On to Under Armour Shoe Size Conversion

Switching from On to Under Armour? On runs true to size and Under Armour runs small, so the size you order changes. Here's the full chart.

A On 9 works out to a Under Armour 9.5 — about half a size up. The chart below has every size.

On → Under Armour: size up half a size

A On 9 is a Under Armour 9.5.

Find your On size on the left, read across for Under Armour:

On size	Under Armour size	UK	EU	Foot (cm)
6.5	7	5.5	37	23.5
7	7.5	6	38	24.3
7.5	8	6.5	38.5	24.7
8	8.5	7	39.5	25.1
8.5	9	7.5	41	25.9
9	9.5	8	41.5	26.3
9.5	10	8.5	42.5	26.7
10	10.5	9	43	27.1
10.5	11	9.5	43.5	27.5
11	11.5	10	44	27.9
11.5	12	10.5	44.5	28.3
12	12.5	11	45.5	28.7
12.5	13	11.5	46	29.1
13	13.5	12	47	29.5
13.5	14	12.5	47.5	29.9
14	14.5	13	48	30.3
14.5	15	13.5	49	31.1
15	15.5	14	49.5	31.5

⚠️ Fit varies by model. On (On Running) runs true to size for most, with a snug, performance fit. Under Armour tends to run about half a size small, especially in performance trainers.

Under Armour to On → · On chart · Under Armour chart · Brand finder

What is a On 9 in Under Armour?

A On 9 is about a Under Armour 9.5 — they share a foot length of roughly 26.3 cm (UK 8, EU 41.5).

Do On and Under Armour fit the same?

No — On runs true to size and Under Armour runs small, so size up half a size when you switch.

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