Packing cubes vs compression bags: what actually saves space

Trahvl editorial deskUpdated September 2026Airline dimensions re-read from the airlines own pages on 14 September 2026
Short answer

Compression saves volume, because it pushes out the air between clothes. Packing cubes save almost no volume at all; what they save is the space a loose load wastes, and the time you spend hunting through it. For a shallow sizer such as Ryanair 55 x 40 x 20 cm, compression decides whether the bag closes. For a duffel you open every day, cubes decide whether you can find anything.

The comparison gets argued on the wrong axis. The question is not which one is better, it is which problem you have: too much air, or too much sprawl. Those are different problems with different fixes, and a shallow sizer punishes only one of them.

On this page
  1. What each one removes
  2. The depth limit decides it
  3. The litre test
  4. Using both
  5. Three trips worked through
  6. When compression is wrong
  7. Questions people ask

What each one removes

A packing cube is a container with fixed sides. It does not compress anything. What it does is stop clothes from spreading into every corner of the bag as you move, which is why a loosely packed bag feels full at the top and hollow at the bottom. A compression bag does the opposite job: it leaves the load shape alone and squeezes the air out of it.

Packing cubes Roll-up compression bags Vacuum bags and pumps
Removes air No Yes, by hand pressure Yes, most of it
Keeps the bag organised Yes, this is the whole point Partly, if you label them No, one solid brick
Creases clothes Less than loose packing Some Most, and worst on collars
Works on the return leg Yes Yes, until the zip wears Needs the pump again; seals often fail on the way back
Extra weight 60 to 120 g per cube 80 to 150 g per bag 200 g or more with the pump
Best for Soft duffels, backpacking, anything opened daily Knitwear, t-shirts, fleece, bulky soft items Home storage and one-way moves
Where the volume actually comes fromCompression does not shrink fabric. It removes the air your clothes were holding. Bulk knitwear and fleece hold a lot of that air, which is why they compress well. Shoes, a toiletry bag, a laptop and a structured jacket are already at their minimum volume, so no bag will make them smaller. Any compression percentage you read online has to state what the starting pack was, and almost none of them do, which is why they cannot be compared.

The depth limit is the number that decides it

Airlines do not publish a volume. They publish three dimensions, and the smallest of the three is usually the one that fails. The box in the sizer and the usable space inside your bag are different numbers, but the box tells you what you are up against.

Volumes are the outer box the sizer accepts, calculated from the published dimensions. Usable packing space inside a bag is less than this, because of wheels, handles, fabric thickness and the shape of the opening.

Sizer box Outer box volume Who uses it
40 x 30 x 20 cm 24.0 L The free Wizz Air under-seat bag
45 x 36 x 20 cm 32.4 L The free easyJet small cabin bag
55 x 40 x 20 cm 44.0 L Ryanair cabin bag with Priority
22 x 14 x 9 in (55.9 x 35.6 x 22.9 cm) 45.4 L American Airlines, Delta, JetBlue, Alaska Airlines, United
55 x 38 x 22 cm 46.0 L Emirates
56 x 36 x 23 cm 46.4 L Qantas domestic overhead bag, Cathay Pacific
55 x 35 x 25 cm 48.1 L KLM and Air France
55 x 40 x 23 cm 50.6 L Lufthansa, Air Canada, Turkish Airlines, Norwegian
56 x 45 x 25 cm 63.0 L British Airways cabin bag, easyJet large cabin bag

The Ryanair box is 44 litres. The British Airways box is 63 litres. Both are called a cabin bag. That 19 litre gap is larger than the free Wizz Air bag, so a bag bought for one airline can be turned away by another even though it fits its own sizer comfortably. This is the reason to buy a bag that measures at or under 55 x 40 x 20 cm: it fits every European low-cost sizer, and it is inside every North American limit as well.

Why compression helps here and cubes can hurtA compression bag makes a soft load flatter, which is exactly what a 20 cm depth limit rewards. A packing cube does the opposite: it holds its own shape, and a full cube is a rigid 8 to 10 cm block that will not squash when the gate agent pushes the bag into the sizer. If you are flying a carrier with a 20 cm depth limit, compress the bulky soft items and use at most one small cube for cables and small items.

The litre test you can run at home

You do not need a laboratory. You need a tape measure and one repeatable way of packing the same pile of clothes.

