How it works
Shoe sizes vary dramatically across the world because each region developed its own measurement system. The US, UK, and EU all use different numerical scales, while centimeters provide a universal physical measurement. This calculator translates between all four systems instantly, accounting for whether you're sizing men's or women's footwear—a critical distinction because the scales differ between genders.
To use it, select whether you're converting men's or women's shoes, choose which system your current size is in, enter the size, and the calculator displays the equivalent in all other systems.
The formula
Men's US = (EU size − 33.33) / 0.75 | Women's US = (EU size − 33.93) / 0.75 | UK = US − 1.5 (men's) or US − 1 (women's) | CM = (EU size − 16) / 1.27
These relationships are derived from standardized conversion tables used internationally. The EU system (Paris Points) is the baseline because it's based directly on foot length in centimeters, making it the most mathematically precise.
Worked example
Let's convert a women's US size 7 to all other systems.
Step 1: Identify the inputs
Gender: Women
Current system: US
Size: 7
Step 2: Calculate EU size
Women's EU = (US size × 0.75) + 33.93
EU = (7 × 0.75) + 33.93 = 5.25 + 33.93 = 39.18 (rounds to 39)
Step 3: Calculate UK size
UK = US − 1 (for women)
UK = 7 − 1 = 6
Step 4: Calculate foot length in centimeters
CM = (EU size − 16) / 1.27
CM = (39 − 16) / 1.27 = 23 / 1.27 = 18.1 cm
Result: A women's US 7 = UK 6 = EU 39 = 18.1 cm foot length
If you were shopping online in the UK, you'd order a size 6. If buying from a European brand, you'd look for a 39. And if a shoe description lists foot length, you'd know it should fit a foot around 18 cm long.
Common mistakes
Forgetting to select the gender: This is the most frequent error. Men's and women's scales are offset from each other—a men's US 9 and women's US 9 are completely different sizes. Always confirm your category before converting.
Rounding too early: Conversions often produce half-sizes or decimals. Don't round until you see the final result, because rounding at intermediate steps compounds the error.
Assuming all brands fit the same: Even within the same size system, brands vary. Nike might fit differently from Adidas at the same nominal size. Use this calculator as a starting point, but always check brand-specific size guides and customer reviews, which often mention fit differences.
Ignoring foot length: If you're between sizes or unsure, measuring your actual foot length in centimeters is the most reliable approach. It bypasses the ambiguity of numbered systems entirely.