What Suitcase Size Do I Need? The Complete Liter Guide

Too small, and the lid only closes by force. Too big, and you pay a checked-bag fee for half a case of empty air. The right suitcase size is not a matter of taste but simple arithmetic based on trip length, type of travel and airline rules. Here is the complete overview.

Suitcase sizes at a glance

Suitcase capacity is given in liters. As a rule of thumb: roughly 10–15 liters per travel day — pack minimally and you will need considerably less.

• Carry-on (cabin), 30–45 l: 1–4 days — city break, business trip
• Size M (check-in), 60–75 l: about one week
• Size L, 85–100 l: two weeks and more, family vacation

Carry-on: the size that is almost always enough

For most trips of up to four days a good carry-on is all you need — and you save yourself the baggage carousel, the checked-bag fee and the risk of lost luggage. The Altair Original Cabin is built to the common carry-on dimensions (55 × 40 × 23 cm) and uses the permitted volume right into the corners — an aluminum shell does not need bulging soft pockets to create space.

With compression packing cubes a surprising amount goes in: 4–5 outfits, shoes, a toiletry bag and a laptop are no problem for the practised packer. We show you how in our guide “How to pack a suitcase like a pro”.

When a large suitcase is worth it

From about a week of travel, for a winter holiday (bulky clothes!) or with children there is hardly any way around checked baggage. Two notes from experience:

• Count the empty weight: with a 23 kg allowance every kilo of suitcase matters. Before the return flight the Altair Digital Luggage Scale gives you certainty — before it gets expensive at the desk.
• Large cases travel in the hold: a tracker in the inner pocket shows you where your luggage is at any moment.

When a bag or backpack is the better choice

Not every trip needs wheels:

• Weekend trip by car or train: the Altair Leather Travel Bag holds everything for 2–3 days, sits softly in the trunk and looks better doing it than any trolley.
• As your personal item on the plane: the Altair Travel Backpack fits under the seat in front — the clever complement to a cabin case when the airline allows only one piece in the cabin.
• The frequent-flyer combination: cabin case + backpack covers practically everything from a day meeting to a week away.

The three rules of thumb

• ✔ 10–15 liters per travel day — minus 30 % if you compress with packing cubes.
• ✔ When in doubt, go smaller: a full small case travels better than a half-empty large one.
• ✔ Check the airline first, then pack: you will find the current carry-on dimensions of all major airlines in our carry-on guide 2026.

Choose the size correctly once and you pack faster, travel lighter — and never argue at the gate again.