Kids' Shoe Size Chart: From Toddler to Big Kid to Adult
Children's shoe sizing is its own system — separate from adult sizing, divided into multiple age-based categories and often baffling to navigate. A "US 5" in toddler sizing is not the same foot as a "US 5" in big kids' sizing, and neither is the same as a US 5 in adult women's. If you've ever looked at a shoe size chart for kids and found it incomprehensible, this guide will clear it up.
How Kids' Shoe Sizing Is Structured in the US
US children's shoe sizing uses three distinct categories:
- Infant / Toddler (C sizes): Typically marked with a "C" (e.g., 3C, 4C, 5C) and covering very young children from newborn up to around age 4. The smallest sizes start at 0C for newborns and run up to around 10C.
- Little Kid (K or no suffix): Generally sizes 10.5 to 3, covering ages 4 to 7 roughly. Sometimes written as "10.5K" or simply "10.5."
- Big Kid (Y sizes): Marked with a "Y" (e.g., 3.5Y, 4Y, 5Y, 6Y, 7Y) and covering ages 7 to about 12–14. Big Kid sizing runs from roughly 3.5Y to 7Y, after which children typically graduate to adult sizing.
The C/K/Y distinction is US-specific. UK and EU kids' sizing runs as a single continuous scale without these category breaks.
Toddler Shoe Size Chart (US, UK, EU, CM)
- US 4C → UK 3.5 → EU 19.5 → 11 cm
- US 5C → UK 4.5 → EU 21 → 12 cm
- US 6C → UK 5.5 → EU 22 → 13 cm
- US 7C → UK 6.5 → EU 23 → 14 cm
- US 8C → UK 7.5 → EU 25 → 15 cm
- US 9C → UK 8.5 → EU 26 → 16 cm
- US 10C → UK 9.5 → EU 27 → 16.5 cm
Little Kid and Big Kid Size Chart (US, UK, EU, CM)
- US 10.5K → UK 9.5 → EU 27.5 → 17 cm
- US 11K → UK 10 → EU 28 → 17.5 cm
- US 12K → UK 11 → EU 30 → 18.5 cm
- US 13K → UK 12 → EU 31.5 → 19.5 cm
- US 1Y → UK 13 → EU 32 → 20 cm
- US 2Y → UK 1 → EU 33 → 21 cm
- US 3Y → UK 2 → EU 35 → 22 cm
- US 3.5Y → UK 2.5 → EU 35.5 → 22.5 cm
- US 4Y → UK 3 → EU 36 → 23 cm
- US 4.5Y → UK 3.5 → EU 36.5 → 23.5 cm
- US 5Y → UK 4 → EU 37.5 → 24 cm
- US 5.5Y → UK 4.5 → EU 38 → 24.5 cm
- US 6Y → UK 5 → EU 38.5 → 24.5 cm
- US 6.5Y → UK 5.5 → EU 39 → 25 cm
- US 7Y → UK 6 → EU 40 → 25.5 cm
When Do Kids Graduate to Adult Shoe Sizes?
Most children move into adult sizing somewhere around US 7Y or US 7.5Y, which corresponds to approximately EU 40 and a foot length of 25–25.5cm. At this point, the kids' size range simply ends and you move into the adult scale.
For girls, a US 7Y big kids' size is approximately equivalent to a US women's 8.5. The transition is often made slightly earlier for girls because women's sizes start at a smaller foot length than men's. For boys, a US 7Y is roughly a men's US 7 — nearly the same number, but now on the adult scale.
There's no exact age at which this happens — it depends entirely on the child's foot. Some kids hit adult sizes at age 11; others are in big kids' sizes at 14. Let the foot length determine the category, not the age.
Kids' Shoes vs Adult Shoes: What's Actually Different?
Beyond the numbering, there are real construction differences between children's and adult shoes. Kids' shoes typically have:
- More flexibility in the sole to accommodate the natural development of foot muscles and arch
- Wider toe boxes relative to length, to account for the wider proportions of children's feet
- Lighter construction, since children's feet tire more easily under weight
- Simpler fastening systems (Velcro, slip-on) in smaller sizes that children can manage independently
Importantly, adult sneakers in the same size as a big kids' shoe will often fit slightly differently — the last shape is different, the proportions of the upper vary and the sole construction is built for adult weight and gait. For a teenager in the US 7Y/Men's 7 transition zone, it's worth trying both to see which fits better for their specific foot shape.
How to Measure a Child's Foot
Children's feet are harder to measure accurately than adults' because kids tend to scrunch their toes or shift their weight during the process. The easiest approach: have the child stand on a piece of paper on a hard floor with someone else tracing while they're distracted. Measure from the back of the heel to the tip of the longest toe with a ruler. Match that CM measurement against the size chart above.
Always leave about 1cm of growing room in a child's shoe. A shoe that fits perfectly today will be too small in three months. For very young children growing quickly, some parents leave slightly more room — 1.5cm — particularly if the next size up has good ankle and heel support.
Use the kids' tab on our converter for instant size conversions across US, UK, EU and CM — covering toddler, little kid and big kid ranges.
Open the kids' size converter →Kids' Shoe Sizing in the UK and EU
In the UK, children's sizes run from UK 0 for newborns upward and continue as a single unbroken scale into adult sizes (unlike the US system's C/K/Y categories). UK sizes 0–13 typically cover children's feet, then the numbering restarts at UK 1 (adult) — which is a different size from UK 1 in the children's scale.
European sizing for children follows the same Paris Point system as adult EU sizing, so EU 22 is simply two-thirds of a centimetre smaller than EU 23. This makes EU-to-CM conversion particularly clean for kids, since the scale is continuous.
Disclaimer: Kids' shoe size charts are a guide. Children's foot proportions vary significantly between individuals. Measuring your child's foot is always preferable to estimating by age.