Luggage Size Calculator
Will my bag fit? Enter your bag and the allowance from your booking to see each side, the total size and the weight checked, and how much you’re over.
Wheels and handles go on the tallest side; pockets go on the depth (the shortest side).
Match the sides“Any way round” checks your longest side against the longest limit, and so on. Pick “in the order typed” if the bag must stand a set way in the sizer.
Piece concept: a set number of bags, each up to its own limit. Weight concept: one total weight shared by all your bags. Your fare says which applies.
Weights in kg each. They come off the weight you have left.
How your bag is checked
Measure the bag at its biggest points, add the three sides, check each side against the limit, then weigh it.
- 1
Measure it all
54 × 38 × 23 cmwheels included
- 2
Add the sides
54 + 38 + 23= 115 cm45.28 in · 47.2 L
- 3
Check each side
23 vs 20 cm→ 3 cm over
- 4
Weigh it
7.8 vs 7 kg→ 0.8 kg over
Read more: the formula, a worked example, example sizes and packing tips
Airlines limit bags in two ways: by size (either three maximum sides, like 55 × 40 × 20 cm, or one maximum total of length + width + height, often called linear inches or linear centimetres) and by weight. This calculator checks your bag against the numbers you type in from your booking. It doesn’t know any airline’s rules, because they vary by route and fare and change often.
The formula
linear size = length + width + height
volume in litres = length × width × height in cm ÷ 1,000
with three limits: sort both from longest to shortest; each side must be no more than its limit
over = your side − the limit (when it’s bigger)
with a total limit: linear size must be no more than the limit
weight over = bag weight − max weight; weight left = max weight − bag weight − items still to pack
1 inch = 2.54 cm · 1 lb = 0.45359237 kg
Worked example
A bag measures 54 × 38 × 23 cm with its wheels and weighs 7.8 kg. The example limit is 55 × 40 × 20 cm and 7 kg.
- Linear size = 54 + 38 + 23 = 115 cm, which is 115 ÷ 2.54 = 45.28 in.
- Volume = 54 × 38 × 23 = 47,196 cm³ ÷ 1,000 = 47.2 litres, about 47.196 ÷ 44 = 1.07 times a 55 × 40 × 20 cm (44 litre) bag.
- Longest side 54 cm against 55 cm: fits, 1 cm spare. Middle side 38 cm against 40 cm: fits, 2 cm spare. Shortest side 23 cm against 20 cm: 3 cm over (1.18 in).
- Weight 7.8 kg against 7 kg: 0.8 kg over (0.8 ÷ 0.45359237 = 1.76 lb). The bag weighs 7.8 ÷ 0.45359237 = 17.2 lb.
The limit’s own total is 55 + 40 + 20 = 115 cm, exactly the same as the bag’s. So the bag passes on the total but still won’t go into a 20 cm deep sizer: when the limit is given as three sides, every side counts. Take 0.8 kg out and squash the front to 20 cm, or use a slimmer bag.
Example sizes on this page
| Button | Size | Same as | Weight |
|---|---|---|---|
| Under-seat bag | 40 × 30 × 15 cm | 15.7 × 11.8 × 5.9 in · 18 L | — |
| Cabin bag | 55 × 40 × 20 cm | 21.7 × 15.7 × 7.9 in · 44 L | 7 kg (15.4 lb) |
| Carry-on (inches) | 22 × 14 × 9 in | 55.9 × 35.6 × 22.9 cm · 45.4 L | — |
| Checked bag | 158 cm total | 62.2 in total | 23 kg (50.7 lb) |
| Checked (inches) | 62 in total | 157.5 cm total | 50 lb (22.7 kg) |
These are generic example sizes, not any airline’s allowance. Real limits vary by airline, route, fare, cabin and aircraft, and they change: always check your own booking. Written 14 October 2026.
Rough bag sizes by volume
- Up to 25 litres: small backpack or under-seat bag.
- 25 to 50 litres: typical cabin bag or carry-on.
- 50 to 80 litres: medium checked suitcase.
- 80 to 110 litres: large checked suitcase.
- Over 110 litres: extra-large case or trunk.
Several bags: piece or weight
Say you have two bags of 20 kg and 12 kg. With a piece concept of two bags at 23 kg each, both pass: 3 kg and 11 kg spare. With a weight concept of 30 kg in total, you’re 20 + 12 − 30 = 2 kg over, even though each bag is light enough on its own. With only one bag allowed, the second one is an extra piece.
Packing tips
- Weigh the empty bag first: many cabin cases weigh 2 to 3.5 kg before anything goes in.
- Soft front pockets bulge when full. Measure the depth when the bag is packed, not empty.
- Wear your heaviest shoes and jacket, and keep chargers and power banks in your cabin bag.
- A luggage scale is cheap and saves surprises; home bathroom scales also work if you weigh yourself with and without the bag.
A guide for planning. Airlines, sizers and staff at the gate have the final say, and some fares allow only a small personal item.
Common questions
How do I measure my luggage?
Stand the bag up and measure its height from the floor to the top of the handle (with the handle pushed down), its width across the widest point, and its depth front to back including pockets. Include the wheels and any handles: airlines and bag sizers measure the outside of everything.
What are linear inches or linear centimetres?
The length, width and height added together. A 54 × 38 × 23 cm bag is 54 + 38 + 23 = 115 linear cm, which is 115 ÷ 2.54 = 45.28 linear inches. Many checked bag limits are given this way.
Can my bag be under the linear total but still too big?
Yes. If the limit is given as three sizes, each side has to fit. A 54 × 38 × 23 cm bag adds up to 115 cm, the same as 55 × 40 × 20 cm, but it is 3 cm too deep, so it would not go in a 20 cm deep sizer.
What is the piece concept and the weight concept?
Under a piece concept you may take a set number of bags, each up to its own weight and size limit. Under a weight concept you get one total weight to share across all your bags. Which one applies depends on the airline, route and fare, so check your booking.
How many litres is a carry-on?
A 55 × 40 × 20 cm bag holds 55 × 40 × 20 ÷ 1,000 = 44 litres. Most cabin bags are somewhere around 30 to 50 litres; medium checked cases are often 50 to 80 litres.
Are these airline allowances?
No. The quick-fill buttons are example sizes only. Allowances vary by airline, route, fare and even aircraft, and they change, so type in the numbers from your own booking or the airline’s website.
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Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.