Ultraboost Size Guide: Fit, Width & Size Chart

Runs half-size large

The Adidas Ultraboost runs half-size large. Start by checking half a size down from your usual US size. Available in standard (D) width only. Use the table below to convert your foot length in millimetres straight to US, UK, EU and CM sizes — the one measurement every system agrees on.

Best fit recommendation for Adidas Ultraboost

For a 268 mm foot, Adidas Ultraboost runs large. Best fit: US 9.5 (likely US 8.5–10.5), UK 8.5, EU 40, 26.5 cm — confidence 70%.

Recommended size for a 268 mm foot on Adidas Ultraboost (best fit + range, not a guarantee)
Best fit Likely range UK EU CM Confidence
US 9.5 US 8.5–10.5 8.5 40 26.5 70%

Evidence: 2 sources · no lab measurement in this record

See how we calculate for the methodology. Sizes vary by model and foot shape; this is an estimate, not a guarantee.

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Does the Ultraboost run true to size?

Across our data the Adidas Ultraboost runs half-size large. Start by checking half a size down from your usual US size.

Ultraboost size conversion chart

Ultraboost sizes by foot length. US Men's, US Women's, UK, EU and CM. The highlighted row is the model's true-to-size anchor.
Foot length US Men US Women UK EU CM
246.9mm 7 8.5 6 37 24.5
251.1mm 7.5 9 6.5 38 25
255.3mm 8 9.5 7 38 25.5
259.5mm 8.5 10 7.5 39 26
263.8mm 9 10.5 8 40 26.5
268mm 9.5 11 8.5 40 27
272.2mm 10 11.5 9 41 27
276.5mm 10.5 12 9.5 41 27.5
280.7mm 11 12.5 10 42 28
284.9mm 11.5 13 10.5 43 28.5
289.2mm 12 13.5 11 43 29

EU sizes are always rounded to a whole size — treat the EU column as the closest honest match.

Ultraboost width availability

Available in standard (D) width only.

Only the standard (D) width is offered, so very wide or very narrow feet may need to adjust length or choose a brand with more width grades.

Expert fit notes

The Ultraboost runs longer and narrower than a true US fit: the Primeknit upper is snug across the midfoot while the last itself is slightly long. Narrow feet often stay true to size, but many wearers find the length generous and drop half a size for a locked-in feel. Wide feet should be cautious — the knit upper has limited give and there is no wide option.

Where this data comes from

Built from 2 sources and 1,320 measurements. See how we calculate for how confidence is scored.