Select shoe size or foot length, then choose a sizing category. This reproduces the page’s simplified legacy US formulas in inches or centimeters; it does not guarantee fit or identify a child’s C/Y range.

Simplified legacy US formula estimate. Brand sizing and fit vary; check the maker’s foot-length chart. Children’s formula does not map C/Y ranges or their size-number restart.

Men’s legacy formula estimates ↔ Foot length (in; rounded)
Foot Length to US Size (Men) US Size (Men) to Foot Length
9.67 in = US men’s 7US men’s 8.5 = 10.17 in
9.83 in = US men’s 7.5US men’s 9 = 10.33 in
10.00 in = US men’s 8US men’s 9.5 = 10.50 in
10.17 in = US men’s 8.5US men’s 10 = 10.67 in
10.33 in = US men’s 9US men’s 10.5 = 10.83 in
10.50 in = US men’s 9.5US men’s 11 = 11.00 in
10.67 in = US men’s 10US men’s 12 = 11.33 in
10.83 in = US men’s 10.5US men’s 7 = 9.67 in
11.00 in = US men’s 11US men’s 7.5 = 9.83 in
11.33 in = US men’s 12US men’s 8 = 10.00 in
Formulas (Men): US = 3×L(in) − 22; L(in) = (US + 22) ÷ 3.
Women’s legacy formula estimates ↔ Foot length (in; rounded)
Foot Length to US Size (Women) US Size (Women) to Foot Length
9.00 in = US women’s 6US women’s 7.5 = 9.50 in
9.17 in = US women’s 6.5US women’s 8 = 9.67 in
9.33 in = US women’s 7US women’s 8.5 = 9.83 in
9.50 in = US women’s 7.5US women’s 9 = 10.00 in
9.67 in = US women’s 8US women’s 9.5 = 10.17 in
9.83 in = US women’s 8.5US women’s 10 = 10.33 in
10.00 in = US women’s 9US women’s 11 = 10.67 in
10.17 in = US women’s 9.5US women’s 6 = 9.00 in
10.33 in = US women’s 10US women’s 6.5 = 9.17 in
10.67 in = US women’s 11US women’s 7 = 9.33 in
Formulas (Women): US = 3×L(in) − 21; L(in) = (US + 21) ÷ 3.

Shoe Size Formula

The following three legacy formulas give arithmetic estimates from heel-to-toe foot length L in inches. They are not universal brand sizing standards. The child offset does not model the C/Y range transition or size-number restart; use a manufacturer’s children’s chart for fitting.

USM = (3 × L) - 22
USF = (3 × L) - 21
USC = (3 × L) - 9.67
  • Where L is the length in inches
  • USM is men's size
  • USF is women's size
  • USC is the legacy child-formula output, not a verified C/Y shoe size

Shoe Size Definition

A shoe size is a standard way of displaying the length of a shoe so that people can more easily understand the proper size for their feet.

Shoe Size Example

How to calculate shoe size

  1. First, measure your foot

    Measure the length of your foot from heel to toe in inches.

  2. Select the proper formula

    Select the intended footwear sizing category; it does not infer personal gender.

  3. Calculate your shoe size

    Calculate the formula estimate, then check the manufacturer’s foot-length chart and fit.

FAQ

How do I accurately measure my foot for shoe sizing?
To accurately measure your foot, place your foot on a piece of paper and draw around it. Measure the length from the heel to the longest toe in inches. This measurement is what you'll use in the shoe size calculator.

Can these formulas be used for all types of shoes?
While these formulas provide a general guideline for shoe sizing, different types of shoes (like athletic vs. dress shoes) may fit differently. It's always recommended to refer to specific brand sizing charts when available.

What if my foot measurement is between sizes?
If your foot measurement falls between sizes, it's generally recommended to go with the larger size for comfort, especially if you plan to wear socks with your shoes.

Is there a difference in shoe sizing internationally?
Yes, shoe sizes can vary significantly between different countries. The formulas provided are primarily for US shoe sizes. If you're purchasing shoes from international brands, you may need to consult a global shoe size conversion chart.