It decides two separate things: what snow the ski works in, and what brake width a binding needs. It is the only figure on a ski that appears twice in a purchase.
The snow half
The waist is the narrowest point of the ski, underfoot, in millimetres. It is the width that has to be tipped from one edge to the other, and the width that carries you in soft snow.
Roughly, and with every maker drawing the boundaries differently:
- Under about 80 mm is a piste ski. Quick edge to edge, grips hard snow, sinks in anything deep.
- 80 to about 95 mm is the all-mountain band: most people, most of the time, on most European pistes.
- Above about 100 mm is built for soft snow and is hard work on a groomed run.
The word on the listing — piste, all-mountain, freeride — is a shorthand for this number, and the number is the honest version.
The binding half
A binding’s brake width must be at least the waist of the ski, and not much more. A brake narrower than the ski will not mount; a brake far wider drags in a deep carve.
This is why the waist figure is worth writing down even if you buy a ski and a binding together: the day one of them is replaced, it is the number the shop asks for.
What it does not decide
The turn shape — that is the radius, and two skis of the same waist can have very different ones.
The flex — that is construction, and it is rarely published.
Your ability. A wide ski on a piste is slower to roll, which is a property of the ski, not a comment on the skier.
How this site prints it
Every ski page prints the three widths in millimetres as the maker publishes them, for the length being reviewed, and prints the radius beside them. Where the waist is unpublished — which is common — the page says so, because that silence is what makes the brake-width question unanswerable from a listing.
Where this page and a maker’s own documentation part company, the documentation is right. Every length, waist width, radius, flex index, last width, DIN range, brake width, filter category, temperature band and mass on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And the distinction this page keeps: a flex index describes the boot, not the person in it. No standards body defines the scale, no test produces a comparable figure between two makers, and the same number stiffens in the cold. This page reports the figure, names the maker who published it, and never ranks two boots on it alone.
The questions asked most often
Is a wider ski harder to learn on?
On a piste, yes: it takes longer to get from edge to edge, which is exactly what a beginner spends the week doing. In soft snow the same width is what keeps the ski up.
Where do I find the waist of a ski I already own?
Sometimes on the topsheet, as the middle of three numbers. Where it is not printed, a caliper at the narrowest point of the ski answers it in ten seconds.
Last reviewed 28 September 2026