Stop Guessing Your Size When Ordering Online
Shoe sizes are famously inconsistent — a 9 in one brand is an 8.5 in another, and US, UK and EU numbers look nothing alike. The one thing that doesn’t lie is your foot’s actual length. This free calculator converts a simple heel-to-toe measurement into US, UK and EU sizes for men and women, with the formulas shown so you can verify everything.
Measure once, enter the number, and shop with confidence. No signup, everything runs privately in your browser.
Foot length → US / UK / EU
Please enter a foot length between 5 and 15 inches (13–38 cm).
Your estimated shoe size
A starting point, not a fitting. Brands cut lasts differently — athletic shoes often run small, dress shoes narrow. When between sizes, size up for sneakers and check the brand’s own chart for boots and heels.
How to Measure Your Foot
- Trace it. Stand on a piece of paper (socks on, weight fully on the foot) and trace around it, pen held vertical.
- Measure heel to longest toe with a ruler — not always the big toe. Do it late in the day, when feet are at their largest.
- Use the larger foot if they differ, and enter the length above in inches or centimeters.
The Formulas
US Women’s = 3 × L − 21
UK = 3 × L − 23
EU ≈ 1.27 × (UK + 23) + 2
L = foot length in inches. Results rounded to the nearest half size (EU to whole).
Worked example: a man’s 10-inch foot. US = 3 × 10 − 22 = 8. UK = 30 − 23 = 7. EU ≈ 1.27 × 30 + 2 = 40. A woman’s 9.5-inch foot: US = 3 × 9.5 − 21 = 7.5.
Quick Conversion Chart
| Foot (in) | Foot (cm) | US Men | US Women | UK | EU |
|---|---|---|---|---|---|
| 9.5 | 24.1 | 6.5 | 7.5 | 5.5 | 38–39 |
| 10.0 | 25.4 | 8 | 9 | 7 | 40–41 |
| 10.5 | 26.7 | 9.5 | 10.5 | 8.5 | 42–43 |
| 11.0 | 27.9 | 11 | 12 | 10 | 44–45 |
Who Needs This
- Online shoppers buying shoes without a fitting room.
- International buyers converting between US, UK and EU listings.
- Parents checking kids’ sizes at home (measure monthly — they grow fast).
- Anyone between sizes who wants the math before choosing up or down.
Fit tips
- When between sizes, size up for sneakers and check the brand chart for dress shoes.
- Width matters as much as length — if shoes always pinch the sides, look for wide (W/EE) fittings.
- Try shoes on in the afternoon; feet swell through the day.
Why US and EU Sizes Never Line Up Exactly
The mismatch is built into the rulers. US and UK sizes step by one barleycorn — a third of an inch (8.47 mm) — while EU sizes step by one Paris point, two-thirds of a centimetre (6.67 mm). Different step sizes and different starting points mean no single “add 33” rule works at every size, which is why honest charts show ranges like EU 42–43.
Frequently Asked Questions
How do I know my shoe size without trying shoes on?
Measure your foot from heel to longest toe and convert with the formulas above: US Men’s = 3 × length(in) − 22. That gives your baseline; brand fit varies around it.
Are men’s and women’s shoe sizes the same?
No — for the same foot length, women’s US sizes run higher in number than men’s (a men’s 8 works out to about a women’s 9 on the formulas above, and many brands label it 9.5). UK and EU systems are unisex.
How do US shoe sizes convert to EU?
Roughly: EU ≈ 1.27 × (UK + 23) + 2, where UK = 3 × inches − 23. A US men’s 9 is about EU 42–43. Always check the brand’s chart for the final call.
Why do sizes differ between brands?
Each brand cuts its “last” (the foot-shaped mold) slightly differently, and targets different fit philosophies — running brands often run small, fashion brands narrow. Your measured length is the constant; the size number is the variable.
Should I measure with socks on?
Yes — measure wearing the socks (or sock thickness) you’ll actually wear with the shoes.
How much growing room do kids need?
About a thumb’s width — roughly 0.5 inch (1.3 cm) — beyond the longest toe. Re-measure every 2–3 months for young children.
What is my shoe size in Japan (Mondopoint)?
Japanese sizes are your foot length in centimetres. A 26.7 cm foot is JP 26.5–27; a 24.1 cm foot is JP 24. It is the most direct system of all — no formula needed.
Final Thoughts
Your feet don’t care what number is printed on the box — they care about millimeters. Measure the foot, trust the math, and use the size number as a starting point for the brand’s chart, not the final word.
Try our BMI calculator for healthy ranges.