Shoe Size Converter: US, UK, EU & Foot Length
Short answer
This shoe size converter estimates equivalent footwear sizes across US, UK, and European (EU) measurement systems, alongside estimated foot length. For example, a US Men's size 9 converts directly to an EU size 41.5, a UK size 8, and an approximate foot length of 26.2 cm (10.33 inches).
Formula
Foot Length (in) = (US Size + C) / 3 | Foot Length (cm) = Foot Length (in) × 2.54 | UK Size = (3 × Foot Length (in)) - 23 | EU Size ≈ 1.5 × (Foot Length (cm) + 1.5)
US Size is the numerical size entered for footwear; C is an offset constant equal to 22 for US Men and 21 for US Women; Foot Length (in) represents the estimated anatomical length of the foot in inches based on traditional barleycorn units (1/3 inch per full size); Foot Length (cm) is the metric equivalent using 1 inch = 2.54 cm; UK Size uses the traditional British scale starting one size lower than standard US Men's sizing; EU Size uses the Paris Point system, where each Paris Point corresponds to 2/3 cm (hence multiplying by 1.5), adding an industry allowance of approximately 1.5 cm for toe box clearance.
Worked example
- Size system
- men
- US size
- 9
- EU size: 41.5
- UK size: 8
- Foot length: 26.2 cm (10.33 in)
- Note: Sizes vary by brand; check the brand's chart
What the Shoe Size Converter Calculates
International footwear sizing uses distinct historical standards that do not translate on a simple 1:1 basis. The Shoe Size Converter translates standard adult US footwear sizes into their corresponding European (EU) and British (UK) designations while calculating the estimated anatomical foot length in both centimeters and inches.
This tool is designed for:
- Online shoppers ordering imported footwear from international retailers.
- Travelers purchasing shoes abroad.
- Runners and athletes needing to align foot length measurements in centimeters with standard retail box sizes.
- Individuals looking to understand the core sizing differences between US Men's and Women's footwear scales.
Traditional English and American shoe sizing systems trace their origin to the "barleycorn"—an archaic unit equal to 1/3 of an inch. Each full size step represents an increase of one barleycorn in last length. In contrast, European sizing relies on the "Paris Point," which measures two-thirds of a centimeter (6.67 mm). This calculator applies these mathematical baselines to translate sizes smoothly across systems.
Step-by-Step Worked Example
To see how the mathematical conversion functions, consider a standard user input of an adult US Men's size 9.
1. Calculate Estimated Foot Length
In the traditional US Men's scale, the formula for foot length in inches is: $$\text{Length (in)} = \frac{\text{US Size} + 22}{3}$$
Substituting the input: $$\text{Length (in)} = \frac{9 + 22}{3} = \frac{31}{3} \approx 10.33\text{ inches}$$
Converting inches to centimeters ($1\text{ inch} = 2.54\text{ cm}$): $$\text{Length (cm)} = 10.3333 \times 2.54 \approx 26.24\text{ cm} \rightarrow 26.2\text{ cm}$$
2. Calculate the UK Size
In the British sizing system, adult sizes start one increment below the standard US Men's sizing scale: $$\text{UK Size} = 3 \times \text{Length (in)} - 23$$ $$\text{UK Size} = (3 \times 10.3333) - 23 = 31 - 23 = 8.0$$
Thus, a US Men's 9 corresponds to a UK size 8.
3. Calculate the European (EU) Size
The European scale uses the Paris Point ($2/3\text{ cm}$). A functional allowance of approximately $1.5\text{ cm}$ is added to anatomical foot length to ensure adequate toe room: $$\text{EU Raw} = 1.5 \times (\text{Length (cm)} + 1.5)$$ $$\text{EU Raw} = 1.5 \times (26.244 + 1.5) = 1.5 \times 27.744 = 41.616$$
Rounding to the nearest standard half-size: $$\text{EU Size} = 41.5$$
Summary of Results for US Men's 9:
- EU Size: 41.5
- UK Size: 8
- Foot Length: 26.2 cm (10.33 in)
How to Read the Results and Sizing Benchmarks
When evaluating converted shoe sizes, remember that conversion tables provide a central reference point rather than an absolute rule.
