US kids shoe size to cm
Choose a US size to see the foot length it fits, then compare it with your child’s measurement.
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How to use it
- Enter us size.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
US child size = 3 × last length (in) − 11.75; Y sizes continue the same scale after 13.5C. Last length = foot length + 2/3 in. Combined: foot length (in) = (US + 9.75) ÷ 3.
Example
Inputs: US size = 4C. Result: Approximate foot length: 11.6 cm; Foot length in inches: 4.58 in; Last length: 13.34 cm.
Limits and caveats
- The last is taken as 2/3 in (about 17 mm) longer than the foot; some European makers add only 13 mm.
- Brands differ by half a size to a full size, so check the brand chart before you buy.
Questions about this tool
How much longer is half a US size?
Half a size is 1/6 inch, about 4.23 mm.
What is the difference between foot and last length?
The last is the inside shape of the shoe, about 17 mm longer than the foot to leave toe room.
My child’s foot is 12 cm, which size fits?
Pick the size whose foot length equals or slightly exceeds the measurement, around 4.5C here.