Size Guide kids

We have made changes in our size guide, if you have bought KOOPS before, re-chek your size before buying to avoid mistakes. KAI has same sizing as RAFI. 

22	5C	4.5	12,9	13,6	6,3
23	6C	5.5	13,6	14,3	6,4
24	7C	6.5	14,3	14,9	6,6
EU	US	UK	MIN LENGHT	MAX LENGHT	INSOLE WIDTH
25	8C	7.5	14,9	15,6	6,7
26	9C	8.5	15,6	16,3	6,9
27	10C	9.5	16,3	16,9	7,0
28	11C	10.5	16,9	17,6	7,1
29	11.5C	11	17,6	18,3	7,3
30	12C	11.5	18,3	18,9	7,5
31	13C	12.5	18,9	19,6	7,6
32	1Y	13	19,6	20,3	7,8
33	2Y	1	20,3	20,9	7,9
34	3Y	2	20,9	21,5	8,1
35	4Y	2.5	21,5	22,2	8,2

All sizes in centimeters

MIN LENGHT - Minimum length for which that size is suitable for purchase. If your measurement is shorter, you should buy a smaller size.

MAX LENGHT -Maximum length for which that size is suitable for purchase. If your measurement is longer, you should buy a larger size.

INSOLE WIDTH -Maximum width that should not be exceeded for that size.

Why barefoot sizing differs from conventional sizing

The numbering (36, 37, 24, 25) is the same across any shoe. What changes is the last: the shape the shoe is built around on the inside.

Conventional footwear tends to use a narrow last, especially around the toes, because it prioritises a particular silhouette over the actual shape of the foot. Barefoot footwear does the opposite: a good barefoot shoe is free from toxic components, has no anatomical insoles or rigid reinforcements, and offers a wider toe box that respects the foot’s natural shape.

What does this mean in practice? Two shoes with the same size number, say, a 28, can feel completely different on your child’s foot depending on whether they’re barefoot or conventional. That’s why measuring your child’s foot at home before buying is far more reliable than relying on their usual size.

Size conversion chart by age

This chart is a guide only: every foot grows at its own pace, so an actual measurement always takes priority over age.

How to measure your child’s foot step by step

You don’t need any special equipment, a sheet of paper, a pencil and a ruler will do.

First, place a sheet of paper on the floor, against a wall or any firm, straight edge.

Next, ask your child to stand on the paper with their heel touching the wall or the straight edge. It’s best to measure feet at the end of the day, when they tend to be slightly more swollen, that way you’ll be sure the shoe is comfortable at any time of day.

Then, mark with the pencil the furthest point from the heel, usually the tip of the longest toe (which isn’t always the big toe).

Measure the distance between the heel mark and the toe mark with the ruler. That’s your child’s actual foot length.

Finally, repeat with the other foot: it’s common for one foot to be slightly larger than the other. If there’s a difference, always use the larger foot as your reference.

How much space to leave in the barefoot toe box

This is probably where most parents get it wrong, in both directions.

The recommended difference between foot length and shoe length is around 15mm, measured from the longest toe to the back of the heel. In other words: not a shoe that matches the foot exactly (which would become too tight as soon as the foot swells or grows a few millimetres), and not a shoe two sizes too big to make it last, which would let the foot slide around inside, drag, and lose stability while walking.

A simple way to check, in-store or at home: with the shoe on, there should be room for your child to move their toes freely, but the heel shouldn’t slide forward and back while walking.

When to size up: signs to watch for

Children’s feet grow in spurts, not in a straight line, so it’s worth watching for signs, not just counting months since the last pair.

• Feet can grow up to 8mm per quarter, so checking every 8-12 weeks is the safest approach, especially under age 4.
• Red marks on toes or the top of the foot when removing the shoe, even if your child doesn’t complain.
• Your child keeps taking the shoe off, or says it bothers them with no obvious reason.
• Visually, toes reach the front of the shoe when your child is standing with their full weight on it.
• Seasonal changes: thicker winter socks or tights can turn a shoe that fit perfectly in summer into one that’s now too tight.

Common sizing mistakes with children’s footwear

• Going by age alone. Charts are a guide, not a rule. Two children the same age can have feet more than a full size apart.
• Measuring while seated. The foot widens and lengthens slightly when bearing weight. Measuring only while seated gives a smaller-than-real size.
• Buying room to grow. As we’ve seen, the ideal margin is around 15mm, not several centimetres. An oversized shoe doesn’t last longer: it just means the foot works poorly while it’s too big.
• Not checking both feet. Assuming both feet are identical can mean a shoe fits perfectly on one foot and is slightly tight on the other, and over time, that shows too.
• Ignoring width. Focusing only on length and forgetting the toe box. In barefoot shoes, a narrow toe box on a shoe that’s the right size is still a shoe that doesn’t respect the foot.

FAQs about kids’ shoe sizing

Is barefoot sizing the same as my child’s usual size?

Not always. The barefoot last tends to be wider, so the same number can feel different. The most reliable approach is to measure the foot at home and compare it with the specific model’s conversion chart.

Should I buy a bigger size so it lasts longer?

It’s not recommended. The ideal margin is around 15mm, not several centimetres. An oversized shoe means the foot works worse while it’s too loose.

How often should I measure my child’s foot?

Every 8-12 weeks is a good rule of thumb, especially under age 4, since feet can grow up to 8mm per quarter.

What if one foot is bigger than the other?

That’s very common. Always use the larger foot as your reference when choosing a size.

Is it better to measure in the morning or the evening?

In the evening or at the end of the day, since the foot tends to be slightly more swollen, and that measurement better reflects how the shoe will feel during daily wear.