eagle Creek Pack-It Reveal Packing Cube Set (XS/S/M)Anyone who wants cubes once and never again | 11 L | Not published | 8.3 | Check price on Amazon#ad How we earn |
| 4 | Veken Packing Cubes (6-piece set)Two people sharing one case and needing their halves separate | Not published | 11 of 11AA DL UA WN … | 5.6 | Check price on Amazon#ad How we earn |
| 5 | Gonex Compression Packing Cubes (4-piece set)First-time cube buyers testing whether cubes suit them at all | Not published | 11 of 11AA DL UA WN … | 5.6 | Check price on Amazon#ad How we earn |
No live price is currently verified, so every button here reads Check price on Amazon rather than a number we cannot stand behind. See how we handle prices.
Why the letters are meaningless
Cube sizing is set by whoever designed the range, and nothing constrains it. Peak Design’s medium holds 18 L — more than the combined 11 L of Eagle Creek’s three-piece XS/S/M set. Both are honest products; they are simply not describing the same thing.
The consequence is practical rather than pedantic. If you buy a “medium cube” expecting it to hold roughly what your last medium cube held, you have no basis for that expectation. Buy liters, not letters.
What each size actually holds
Volume is only useful once you convert it into clothing. These are approximate and depend heavily on how you fold, but they give the letters something to mean:
| Volume | Roughly holds | Typical use |
|---|---|---|
| 3–5 L | Underwear and socks for a week, or one bulky sweater | The small cube in a set — the one people actually use most |
| 8–10 L | Three or four shirts, or two days of mixed clothing | A personal item, or one category in a carry-on |
| 15–18 L | Most of a week's clothing for one person | The whole job in a 40 L bag, in a single cube |
| 25 L and up | A week for two people, or bulky winter layers | Checked luggage — it will not fit usefully in a carry-on |
How many cubes fit a 40 L carry-on
Less than the arithmetic suggests, and this is where most people go wrong. A 40 L bag does not hold 40 L of cubes, for two reasons.
- Bag interiors are not rectangular. Tapered sides, a curved back panel and internal pockets all eat volume that a cube cannot use, because a packed cube is a rigid-ish block.
- Cubes have walls. Every seam and zip is volume that holds no clothing. Four cubes have four sets of walls; one cube has one.
A realistic figure is around 75% — so a 40 L pack takes roughly 30 L of cubes before things stop fitting. In practice that is one 18 L cube plus a 9 L cube with room left, or a three-piece set with room to spare.
Which is the strongest argument for fewer, larger cubes in a carry-on. Six small cubes in a 40 L bag is a lot of wall and a lot of subdivision you will not use. A week in a carry-on, laid out.
Footprint matters as much as volume
Two cubes of identical volume pack completely differently depending on their proportions. A long, flat cube at 17.5 × 12.15 × 4 in lies across the bottom of a suitcase and wastes almost nothing. A cube at 12.6 × 12.6 × 6.7 in is nearly square and stacks upright in a backpack.
This is why the flat sets tend to suit wheeled cases and the square ones suit packs: a rolling case is a shallow rectangle you fill in layers, while a travel backpack is a deeper box you fill in columns.
Two of the five sets here publish a footprint and no volume; two publish a volume and no footprint. Only the Peak Design medium publishes both, which is worth noticing when you are trying to plan a pack in advance.
Which sizes to actually buy
- Carry-on only, one person → one 15–18 L cube. It does the entire job, adds one set of walls rather than four, and weighs 0.32 lb.
- You want clothes separated by type → a three-piece set around 11 L total. Eagle Creek’s publishes a lifetime warranty at 0.51 lb for the set.
- Personal item or daypack → one 9 L cube, and nothing else. Depth is your constraint in a 17 × 10 × 9 in box, not volume.
- Two people sharing a case → a six-piece set, which is the one scenario where that much subdivision earns its walls.
- Do not buy → anything over 25 L for carry-on travel. It will not fit usefully in a 40 L bag once packed.
Every pick, with the working
Each entry below shows the published inputs, the four axis scores they produce, and what you give up. The order is the computed order, not a commercial one.
1 · A single cube doing the whole job in a 40 L bag
Peak Design Packing Cube (Medium)
18 L in one cube for 5.1 oz, with a divider that separates worn clothes from clean — the only cube here that solves the second half of a trip.
