The Complete Guide to Measuring Children’s Feet: Tips and Mistakes to Avoid

The right footwear is key to healthy development of children’s feet. But how do you choose the right size? First, you need to measure your child’s feet accurately.

In this comprehensive naBOSo guide, we’ll walk you through the entire process of measuring children’s feet. We’ll reveal the most common mistakes parents make, explain why growing room matters, and share practical tips for accurate measuring.

Whether you’re a seasoned parent or choosing shoes for your child for the first time, this article will help you make sure your little one always walks comfortably and healthily.

Why accurate measuring matters

Did you know that ill-fitting shoes can negatively affect the development of children’s feet and even the way they walk?

Shoes that are too small pinch, deform the toes and prevent healthy growth. On the other hand, shoes that are too big can cause blisters, pressure points and tripping.

The solution is simple: measure your child’s feet regularly—for younger children, ideally every 2–3 months. When choosing shoes, follow the current measurements of the foot rather than your child’s age or the size of other shoes, because sizing can vary between manufacturers. It’s also important not to buy shoes “for later”, because children’s feet grow very quickly and their size can jump in a short space of time.

The basics of measuring children’s feet

With these four essentials, you’ll always have a clear idea of your child’s current foot size:

Measure regularly every 2–3 months, ideally in the afternoon, when the foot is at its largest.
Always measure both feet—they can differ by several millimetres.
Prepare a good measuring tool (ideally PLUS12) and paper with a pencil to record the results.
Measure your child barefoot and standing on a hard floor, so the foot can spread naturally.

naBOSo tip: Measuring by tracing around the foot or against a wall can be very inaccurate for children, so we don’t recommend it.

Step-by-step measuring method

Accurately measuring foot length and width is the foundation for choosing shoes that fit properly and won’t restrict healthy development of children’s feet. At naBOSo, we recommend all parents get the PLUS12 measuring tool, which lets you measure children’s feet accurately and easily—and also check the internal dimensions of shoes straight away. Considering how often you’ll use it over the coming years and how much stress it can save you, it’s an investment that’s well worth it.

It’s best to measure length with the PLUS12 tool

Your child stands barefoot on the tool, with the heel touching the back wall and the longest toe in the red tip.
Your child needs to stand upright, look straight ahead and keep their weight evenly on both feet for an accurate measurement.
Measure both feet—and for greater accuracy, repeat the measurement once more.
Important: the PLUS12 measuring tool measures the foot including a 12 mm allowance—so the result is an approximate recommended shoe size for that foot.

naBOSo tip: If you want the exact foot measurement (without allowance), subtract 12 mm from the value shown on the PLUS12 tool.

No PLUS12 tool to hand? A box will do

This method is a more accurate alternative to tracing around the foot, where a pencil held at an angle can add or subtract several millimetres. So how do you do it?

Gently press the heel and the big-toe edge of the foot against the side of the box.
Your child needs to stand upright, look straight ahead and keep their weight evenly on both feet for an accurate measurement.
With the pencil held vertically, make a mark at the longest toe and on the little-toe side.
Use a ruler to measure the length from the longest toe to the centre of the heel, and the width.
Measure both feet—and for greater accuracy, repeat the measurement once more.
Add a growing allowance to the measured values: 12 mm to the length and 2–7 mm to the width, and you’ll have the approximate internal shoe size you’re looking for.

Measure width with callipers or a ruler

The right shoe width is just as important as length. Shoes that are too narrow deform the toes; shoes that are too wide can cause pressure points.

Always measure the width across the toe joints, even if it isn’t always the widest part of the foot—some children have wider toes.
Add an allowance of 2–7 mm to the measured value.
Tracing is just as misleading for width as it is for length.

Important! Measuring width in the toe area makes sense if you want conventional shoes—so children have a chance of fitting into those narrower toe boxes. With barefoot footwear, a wide toe box is the standard, so we always measure width across the joints—both on the feet and inside the shoes.

