How this conversion works
Korean and Japanese shoe sizes are simply your foot length in millimeters (a size "270" means a 270 mm / 27.0 cm foot) — no conversion needed. US, UK, and EU sizes use different numbering scales built around that same physical length, anchored at the common reference point of a 270 mm foot = US Men's 9 = UK 8 = EU 42.5.
- mm — foot length in millimeters = KR/JP size
- 10 mm — the KR/JP 5 mm half-size interval = one US half size
More detail
Why women's US sizes differ from UK and EU
In the US, men's and women's shoes use separate numbering scales — a women's US size is conventionally about 1.5 sizes higher than the men's number for the same foot length. The UK and EU, by contrast, largely share one physical scale across genders (the number describes the same length; only the last shape differs), which is why this calculator keeps UK and EU size the same regardless of the "for" selection, but shifts the US size.
Why the numbers won't match every brand exactly
Shoe sizing has no single global standard — each brand builds its own "last" (the foot-shaped mold a shoe is built on), and add different amounts of internal room. That's why converters (including this one) can be off by half a size or more compared to what's printed inside a specific pair. Treat the result as a starting point, then check reviews or the brand's chart for a known-tricky size.
Fitting tip. Measure both feet in the evening — feet swell over the course of a day and rarely match exactly — and always convert from your longer foot's length, not the shorter one.
Frequently asked questions
What US size is a 270mm (KR/JP) shoe?
For men's, 270mm converts to US 9 exactly — enter 270 above with "Men's" selected to confirm. For women's, the same 270mm foot converts to US 10.5, since women's US sizing runs about 1.5 sizes higher for the same length.
Is UK shoe size the same for men and women?
Largely yes — unlike the US, the UK doesn't use a separate women's number scale, so a 270mm foot converts to UK 8 regardless of the "for" selection above. Only the shoe's last shape (width, toe box) differs by gender, not the size number.
Does the same US 9 fit the same across shoe types?
Not always — even within one brand, a running shoe in US 9 tends to run true to size, while a dress loafer or flat in the same labeled size often fits about half a size smaller because of how the last is shaped for that style. If a specific pair feels off from this calculator's result, that's often the style, not a sizing error.
How do I measure my foot length in mm to use this calculator?
Stand on a piece of paper, mark your longest toe and heel, and measure the distance in millimeters. That number is your KR/JP size directly — enter it above to get US/UK/EU equivalents.