| Measurement | Typical US Men's Equivalent | Typical US Women's Equivalent | Metric Foot Length | | :--- | :--- | :--- | :--- | | Small / Petite | US 6 – 7 (EU 38.5 – 39.5) | US 5 – 6.5 (EU 35.5 – 37) | ~22.0 – 24.5 cm | | Average Adult | US 8.5 – 10.5 (EU 41 – 43.5) | US 7.5 – 9.5 (EU 38 – 40) | ~25.0 – 27.5 cm | | Large / Tall | US 11 – 13 (EU 44 – 46.5) | US 10.5 – 12 (EU 41.5 – 43) | ~28.0 – 29.5 cm |
- Centimeter (CM) / Mondopoint Standard: The foot length in centimeters is the most consistent metric globally. If an international brand lists "CM" or "JP" sizing, that number denotes actual length inside the shoe or recommended foot length, eliminating the confusion of regional sizing labels.
- US Men vs. Women: A standard US Women's size is roughly 1.0 to 1.5 numerical units larger than a US Men's size for the same foot length. For example, an adult foot measuring 26.2 cm corresponds to a US Men's 9 or a US Women's 10.
Practical Tips for Getting the Correct Fit
- Prioritize Centimeters Over Regional Numbers: When purchasing athletic or performance footwear from global brands, compare your bare foot length directly to the brand's metric (cm) chart rather than relying solely on US-to-EU conversions.
- Account for Socks and Orthotics: If you plan to wear thick wool socks, compression sleeves, or custom orthotic insoles, measure your foot with those items on or size up by half a size.
- Assess the Toe Box Shape: Pointed dress shoes require more clearance at the front than rounded or anatomical toe-box shoes. If you have wider forefeet or long second toes, rounding up to the nearest half or full EU size prevents pinching.
When Not to Rely on Standard Formulas
While these formulas represent standard manufacturing conventions, they should not be your sole guide in specific circumstances:
- Technical Footwear: Ski boots, rock-climbing shoes, and cycling cleats prioritize extreme foot containment or rigid structural contact. They follow specialized sizing scales (such as strict Mondopoint without toe clearance) that standard formulas will overestimate.
- Extreme Width Profiles: Standard formulas assume a normal proportional width (D for men, B for women). If you have exceptionally narrow (A/B) or wide (E/EE/4E) feet, changing the shoe length to compensate for width often leads to heel slippage or arch misalignment.
- Handcrafted and Vintage Shoes: Bespoke leather footwear and heritage dress shoes often rely on proprietary historical lasts that run significantly larger or smaller than modern athletic sneakers.
Comparison
| Scenario | Input | Result |
|---|---|---|
| Lower input | US size: 7.2 | EU size: 39.5 |
| Base example | US size: 9 | EU size: 41.5 |
| Higher input | US size: 10.8 | EU size: 44 |
Common mistakes
- Assuming US men's and women's sizes are identical; a women's size is typically 1 to 1.5 sizes larger in numerical value for the exact same foot length.
- Neglecting foot width (such as Narrow B, Standard D, or Wide EE), which significantly alters fit regardless of correct length conversion.
- Measuring foot length while seated, which reduces foot elongation and arch flattening under natural body weight.
- Treating European (EU) sizes as perfectly linear across all fashion labels, as European lasts vary widely between Italian, German, and French manufacturers.
- Failing to account for activity-specific toe allowance, such as the extra half-inch needed in hiking boots or marathon running shoes.
Checklist
- Measure your feet at the end of the day when they are slightly swollen to their largest natural volume.
- Stand upright on a firm, flat surface against a wall while taking foot length measurements.
- Wear the specific type of socks or hosiery you plan to wear with the shoes.
- Measure both feet from the back of the heel to the tip of the longest toe in millimeters or inches.
- Base your size conversion on the larger of your two feet if there is an anatomical difference.
- Check brand-specific sizing guides for running, climbing, or cycling shoes, which often deviate from standard conversions.
Calculators Percentage Editorial Team
Calculator guides from the Calculators Percentage team. These introductory examples are educational, not professional advice.
Last reviewed:
Shoe size conversion formulas provide standard mathematical approximations. Because shoe lasts, internal padding, and widths vary significantly between manufacturers, always verify fit using the specific brand's sizing chart.