The 5 most common mistakes when measuring feet

Does measuring feel too complicated? Don’t worry—you’ve got this. Choose a moment when your child is calm, set aside enough time, and avoid these common mistakes:

Leaving too long between measurements. For the very youngest children, measure feet ideally every month; for nursery-age children, checking once every two months is usually enough; and for school-age children, once a quarter.
Measuring against a wall instead of in a box. The heel can get pushed too firmly into the wall, which shortens the measured length.
Measuring while sitting or lying down instead of standing. The foot isn’t fully weight-bearing, which skews the result.
Tracing the foot with a pencil on paper. The pencil often drifts away from the foot, which can add as much as 5 mm. Parents sometimes think that measuring “a bit more” is a bonus for the future—but the opposite is true.
Measuring at different times of day. Feet get more blood flow during the day and increase in volume. That’s why it’s best to measure length and width in the afternoon.

Growing allowance and how to interpret your measurements

You’ve measured foot length and width—so what do you do with the numbers now? How do you choose the right shoe size?

The key is the concept of a growing allowance—extra space inside the shoe that your child needs for comfort and healthy growth. The size of the allowance is individual for each child. Some children can walk comfortably with a 20 mm allowance, while others struggle even with just (the generally recommended) 12 mm. It also varies by shoe type. As a general guide, you can follow the recommendations below:

Crawling babies can have an allowance of up to 15 mm, because when crawling the extra space sits behind the heel. They also grow very quickly.
For children up to 3 years old, ideally add 8–12 mm to the foot length.
For children aged 3–6, add 10–12 mm.
For children over 6, allow 8–10 mm.

The right allowance ensures the shoe doesn’t pinch or squeeze anywhere, while still giving enough room for natural toe movement when walking.

Example: A three-year-old child’s measured foot length is 138 mm. The ideal internal shoe length is therefore 138 + 12 = 150 mm.

A growing allowance isn’t an unnecessary luxury—it’s essential for healthy development of children’s feet.

Shoes need to fit properly above all

Measurements such as instep height, ankle width or heel width also matter, but measuring them isn’t necessary. It’s enough to know whether your child has a chubbier or slimmer foot, and a higher or lower instep. Not sure? Visit one of our shops and our barefoot advisors will measure your child’s feet professionally and help identify their foot type too. But if you don’t have access to a knowledgeable specialist, how can you tell whether shoes “fit”?

Check the space behind the heel—there should be no visible empty area on the insole: not behind the heel and not next to it. In loosened shoes, a finger will of course fit next to the heel/ankle, but it shouldn’t fit next to the heel on the insole.
For width, the shoe should feel uncreased and roomy across the joints, with soft leather that isn’t stretched tight.
And what about the instep? With bought shoes, it’s enough to slide 1–2 fingers under the tongue of the shoe while it’s on. If they fit comfortably, the shoe can flex in the tongue area and everything works as it should.

Watching your child is key

Although factors like allowance, width and overall fit are important, the most important thing when choosing children’s shoes is to watch how your child walks. The right shoe shouldn’t change your child’s natural walking pattern. Pay attention to how your little one walks completely barefoot—once they put shoes on, their gait and overall body movement should look similar. Some children cope well with a larger allowance; others struggle even with a smaller one.

Try shoes on in the afternoon, when your child’s foot is at its “largest”.
Let your child run a little in the shoes, jump, and stop.
Check the shoe’s flexibility—your child should be able to bend the shoe easily when walking. In general, the younger the child, the softer the shoe needs to be so they can “break it in” with their steps.

If possible, let your child try shoes on in a specialist shop, where staff can give you informed advice. They’ll not only measure the foot professionally, but also help you choose the right type of footwear.

Choosing the right children’s footwear

Barefoot shoes shouldn’t restrict the foot in any way when walking or interfere with its natural development. Shoes should be, above all, lightweight and flexible, with a wide toe box and a flat, unshaped sole. And that’s exactly what you’ll find with us. For the tiniest little ones, choose soft baby shoes or pre-walkers, which are very soft and don’t stiffen the ankles. For older children, you’ll need proper trainers, and for cooler days, durable all-season shoes. And when frost arrives, it’s time for insulated winter boots. For heavy rain or puddles, pop your child in barefoot wellies. Got a school-age child at home? Don’t forget comfortable indoor shoes.

If you’re not sure what to choose, drop into one of our three shops in Prague and we’ll be happy to help. You’ll find more tips in these articles:

In conclusion…

Measuring children’s feet correctly is a crucial step towards supporting healthy foot development. With our detailed guide, you now have everything you need to measure your child’s feet accurately and choose the ideal shoes. Remember: regular re-measuring is essential, because children’s feet grow quickly.