How we check
Where the airline limits and bag sizes come from, how the sides are compared, and what “fits if not packed full” means.
Where the numbers come from
Airline limits are copied from each airline’s own baggage page, never from other websites. Every airline page links to its source and shows the date we checked it. We keep the units the airline prints; where an airline prints one unit only, the other is our conversion and is marked with “≈”.
Bag sizes are the outside dimensions listed on the maker’s product page. We compare printed numbers with printed numbers: if the airline and the maker both print centimetres, we compare centimetres, so unit rounding never decides a verdict. When a maker prints inches and centimetres that really disagree (more than rounding), we use the larger value, so we never call a bag smaller than its maker does.
How we compare
- We sort the three sides of the bag and of the limit from largest to smallest and compare them in pairs, the way you would turn a bag to slide it into a sizer.
- Fits: every side is within the limit, and the sum of sides too when the airline publishes one (Delta: 45 in).
- Fits if not packed full: a soft backpack that is at most 3 cm too deep but fine on height and width. Makers list the depth packed full; packed less full a soft pack is thinner. It is never shown as a plain fit.
- Too big: anything else.
- Weight: where an airline has a weight limit we show how much is left for your things after the pack’s own empty weight.
What we do not know
Sizers at the gate, staff and aircraft differ, and a stuffed outside pocket adds depth. Gate agents have the final say. If you find a number that no longer matches the airline or the maker, tell us and we fix it.
Currently 18 airlines and 10 bags.