Do packing cubes save space? How compression cubes work

The case that closed easily on the way out and will not close on the last morning is a familiar problem. Packing cubes get sold as the fix, usually with the promise that they save space. Some do, some don't, and none of them does the thing many people hope for, which is make the bag lighter.

Two kinds of cube

A plain packing cube is a fabric box with a zip, often with a mesh panel so you can see what is inside. It holds clothes together. It does not make them smaller. Fill one loosely and it takes up about the same room as the clothes would on their own, plus a layer of fabric.

A compression cube has a second zip, the compression zip. Pack it, close the main zip, then close the compression zip, and the cube is pulled thinner. That presses air out from between the layers, so the clothes take up less room than they would loose in the case.

How much thinner depends on what is inside. Bulky, soft things like knitwear and fleece squash down the most. Stiff things like jeans and collared shirts squash down the least.

What no cube saves: weight

Compression changes the shape of your clothes, not their weight. A kilo of jumpers is still a kilo once it has been squeezed. Cubes add a little weight of their own, too.

There is a trap in this. If compression frees up room, the obvious thing is to fill it, and a smaller, fuller bag can end up heavier than the one you started with. Check your airline's size and weight limits for your ticket before you use the extra room, especially on a carry-on.

Where the real saving is: order

Most of what cubes save is time. With everything grouped, you stop digging.

• One cube per job. Tops in one, bottoms in another, underwear and socks in a small one. You open the cube you need and leave the others shut.
• Clean and worn apart. Midway through a trip, a spare cube becomes the laundry bag. The Compression Packing Cube Set of 4 is sold on exactly this: four compression cubes, so clean and worn clothes each get their own.
• Shoes on their own. Soles pick up dirt outside. A separate bag keeps them off everything else.
• Unpacking in one go. At the other end, cubes go straight into a hotel drawer, and back into the case the same way.

If you live out of one bag for a week, this is the part that makes the difference, not the centimetres.

How to pack a cube so the case closes

1. Fold or roll to the cube's width. Both work. Folding keeps shirts flatter; rolling suits T-shirts and knits. Either way, make each piece as wide as the cube so it fills the base without gaps.
2. Fill it evenly. A cube that is packed high at one end and empty at the other will not compress flat.
3. Close the main zip first, then the compression zip. Work the compression zip slowly, pressing the cube down with your other hand as you go.
4. Don't force it. If the zip is straining, take one thing out. A burst zip on day two costs more room than it ever saved.
5. Stand cubes on their edges. In a suitcase, cubes packed on their sides like files let you see every one from the top.
6. Heavy cubes at the wheel end. Shoes and denim near the wheels keep the case from tipping when it stands up.

Choosing a set

Size matters more than number. Before you buy, measure the inside of the bag you travel with and compare it with the cube sizes.

The Compression Packing Cubes, 5-Piece Set with Shoe Bag is the one with the fullest measurements on its page. It has four compression cubes and a shoe bag, all in polyester fibre fabric:

At 39 × 40 cm, the extra-large cube is too big for a small backpack; the listing says to skip the set if a small backpack is all you travel with. The care notes ask for hand washing and air drying.

The Compression Packing Cube Set of 4 comes in blue or pink polyester with compression zips. Its listing gives no cube sizes, and its notes say the fabric is for light moisture only.

The Compressible Packing Organizer Set of 4 takes a different shape: four compressible bags in assorted sizes with a vertical, multi-compartment layout, which suits accessories and small essentials alongside clothes. It is wipe-clean polyester, with no waterproof rating and no sizes given.

For shoes, the Breathable Mesh Travel Shoe Bag comes in two sizes, small at 21 × 33 cm and large at 25 × 40 cm, with a mesh panel so shoes can air out and a handle for carrying it on its own. It folds flat when it is empty.

And if your trips are longer stays rather than a new bed every night, the Collapsible Hanging Packing Organizer with Shelves works the other way round: you pack its shelves at home, then hang the whole thing from the wardrobe rail on arrival. It has no compression, so it organises rather than squeezes; its space saving is that it folds flat when it is not in use.

So, do you need them?

• If your case closes already and you just lose things in it, plain cubes or any set used without compressing will do.
• If the case is full, compression cubes help, most of all with soft clothes.
• If you are near your weight limit, cubes will not help, and the extra room is a reason to weigh the bag before you leave.
• If you travel with one small backpack, check cube sizes against it first. A big set may not fit at all.

Cubes are worth packing when they stop the digging. Any space they save is a bonus.