- Published size
- 12.6 × 12.6 × 6.7 in
- Weight
- 0.32 lb
- Capacity
- 18 L
- Weight per liter
- 0.02 lb/L
- Cost per covered year
- $2.00/yr
- Published list price
- $39.95
Warranty Peak Design lifetime guarantee
Fits 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY. See the limits.
What it does well
- 18 L in 5.1 oz is 0.018 lb per liter, the best carry efficiency in the packing category
- Halves in depth from 6.7 in to 3.1 in as it empties
- Dual compartments keep clean and dirty apart without a second bag
What you give up
- $39.95 for one cube against $59 for a three-cube Eagle Creek set
- 12.6 in square footprint wastes corners in a 14 in wide case
- Compression here reduces the cube, not the clothes inside it
The arithmetic behind the score
- Value 9.5/10 — $39.95 ÷ 20 yr = $2.00/yr; $39.95 ÷ 18 L = $2.22/L
- Airline-fit breadth 10.0/10 — Fits the published carry-on limit at 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY
- Carry efficiency 10.0/10 — 0.32 lb ÷ 18 L = 0.018 lb/L
- Warranty & support 8.0/10 — no stated end date (6 of 6); repair published (+2); airline damage not covered (+0)
Weights and breakpoints are published on how we rank. Where an input is not published, that axis is dropped and the remaining weights are re-normalized.
Specs: Peak Design published specifications and price, compiled 3 September 2026. Published compressed at 12.6 × 12.6 × 3.1 in and expanded at 12.6 × 12.6 × 6.7 in. The expanded figure is used here.
2 · Personal-item bags and 20 L daypacks
Peak Design Packing Cube (Small)
The medium cube's mechanism at half the volume — worth it only if 18 L is genuinely more cube than your bag can take.
- Published size
- Not published
- Weight
- 0.25 lb
- Capacity
- 9 L
- Weight per liter
- 0.03 lb/L
- Cost per covered year
- $1.50/yr
- Published list price
- $29.95
Warranty Peak Design lifetime guarantee
Fits No published dimensions to check.
What it does well
- Compresses from 9 L to 4.5 L, a true halving
- 3.99 oz added weight
- Same lifetime guarantee as the medium
What you give up
- $29.95 for 9 L against $39.95 for 18 L — the medium is better value per liter
- Small cubes encourage more cubes, and each one is added weight
- No mesh front, so you open it to see inside
The arithmetic behind the score
- Value 8.8/10 — $29.95 ÷ 20 yr = $1.50/yr; $29.95 ÷ 9 L = $3.33/L
- Airline-fit breadth not scored — No published dimensions to check against carrier limits.
- Carry efficiency 10.0/10 — 0.25 lb ÷ 9 L = 0.028 lb/L
- Warranty & support 8.0/10 — no stated end date (6 of 6); repair published (+2); airline damage not covered (+0)
Weights and breakpoints are published on how we rank. Where an input is not published, that axis is dropped and the remaining weights are re-normalized.
Specs: Peak Design published specifications and price, compiled 3 September 2026. Published at 32 × 17 × 8 cm compressed, 32 × 17 × 17 cm expanded.
3 · Anyone who wants cubes once and never again
Eagle Creek Pack-It Reveal Packing Cube Set (XS/S/M)
11 L of organization for 8.2 oz of added weight, under a warranty with no end date — the cleanest arithmetic in the packing category.
- Published size
- Not published
- Weight
- 0.51 lb
- Capacity
- 11 L
- Weight per liter
- 0.05 lb/L
- Cost per covered year
- $2.95/yr
- Published list price
- $59
Warranty Eagle Creek lifetime warranty
Fits No published dimensions to check.
What it does well
- Published weights of 45.4 g, 70.9 g and 113.4 g total 229.7 g — 8.1 oz for the set
- Lifetime warranty at $2.95 per covered year
- Mesh fronts mean you can see what is in a cube without opening it
What you give up
- $59 published is four to six times what an unbranded six-piece set lists at
- Organizing cubes, not compression cubes — they will not shrink anything
- 11 L across three cubes fills a fraction of a 40 L bag
The arithmetic behind the score
- Value 7.4/10 — $59 ÷ 20 yr = $2.95/yr; $59 ÷ 11 L = $5.36/L
- Airline-fit breadth not scored — No published dimensions to check against carrier limits.
