Last width & foot volume
By Sierra Marlowe · Fit, Sizing & Standards
Ski boot fit lives or dies on two measurements most buyers never check: last width and internal volume. Here's what they mean, how to measure your foot, and which boots tend to match — from a former ski-shop equipment buyer. For a personalized number, run the Boot Fit Engine.
What "last width" really means
The last is the internal width of the boot shell at its widest point — the forefoot — measured in millimeters. It's the single most important spec for whether a boot will fit your foot without pressure points (Blizzard-Tecnica size guide).
Last is always referenced at mondo size 26/26.5. So when a boot is listed as "100mm," that means the shell is 100mm wide at size 26.5 — not at your size (The Ski Monster). Adult boots typically range from about 95mm (race/narrow) to 106mm+ (extra-wide), with the vast majority sitting between 98 and 102mm (Outdoor Gear Lab, Level Nine Sports).
The 2mm-per-size rule
Here's the part that trips people up: the published last is at size 26.5. For every shell size up or down, the actual width changes by about 2mm. A "100mm" boot is roughly 98mm at size 25.5, 102mm at 27.5, and 104mm at 28.5 (The Ski Monster).
That means you can't compare your bare-foot measurement to the published 26.5 number directly — adjust for your mondo size first, then compare.
How to measure your foot width
- Stand on a piece of paper with your full weight on both feet. Trace each foot with a pen held vertically (PTO Ski).
- Measure the widest point — across the ball of the foot, from the outside of the big-toe joint to the outside of the pinky-toe joint — in millimeters.
- Do it at the end of the day, when feet are largest. Measure both feet and use the larger one.
- Add ~2mm per shell size above 26.5 (or subtract below) so you're comparing to the last at your size.
Aim for the boot last to be slightly wider than your bare-foot measurement — you need clearance, and a shop can always snug a roomy boot or punch a tight spot, but they can't easily shrink one that's too wide.
Last-width bands & example boots
| Band | Last (mm) | Foot type | Example models |
|---|---|---|---|
| Narrow / Low volume | 95–98 | Slim forefoot, low instep | Lange RX/RS (97), Tecnica Mach1 LV (98), Salomon S/Max (98), Fischer RC4 (97) |
| Medium | 99–102 | Average — most skiers | Salomon S/Pro (100), Atomic Hawx Prime (100), Nordica Speedmachine 3 (100), K2 Recon (100), Tecnica Mach1 MV (100) |
| Wide / High volume | 102–104 | Broad forefoot, high instep | Nordica Sportmachine 3 (102), Salomon S/Pro HV (102), Dalbello Panterra (100–102), Tecnica Mach1 HV (103), K2 BFC (103), Head Formula (103) |
| Extra-wide | 105+ | Very wide / very high volume | Select HV/freeride models; consider a bootfitter |
Last widths above are referenced at mondo 26.5. Sources: Blizzard-Tecnica, REI, Backcountry, Salomon, Outdoor Gear Lab, Wayfinder Boots.
Foot volume, explained
Volume combines last width with instep height to describe how snug or roomy the whole fit is (The Pro Ski & Ride). Most brands label boots LV (low volume), MV (medium), and HV (high volume):
- Low volume — narrow last + low instep. Race/performance feel: snug, responsive.
- Medium volume — the most common starting point. Balanced for average feet.
- High volume — wide last + high instep. Comfort/freeride feel: roomier, more forgiving.
The Boot Fit Engine computes your volume class from your foot width, instep, weight, and ability — then matches brands that tend to fit that profile.
Run the Boot Fit EngineBrand last-width reference
Most major brands now offer a narrow (LV), medium (MV), and wide (HV) last across their all-mountain lines (Bootfitters). Here's where the popular models land:
| Brand | Narrow (LV) | Medium (MV) | Wide (HV) |
|---|---|---|---|
| Tecnica | Mach1 LV — 98mm | Mach1 MV — 100mm | Mach1 HV — 102–103mm |
| Lange | RX/RS — 97mm | RX MV | LX (wide) |
| Salomon | S/Max — 98mm | S/Pro — 100mm | S/Pro HV — 102mm |
| Atomic | Hawx Ultra — 98mm | Hawx Prime — 100mm | Hawx Magna — 102mm |
| Nordica | Dobermann (race) | Speedmachine 3 — 100mm | Sportmachine 3 — 102mm |
| Head | Raptor — 98mm | Edge — 100mm | Formula — 103mm |
| Dalbello | DS Asolo (narrow) | DS — 100mm | Panterra — 100–102mm |
| Fischer | RC4 — 97mm | The Curv | The Curv (wide) |
| K2 | Recon LV | Recon — 100mm | BFC — 103mm |
Lasts vary by model year and are referenced at 26.5. Sources: Blizzard-Tecnica, Salomon, REI, Outdoor Gear Lab, Wayfinder Boots, Backcountry, evo.
If your foot is…
- Narrow + low instep → LV boots: Tecnica Mach1 LV (98mm), Lange RX/RS (97mm), Salomon S/Max (98mm). Expect a snug, performance-oriented fit.
- Average width + average instep → MV boots: Salomon S/Pro (100mm), Atomic Hawx Prime (100mm), Nordica Speedmachine 3 (100mm), K2 Recon (100mm). The widest range of options.
- Wide + high instep → HV boots: Nordica Sportmachine 3 (102mm), Salomon S/Pro HV (102mm), Dalbello Panterra (100–102mm), K2 BFC (103mm), Head Formula (103mm). Roomier and more forgiving.
Shells can be punched or stretched at pressure points — heat-moldable shells like Tecnica CAS, Salomon Custom Shell, and Atomic Adaptive Fit are specifically built for a shop to widen (Bootfitters). Start with the closest last and let a bootfitter fine-tune.
Browse current models at retailers like Backcountry. When our affiliate program is live, qualifying purchases may earn a commission — see our affiliate disclosure.
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