Baby & Toddler Shoe Size Calculator
Convert a measured foot length to baby and toddler shoe sizes — UK, US and EU — with growing room and how soon to measure again.
How it works
EU = (foot + room) ÷ 0.667 cm; UK child = (foot + room) ÷ 0.847 cm − 12; US child ≈ UK + 1
Children’s sizes follow the shoemaker’s barleycorn (⅓ inch) in the UK/US and the Paris point (⅔ cm) in Europe, so a size is only a length band. Measure the foot standing, from the heel to the longest toe, and add 1–1.5 cm of growing room — enough for a thumb-width at the toe. Brands vary by half a size, so the insole length in centimetres is the number worth checking on the box or the brand’s chart.
Worked example
A 12.5 cm foot plus 1 cm room = 13.5 cm: EU 21, UK 4½, US 5½ — a typical 18-month-old.
Frequently asked questions
Do babies need shoes before walking?
No — barefoot or soft booties are best for development. First proper shoes come when they walk confidently outdoors.
How much growing room?
1 cm (about a thumb) is standard; up to 1.5 cm for fast growers, never so much that the heel slips.
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This calculator is for educational purposes. Double-check important results before acting on them.