Wondering what a men size 9 in women works out to? Here's the short answer: in standard US sizing, a men's 9 is approximately a women's 10.5. That's because most US footwear brands — especially athletic ones — separate the two scales by 1.5 sizes on the same length of foot. The long answer is a little more interesting, because widths, brand conventions, and international sizing all complicate the picture. This guide gives you the full conversion list, explains why the offset exists, and covers the fit details that actually determine whether a cross-scale shoe works for you.
The quick answer, and why it's 1.5 sizes
US men's and women's shoe sizes both measure foot length, but the scales are offset: the same physical length carries a number 1.5 higher on the women's scale. So a men's 9 and a women's 10.5 are (in theory) the same length of shoe. The offset is pure labelling convention, dating back to how US lasts were standardised — there's nothing anatomical about the number itself.
One important caveat before the list: this 1.5-size rule is the athletic and mainstream standard. Some fashion and comfort brands use a 1-size offset instead, and plenty of small brands publish their own charts. The rule gets you to the right neighbourhood; the brand's own size chart gets you to the right house. When a brand publishes both scales or a unisex chart, trust it over any generic formula.
Men's to women's shoe size conversion (US)
Using the standard 1.5-size offset, here's the full conversion both directions:
- Men's 5 = Women's 6.5
- Men's 5.5 = Women's 7
- Men's 6 = Women's 7.5
- Men's 6.5 = Women's 8
- Men's 7 = Women's 8.5
- Men's 7.5 = Women's 9
- Men's 8 = Women's 9.5
- Men's 8.5 = Women's 10
- Men's 9 = Women's 10.5
- Men's 9.5 = Women's 11
- Men's 10 = Women's 11.5
- Men's 10.5 = Women's 12
- Men's 11 = Women's 12.5
- Men's 11.5 = Women's 13
- Men's 12 = Women's 13.5
Reading it the other way: a woman who wears a US women's 10.5 would take roughly a men's 9; a women's 9 maps to about a men's 7.5, and so on — just subtract 1.5 from the women's number.
Length is only half the fit: the width problem
Two shoes can be exactly the same length and fit completely differently — because men's and women's shoes are built on different lasts.
US widths run on a letter scale, and the "default" differs by scale: a standard men's width is D, while a standard women's width is B. Beyond the letters, men's lasts are generally cut wider through the heel, midfoot, and toe box. Practical consequences:
- Women buying men's shoes (common for wide feet or particular colourways): the length conversion gets you close, but expect a roomier heel and forefoot. If you normally wear a wide (D) women's width, a men's standard width often fits beautifully.
- Men buying women's shoes: subtract 1.5 for length, but a standard women's B width will feel narrow to most men. Look for styles offered in wide, or styles with inherently forgiving construction.
- Kids' crossover bonus: a US big-kids' size roughly equals the same men's number (a men's 7 is close to a big kids' 7), which is a classic money-saver for smaller sizes.
International sizing in one minute
UK sizing typically sits about one size below US men's (a US men's 9 is around a UK 8), and EU sizing uses a single unisex scale where a US men's 9 lands around EU 42–42.5. Both vary by brand, so the golden rule stands: measure your foot in centimetres and use each brand's own chart whenever one exists. Foot length in cm is the only number that never lies.
Tips for cross-shopping between men's and women's styles
- Measure both feet, in the afternoon. Feet swell during the day and most people have one foot slightly longer; fit the larger foot.
- Apply the 1.5 rule, then verify against the brand's chart. Where the two disagree, the brand wins.
- Think in width as much as length. If a converted shoe fits in length but slips at the heel or pinches at the forefoot, the last — not the number — is the problem.
- Favour forgiving constructions when converting. Flexible, moulded, or stretchy shoes absorb conversion error far better than stiff, structured ones. This is one reason moulded EVA and bio-based foam shoes are so easy to cross-shop — brands like Floafers, which builds its waterproof slip-on loafers for men, women, and kids in soft sugarcane-based EVA foam, leave a lot more margin than a rigid leather dress shoe would; you can browse the Floafers family lineup here or read our full Floafers review.
- Check the return policy before you experiment. Cross-scale sizing is exactly the situation free exchanges were made for.
When the conversion doesn't matter much at all
Some footwear categories are naturally low-stakes for conversion because the fit is contoured rather than clamped. Okabashi — the Georgia-based maker of 100% American-made, recyclable sandals and flats — designs styles like its Morgan T-strap slide around a contoured, arch-supporting footbed with an adjustable back strap and a shape designed for a wide range of foot shapes, which makes landing your exact converted size far less critical than in a closed athletic shoe. Several of its styles are even noted as running large and wide — useful knowledge when you're translating across scales. See our Okabashi review for the brand story, our Okabashi footbed buying guide for style-by-style fit notes, or shop the Okabashi range directly. And if you're weighing the two brands against each other, our Floafers vs Okabashi comparison breaks down exactly who each suits.
The bottom line
A men's size 9 is a women's 10.5 in standard US sizing — add 1.5 going men's-to-women's, subtract 1.5 coming back. But treat that as a starting point, not a verdict: confirm against the brand's own chart, respect the width differences between men's and women's lasts, and when you're experimenting across scales, favour flexible constructions and friendly return policies. Get those three things right and the number on the box stops mattering — the fit does.