How to pack for a week in a 40 x 30 x 20 cm bag

A week fits in a 40 x 30 x 20 cm bag if you plan for four tops, two bottoms, one layer and one spare pair of shoes, wear the bulkiest items on the plane, and pack clothes into two or three compression cubes. Toiletries go in a clear bag at the top so security is quick.

Start with the bag itself

40 x 30 x 20 cm is the free under-seat limit on Ryanair, Wizz Air, Vueling and Jet2's small bag. That is about 24 litres. A soft backpack uses nearly all of it; a wheeled case loses 2 to 3 cm to wheels and handle. Before you pack, measure the empty bag. If it is already at the limit, a full front pocket will push it over.

What to take for seven days

Plan for doing a small wash once, in the sink or a hotel laundry, and the list shrinks:

4 tops that all go with both bottoms
2 bottoms, one of which you wear on the plane
1 warm or waterproof layer, worn on the plane
5 sets of underwear and socks; thin running socks pack smallest
1 pair of light shoes or sandals, plus the pair you travel in
Sleepwear that doubles as a spare top
Swimwear if you need it: it takes almost no room

Pick one colour family so everything matches. Two neutral bottoms and four tops give you eight outfits.

Fold, roll or cube?

Rolling works for t-shirts and soft trousers. Folding is better for shirts. Packing cubes beat both for a small bag, for three reasons: they keep each type of clothing together, they stop the bag losing its shape as you take things out, and compression cubes squeeze out air with a second zip so the same clothes take up less depth. Two medium cubes and one small cube fill a 40 x 30 x 20 cm bag neatly, with the gaps along the edges left for chargers and socks.

Wear the bulk

Your heaviest shoes, jeans and jacket should be on you, not in the bag. A jacket with deep pockets can carry a phone, passport, earphones and a book through the gate. Airlines measure the bag, not what you are wearing.

Liquids and electronics

Keep liquids in a clear resealable bag at the very top. Liquid rules at security depend on the airport and the scanners it uses, so check your departure airport before you fly; many still apply a 100 ml limit per container. Put the laptop or tablet against the back panel of the bag, where it is protected and easy to take out.

Check it before you leave

Measure the packed bag standing upright, including anything strapped to the outside, and compare it with your airline. A soft bag that is 1 cm over can usually be pressed into the sizer. A hard one cannot. If you are close to the limit, take out the spare shoes first: they are the single largest item in most bags.