What this convention settles
Mondopoint sizes footwear by the length of the foot in millimetres or centimetres, optionally with a width. A ski boot marked 27.5 is intended for a foot of 275 mm. It is the sizing system the whole ski boot trade uses, and it is the reason a boot listing gives a number with a decimal point where a shoe would give 42.
Three ways of writing it appear on this shelf and all mean the same thing: 27.5, 275, and 27.5/28 or 28.5/29 for a shell moulded once and sold across two half sizes.
Snowboard boots use it too, and add a second figure that matters more for them: the outer length of the shell in centimetres, because that is what a binding has to hold and what decides whether a foot overhangs the board.
What it does not promise
It does not describe width. A 27.5 boot exists in a 98 mm last and a 102 mm last, and on a wide foot the second is a different product. Width is published separately, in millimetres across the ball of the foot, and it is the figure that decides comfort.
It does not convert reliably to a shoe size. The tables on listings are approximations made by the seller, and they differ.
It does not account for the liner. A new liner packs down over the first days, and a boot that is comfortable in a shop in October may be loose in January — which is what bootfitters mean when they say a boot should feel short at first.
It does not apply to the sole length a binding uses. That is a separate figure in millimetres, stamped on the heel, and a 27.5 boot from two makers can have two different sole lengths.
What it is read alongside
The alpine and touring boot sole standards, which describe the outside of the same boot, and the binding assembly procedure, which uses the sole length rather than this size.
Where it turns up on this site
Ski boots, snowboard boots and ice skates — skates being the shelf where the same number is quoted beside a shoe size most often, and most confusingly.
This site handles it in one way, consistently. A boot page prints the Mondopoint size as the maker publishes it, prints the last width in millimetres where one is stated, and prints the outer shell length for snowboard boots where the maker gives it. It does not convert any of them into a shoe size.
The questions asked most often
What is my Mondopoint size?
Measure the foot from heel to longest toe, in centimetres, standing, on paper, at the end of the day. That length is the number. A shop measures it in seconds and the measurement is free.
Why do some listings say 275 or 28.5/29?
The first drops the decimal point, the second gives a shell size that covers two half sizes — many shells are moulded once and fitted with two liners. Both are the same system written differently.
Should I size up for comfort?
A boot one full size too big cannot be fixed by tightening buckles, and the heel lift it allows is what ruins a day. The width of the last is what makes a boot comfortable, and it is a different figure.
Last reviewed 28 September 2026