- Carry efficiency 10.0/10 — 0.51 lb ÷ 11 L = 0.046 lb/L
- Warranty & support 8.0/10 — no stated end date (6 of 6); repair published (+2); airline damage not covered (+0)
Weights and breakpoints are published on how we rank. Where an input is not published, that axis is dropped and the remaining weights are re-normalized.
Specs: Eagle Creek published specifications and price, compiled 3 September 2026. Published per cube: XS 7.5 × 4.5 × 2.5 in, S 10 × 7 × 3 in, M 14 × 10 × 3 in.
4 · Two people sharing one case and needing their halves separate
Veken Packing Cubes (6-piece set)
Skip this one. Skip it if you are trying to plan a pack. Veken publishes footprint dimensions and no liter figure for any of the six pieces, which makes it the one set on this page you cannot size against a bag before it arrives. Six cubes in a 40 L pack is also more subdivision than most people ever use.
Six pieces at 10.4 oz including a laundry bag, which is the piece most sets leave out and every returning traveler needs.
- Published size
- 17.5 × 12.15 × 4 in
- Weight
- 0.65 lb
- Capacity
- Not published
- Weight per liter
- Not published
- Cost per covered year
- Not published
- Published list price
- Not published
Warranty No warranty term published
Fits 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY. See the limits.
What it does well
- 10.4 oz for six pieces, published
- Includes a 20 × 14 in laundry bag and a shoe bag
- Published 30 lb load capacity
What you give up
- Organizing cubes, not compression — nothing here reduces volume
- No published warranty term
- 4 in depth on every cube wastes the top of a 9 in deep case
The arithmetic behind the score
- Value not scored — No manufacturer-published price, so this axis is not scored.
- Airline-fit breadth 10.0/10 — Fits the published carry-on limit at 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY
- Carry efficiency not scored — No published capacity, so weight per liter cannot be computed.
- Warranty & support 0.0/10 — no published term (0 of 6); no published repair route (+0); airline damage not covered (+0)
Weights and breakpoints are published on how we rank. Where an input is not published, that axis is dropped and the remaining weights are re-normalized.
Specs: Veken published product specifications, compiled 3 September 2026. Published per cube: XL 17.5 × 12.15 × 4 in, L 13.75 × 12.75 × 4 in, M 13.75 × 9.75 × 4 in, S 11 × 6.75 × 4 in, plus a shoe bag and a laundry bag. Retail-only pricing. Check the live price before buying.
5 · First-time cube buyers testing whether cubes suit them at all
Gonex Compression Packing Cubes (4-piece set)
Real compression zips across four sizes at 11.7 oz for the set — the honest budget answer, with no warranty behind it.
- Published size
- 17.3 × 13 × 3.54 in
- Weight
- 0.73 lb
- Capacity
- Not published
- Weight per liter
- Not published
- Cost per covered year
- Not published
- Published list price
- Not published
Warranty No warranty term published
Fits 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY. See the limits.
What it does well
- Four graduated sizes with genuine compression zips
- 11.7 oz for the whole set, published
- Published 20 lb load rating per cube
What you give up
- No published warranty term of any kind
- Ripstop nylon at this tier abrades where a 300D polyester will not
- No published packed capacity, so cost per liter cannot be computed
The arithmetic behind the score
- Value not scored — No manufacturer-published price, so this axis is not scored.
- Airline-fit breadth 10.0/10 — Fits the published carry-on limit at 11 of 11 US carriers: AA, DL, UA, WN, AS, B6, F9, G4, HA, MX, SY
- Carry efficiency not scored — No published capacity, so weight per liter cannot be computed.
- Warranty & support 0.0/10 — no published term (0 of 6); no published repair route (+0); airline damage not covered (+0)
Weights and breakpoints are published on how we rank. Where an input is not published, that axis is dropped and the remaining weights are re-normalized.
Specs: Gonex published product specifications, compiled 3 September 2026. Published per cube: XL 17.3 × 13 × 3.54 in, L 14.5 × 10.6 × 3.54 in, M 11.8 × 8.9 × 3.54 in, S 9.8 × 7.5 × 3.54 in. Retail-only pricing. Check the live price before buying.
No live price is currently verified, so every button here reads Check price on Amazon rather than a number we cannot stand behind. See how we handle prices.