A 150 mm foot marks the small end of this range, a length most children reach around age three; Austrian tracking shows the foot still adding close to 1 mm a month at this stage.
CM to US conversion
Centimetres convert to US kids' sizes by subtracting about 7 until the US scale resets, after which the same length reads roughly 20 less: 18 cm is US 11 but 21 cm, past the reset, is US 1. The foot measurement is the only figure that keeps rising cleanly through the jump. Sizing a growing child by the millimetre length, with room to spare, sidesteps the US number that doubles back mid-scale.
At this size, CM to US
One size up from 15 cm, US moves 0.5 to US 8.5 while the metric length rises 0.5 to 15.5 cm. Both 15 cm and US 8 are whole numbers here, so nothing rounds. For 15 cm, the US column here runs US 8, US 8.5, US 9, stepping a half size at a time.
Foot length vs shoe length
A CM shoe size is your measured foot length, not the space inside the shoe.
Brands add 0.5 to 1.0 cm of toe room so your toes clear the front. Japanese cm
labels already include about 1 cm of it, so a JP 24.0 measures near 25 cm
inside; an EU number instead describes the last. That built-in gap is why
conversion tables disagree.
Why one foot length gives many sizes
Size Chart CM EU US UK 15 24 8 7 15.5 25 8.5 7.5 16 26 9 8 16.5 27 9.5 8.5
Frequently Asked Questions Does 15 cm round up or down in US? With the foot still growing, round to the larger size: the extra millimetres become fit within weeks. Aim for 12 to 17 mm past the longest toe when the shoe is on.
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Note Kids sizes transition to adult sizes around EU 38 / US 5 Children's feet grow rapidly - remeasure every 3-4 months Allow 10-15mm growing room when fitting Shoe sizes can vary by brand and style See a number that looks off? Report an error on this page.