How do I convert Altra shoe size to On?

Match by foot length in centimeters on each brand’s chart. Example: Altra US 10 ≈ On US 10.0 (about 27.2 cm). Model fit can still differ — check model guides.

Is a Altra US 10 the same as a On US 10?

Not always. Labels can map to slightly different foot lengths. Use the cm column, then adjust for the specific model’s fit.

Altra to On size conversion

Match sizes by foot length (cm), then check model fit — US labels alone can mislead across brands.

Chart match · verify brand charts

Check current prices · Lone Peak 8 Check current prices · Cloudmonster

(paid link)

Your Altra size (US)

Full converter (model + shoes you own) · Reverse: On → Altra

Altra → On chart

Static conversion table (crawlable). Interactive tool above uses the same cm matching.

Altra US	cm	On US	On EU
6.0	23.6	6.0	38.5
6.5	24.1	6.5	39.0
7.0	24.6	7.0	40.0
7.5	25.1	8.0	41.0
8.0	25.4	8.0	41.0
8.5	25.9	8.5	42.0
9.0	26.2	9.0	42.5
9.5	26.8	9.5	43.0
10.0	27.2	10.0	44.0
10.5	27.6	11.0	45.0
11.0	27.9	11.0	45.0
11.5	28.4	11.5	45.5
12.0	28.9	12.0	46.0
13.0	29.8	13.0	47.5

Model fit matters

Even when charts match, lasts differ. Check these guides:

Altra: Lone Peak 8

On: Cloudmonster · Cloud 5 · Cloudsurfer

Also compare Altra to: Salomon

Check prices: Altra On (paid link)

FAQ

How do I convert Altra shoe size to On?: Match by foot length in centimeters on each brand’s chart. Example: Altra US 10 ≈ On US 10.0 (about 27.2 cm). Then adjust for the specific model’s fit (runs big/small/narrow).
Is a Altra US 10 the same as a On US 10?: Not always. Labels can map to slightly different foot lengths. Use the cm column, then check model guides on both brands.
Which direction should I read first?: Start from the brand you already wear, then open the model fit pages linked below — lasts differ even when charts match.

Clothes sizing uses a separate compare path.