How many days fit in a weekender, by litres

What a litre holds

A folded shirt is about 1.5 litres. A pair of trousers is 3. A rolled jumper is 4. A pair of shoes, in the bag rather than on your feet, is 6 to 8 depending on the sole.

That arithmetic is why a 28-litre bag is a two to three-day bag and not a four-day one, whatever the marketing on a bag of that size usually says.

The three sizes, in days

These assume one person, one pair of shoes worn rather than packed, and a toiletry bag.

• 28 litres: two to three days. Two shirts, one pair of trousers, a jumper, underwear, toiletries.
• 38 litres: four to five days. Add a second pair of trousers, a spare pair of shoes and a jacket.
• 45 litres: a week, if there is a washing machine at the other end.

Why the last 10 percent matters

A leather weekender compresses. Packed to 90 percent it gives at the sides and goes into a cabin sizer; packed to the zip it does not, and the difference is a gate fee.

This is also the argument against packing cubes in the top layer. They hold the shape you want the bag to lose.

Check the outside dimensions too

Litres tell you what goes in. Centimetres tell you whether the airline takes it. Every bag we make lists both, along with its weight empty, because 2.1 kg of bag comes out of a 10 kg cabin allowance before anything is packed.