  1. Lay out the clothes for one trip and photograph the pile. This is your control.
  2. Pack it loose and measure the height the load reaches, tape measure against the inside wall. Note it.
  3. Repack the same clothes with compression bags and measure again. The change in height, multiplied by the width and depth, is the volume you saved in litres.
  4. Repack with packing cubes and measure a third time. Most people find the cube load is taller, because cubes do not deform around the bag.

The step people skip is the fourth one, which is why cube marketing survives. Cubes do not make a load smaller. They make it findable. Whether that trade is worth 2 to 4 litres depends on whether you are flying a 63 litre sizer or a 44 litre one.

How to use both without repacking your whole bag

  1. Compress the soft bulk only. Knitwear, t-shirts, fleece and a puffer jacket go into compression bags. Everything else stays out.
  2. Use one or two cubes, not six. One for cables and adapters, one for underwear and socks. Compression bags go at the bottom where the frame fixes the depth; cubes go near the opening where you need access.
  3. Weigh the packed bag before you leave. Compression makes a bag look smaller and feel heavier per litre, and a 44 litre bag of compressed knitwear can pass an 8 kg limit or blow straight through it.

Three trips worked through

Trip What to compress What to cube What to leave at home
5 days, city, carry-on only, late spring Five t-shirts and one light knit One small cube for underwear, socks, cables A second pair of shoes, a hairdryer, more than two bottoms
12 days, cold, checked bag Two fleeces and a puffer jacket One cube per person for small items Anything you plan to buy there
4 days, low-cost carrier, 20 cm depth limit Everything soft, in roll-up bags One flat pouch only, no rigid cube Hard-sided toiletry cases, spare shoes, a laptop bag that does not flatten

When compression is the wrong tool

Worth it if

  • You are flying a carrier with a shallow sizer and a soft bag
  • You are packing knitwear, fleece or down
  • You are moving house or storing winter clothes
  • You want the same bag to work on both legs of the trip without a pump

Skip it if

  • You are packing a suit, a blazer or anything with a stiff collar
  • You need to open the bag several times a day
  • You are carrying items that need to stay dry and sealed
  • You are over a weight limit rather than over a volume limit

Related guides

Questions people ask

Are compression packing cubes really better than regular packing cubes?
For volume, yes, but only by the amount of air you push out of the clothes inside them. A compression cube takes the same footprint as a regular cube and turns a looser load into a flatter one. With cotton t-shirts and knitwear the difference is noticeable. With structured jackets, shoes or a suit it is almost nothing, because those items are already at their minimum volume.
Are compression cubes a better choice for packing than vacuum bags?
Vacuum bags remove more air and stay compressed while the seal holds. They also need a pump, they are awkward to reseal on the way home, and the clothes come out creased. Compression cubes win on the return trip and on trips with more than one stop. Use vacuum bags for storage at home, not for a fortnight of city hopping.
Does TSA hate packing cubes?
No. There is no TSA rule about packing cubes, and the liquids rule is about containers, not about how clothes are organised. The practical effect is on the X-ray image: several dense cubes can look like a solid block on the screen, and if your bag is opened by hand the officer works through the layers. Cubes do not cause the search. They make one slower if it happens.
Does TSA allow compression bags?
Yes. Nothing in the TSA carry-on rules prohibits compression bags, and the 3-1-1 liquids rule applies to the bottles inside them, not the bag itself. If your bag needs a handheld pump, that pump travels as an ordinary item. On what survives the compression: nothing is legally forbidden, but blazers, shirts and anything with a stiff collar come out creased and stay that way, so we have not found a published study that puts a number on loft loss from a single trip, which is why this guide explains the mechanism instead.

Sources

  1. Ryanair. Ryanair bag policy, help centre — help.ryanair.com/hc/en-us/articles/12888036565521-Ryanair-s-Bag-Policy
  2. British Airways. Baggage essentials — www.britishairways.com/content/en/us/information/baggage-essentials
  3. easyJet. Cabin bags — www.easyjet.com/en/help/baggage/cabin-bags
  4. Wizz Air. Baggage allowance — wizzair.com/en-gb/help-centre/booking-information-and-services/baggage/baggage-allowance
  5. American Airlines. Carry-on bags and size limits — www.aa.com/i18n/travel-info/baggage/carry-on-baggage.jsp
  6. Transportation Security Administration. Liquids, aerosols and gels rule (3-1-1) — www.tsa.gov/travel/security-screening/liquids-aerosols-gels-rule

Bags that fit the numbers above

Packing cubes, compression pouches and carry-on bags listed with their actual measured dimensions.

See the range

Which one to buy

Every option this store stocks, with price, type and who it suits, is compared on one page.

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