Shoe Size Converter Calculator Formula
Understand the math behind the shoe size converter calculator. Each variable explained with a worked example.
Formulas Used
US Men's Size
us_mens = (foot_length_cm - 22) * 3 / 2.54 + 3UK Size
uk_size = (foot_length_cm - 22) * 3 / 2.54 + 2.5EU Size
eu_size = foot_length_cm * 1.5 + 2Variables
| Variable | Description | Default |
|---|---|---|
foot_length_cm | Foot Length(cm) | 27 |
How It Works
How Shoe Size Systems Work
Each sizing system has a different scale based on foot length. This calculator converts using approximate formulas.
Approximate Formulas
EU = Foot Length (cm) x 1.5 + 2
US Men's and UK are based on barleycorn increments (1/3 inch) from reference points.
Always try shoes on, as sizing varies by manufacturer.
Worked Example
Foot length of 27 cm.
- 01US Men's = (27 - 22) x 3 / 2.54 + 3 = 8.9
- 02UK = (27 - 22) x 3 / 2.54 + 2.5 = 8.4
- 03EU = 27 x 1.5 + 2 = 42.5, rounded to 43
Frequently Asked Questions
How do I measure my foot length?
Stand on a piece of paper, mark the heel and longest toe, then measure the distance in centimeters. Measure at the end of the day when feet are largest.
Do shoe sizes vary between brands?
Yes, significantly. A size 10 in one brand may fit like a 10.5 in another. Always check brand-specific size charts.
What is the difference between men's and women's sizes?
US women's sizes are typically 1.5 sizes higher than men's for the same foot length. A men's 9 is approximately a women's 10.5.
Ready to run the numbers?
Open Shoe Size Converter Calculator