This free suitcase volume calculator turns suitcase dimensions into litres. Enter length, width and depth in centimetres, and the tool gives the volume in litres and cubic inches, plus a usable volume estimate, so you compare bags by real capacity instead of marketing sizes.
Suitcase sizes like small, medium and large mean nothing consistent, because brands define them differently and one brand large can be smaller than another brand medium. Litres cut through that confusion, because a litre is a litre everywhere, and comparing two cases by litres tells you at once which one truly holds more.
To use the tool, enter your numbers in the fields above and press the calculate button. The results table updates at once, and you can change any number and calculate again as often as you like. Everything runs in your browser, so nothing you enter is sent to a server, and you need no account and no sign-up.
The formula multiplies length by width by depth in centimetres and divides by 1000 for litres, since one litre equals 1000 cubic centimetres. Cubic inches divide the same cubic centimetres by 16.387, and usable volume takes 90 percent of the total, because linings, handles and wheel housings eat about a tenth of the space.
Example: a case of 55 by 40 by 20 centimetres gives 44 litres, 2685 cubic inches, and a usable volume of 39.6 litres. That is a standard cabin case, and any case claiming far more litres at the same outside dimensions is counting wheels and pockets as packing space.
Tip: compare usable volume, not headline volume. Two cases can share a headline of 80 litres while one offers 72 usable litres and the other only 65, because thick shells and deep wheel housings steal space, so the usable number is the honest comparison.
Tip: measure the inside when you can. Outside dimensions include wheels, handles and corner guards, so an outside calculation overstates capacity by 5 to 10 percent, while inside dimensions give the space your clothes actually get.
Tip: match litres to trip length. Around 40 litres suits a cabin-only week, 60 to 80 litres suits one to two weeks checked, and over 100 litres suits family trips or long stays, so buy litres for the trips you take, not the trips you imagine.
Common question: How many litres is a cabin bag? A standard cabin bag of 55 by 40 by 20 centimetres is 44 litres outside and about 40 litres usable, which is the number most airlines implicitly allow, since their size limits and this volume match closely.
Common question: Why do two same-size cases claim different litres? Because makers measure differently: some use outside dimensions, some use inside, and some add pocket volume. Recalculate both from outside dimensions with this tool and the comparison becomes fair.
Common question: Should I buy the biggest case I can carry? No, buy the smallest case that fits your usual trip. A huge case invites overpacking, weighs more empty, and is harder to lift, store and manoeuvre, while a right-sized case keeps packing disciplined.
Packing well is a skill that pays off on every trip. A bag that is planned before you leave saves time at the hotel, avoids overweight fees at the airport, and leaves room for the things you bring home. Spend ten minutes with a plan and the whole trip feels calmer, from the first morning to the last evening.
This tool is free to use as often as you like. Bookmark it, run it before every trip, and let it carry the counting while you focus on the journey itself, the places you will see, and the people you will meet along the way.