Correctly Measuring For Barefoot Footwear

How to measure foot size correctly (step-by-step guide)

Knowing how to correctly measure your children's foot size is essential to ensure a barefoot shoe that fits perfectly. A common mistake is to measure the foot by sliding a finger behind the heel to check if there is any extra space. This technique is not accurate and can lead to an incorrect foot position, such as curling the toes.

Materials needed to measure at home

You don't need anything unusual to do it:

1. Paper

2. Pen

3. Tape measure

Length measurement: trace the outline and add 1 cm

This is the safest method to avoid the classic “I think it fits.” The key is to measure the foot as it is, without pushing it into the shoe or using the finger-behind-the-heel trick (which can distort the measurement).

1. Place the foot on the paper, ideally standing with weight evenly distributed.

2. Trace the outline of the foot, marking the contour clearly.

3. Mark the very back of the heel and the tip of the longest toe (it isn't always the big toe).

4. Measure in cm the distance between those two points: that is the length of the foot.

5. Add 1 cm to that measurement to get the “target” length with margin.

Example: if the foot measures 18.0 cm, the reference with margin would be 19.0 cm.

Width measurement: confirm real space at the forefoot (not just “that it fits in”)

In barefoot footwear, width matters as much as length: you can get the length right and the shoe can still fit poorly if it compresses the forefoot.

How to measure it simply:

1. With the foot resting on the paper, mark the points at the widest lateral part (metatarsals).

2. Measure that distance in cm.
   

How to interpret it when choosing footwear:

• If you tend to fit “fine in length but tight on the sides,” you need a wider last or a more anatomical toe box.
• A correct fit feels like the forefoot is supported but without lateral pressure or “pinched” toes.
  

Why correct measurement is essential in barefoot footwear

Because in barefoot footwear, the right size is the one that allows free movement inside the shoe: the foot shouldn't feel “contained” but comfortable, with room to move naturally throughout the day. If the measurement is off, the size may seem correct, but the shoe limits that freedom and the foot starts feeling tight without you noticing.

Difference between size and real space for the toes

The size is just an indicative number, but what really makes a difference is the usable interior space. Two shoes of the same size can feel very different depending on the toe-box shape, the width of the last or the instep volume. That's why measuring properly saves you from sticking with “my usual size.”

Importance of an anatomical last and a wide toe box

An anatomical last respects the real shape of the foot and lets the toes settle into their natural position. That wide “box” at the front isn't a bonus: it's what gives the foot space to move freely. In barefoot footwear, the idea is simple: the shoe accompanies the foot, it doesn't force the foot to adapt to the shape of the shoe.

Recommended growth margin in adults and children

The margin isn't “a little leftover space”: it's what prevents the foot from feeling tight when it moves. Throughout the day the foot changes (it activates, expands, may swell) and, in children, it also grows. Without that margin, a shoe may seem fine when first tried on but quickly become too short in real use, causing rubbing or a feeling of pressure.

• Children: as a practical reference, add 1 cm to the foot measurement for comfort and to avoid being short within a few weeks.
• Adults: as a practical reference, add 1 cm to the foot measurement for comfort.

Common mistakes when measuring the foot (and how to avoid them)

Measuring while seated instead of standing

The foot doesn't behave the same when seated. For a more realistic measurement, measure with the foot supported and body weight evenly distributed.

Not measuring both feet

It's normal for one foot to be slightly longer or wider. Measure both and choose based on the larger foot.

Not considering the time of day

The foot can change throughout the day. If you can, measure in the afternoon or after being active for a while.

Going only by your usual size

In barefoot footwear, the last, width and toe-box shape all matter. That's why deciding by centimetres is more reliable than by habit.

How to read a size guide correctly

Conversion between centimetres and EU size

Whenever possible, prioritise guides that show cm (recommended foot length or interior measurement). If only EU size is given, use it as a reference, but rely on the cm to get it right.

Differences between brands and lasts

The same EU size can feel different depending on:

• actual forefoot width
• toe-box shape
• instep volume

That's why not every brand “fits the same,” even when the number matches.

What to do if you're between two sizes

If you're between sizes, decide with this idea in mind: the foot should have free movement without losing support.

• If you tend to swell or take long walks, going up is usually more comfortable.
• If there's too much extra length and the heel doesn't stay stable, going down may be better.
  And always: zero lateral pressure and a feeling of freedom inside the shoe.

How to measure children's feet step by step

Recommended measurement frequency by age

In little ones, growth isn't “linear” in a way you can predict by eye: sometimes weeks pass without changes and other times they hit a growth spurt. So, as a practical guide, check the measurement every two weeks. And always keep in mind: every foot and every child is unique.

Appropriate growth margin

As a practical rule, adding 1 cm to the foot measurement usually works so it isn't tight and has room to grow.

Signs the shoe has become too small

• Red marks on toes or sides.
• They take them off, complain, or avoid walking in them
• Bruised toenails or a deformed toe box
• New trips or odd walking with that footwear

Measuring wide feet or feet with a high instep

How to tell if you need a Wide last

Typical signs:

• fine in length, but pressure at the forefoot
• lateral marks when removing the shoe
• a feeling of “tightness” at the metatarsals
• the toe box deforms outwards

Correct fit without lateral compression

A correct fit feels like this:

• stable heel (not slipping)
• comfortable instep (not pinching)
• free forefoot (no lateral pressure)
• an overall feeling of free movement

Frequently asked questions about how to measure foot size

How often should I measure my foot?

• Adults: when changing brand/model or noticing changes (more activity, discomfort, etc.).
• Children: according to age (above) and always if rubbing or complaints appear.

Is measuring with a mobile app reliable?

It can give you an idea, but to fine-tune size and last, the paper-and-cm method is usually more consistent.

Does foot size change over the years?

It can change: the foot may widen or vary with habits, activity, pregnancy or injuries. That's why measuring in cm from time to time helps.

Does sock type affect measurement?

Yes. If you're going to wear thick socks, measure with that sock on or take it into account when choosing the margin. For sandals or barefoot use, measure without socks.

Instagram Video

Here's the video so the measuring process is even easier for you.

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A post shared by Alejandro Martínez - Pediatric podiatry 🦶 (@lejancitos)