If you've ever tried to buy Primark kids' shoes online — or popped in without your child to grab a quick pair — you'll know the problem immediately. Primark's shoe pages show a UK size. That's it. No centimetres, no foot length in inches, no EU equivalent on the product page. Just a number that means nothing on its own unless you already know UK shoe sizing by heart.
It's an odd gap for a brand that sells tens of millions of pairs of children's shoes every year. The most charitable explanation is that Primark's model was built around in-store shopping — you bring the child, you try the shoe on. But with Click & Collect and online browsing now a normal part of how British parents shop Primark, the missing centimetre column is a genuine friction point.
This guide gives you what Primark doesn't: the full UK → EU → cm conversion for kids' shoe sizes, from toddler through to junior, so you can shop confidently from a foot measurement alone. It also covers how to measure your child's foot correctly and what to do when they're between sizes.
Primark Kids Shoe Sizes: UK to EU to cm
Important note: Primark does not publish foot length measurements in centimetres for their shoe range. The cm values in this table are standard estimates based on the widely used UK/EU shoe size conversion, and are consistent with industry sizing conventions. Individual shoes may vary slightly — always add around 1 cm (roughly a thumb's width) of growing room when buying for a child.
| UK Size | EU Size | Foot length (cm) * | Foot length (in) * | Approx. age |
|---|---|---|---|---|
| 3 | 19 | 11.5 cm | 4 1/2" | 12–18 months |
| 4 | 20 | 12.5 cm | 5" | 18–24 months |
| 5 | 21 | 13.0 cm | 5 1/8" | 2 years |
| 6 | 22–23 | 13.5 cm | 5 3/8" | 2–3 years |
| 7 | 23–24 | 14.5 cm | 5 3/4" | 3 years |
| 8 | 25–26 | 15.5 cm | 6 1/8" | 3–4 years |
| 9 | 26–27 | 16.0 cm | 6 1/4" | 4–5 years |
| 10 | 27–28 | 16.5 cm | 6 1/2" | 5 years |
| 11 | 29 | 17.5 cm | 6 7/8" | 5–6 years |
| 12 | 30–31 | 18.5 cm | 7 1/4" | 6–7 years |
| 13 | 31–32 | 19.5 cm | 7 5/8" | 7–8 years |
| 1 (junior) | 33 | 20.5 cm | 8 1/8" | 8–9 years |
| 2 (junior) | 34 | 21.0 cm | 8 1/4" | 9–10 years |
| 3 (junior) | 35–36 | 22.0 cm | 8 5/8" | 10–11 years |
| 4 (junior) | 36–37 | 23.0 cm | 9" | 11–12 years |
| 5 (junior) | 37–38 | 23.5 cm | 9 1/4" | 12–13 years |
* Foot length values are standard estimates based on UK/EU shoe size conventions. Primark does not publish official cm measurements. Always allow approximately 1 cm of growing room when selecting a size.
Why Primark Doesn't List Shoe Sizes in Centimetres
The short answer is that Primark's retail model was built entirely around in-store shopping. You bring the child, you try the shoe on, you buy it. For decades that worked fine, and there was no pressing need to publish foot length data on a chart nobody would look at in a physical store.
UK shoe sizing also has a long history of not using metric measurements — it predates the metric system entirely. Unlike EU shoe sizes, which are loosely based on the Paris point (approximately ⅔ of a centimetre per size), UK sizes are a purely conventional numbering system with no direct physical unit. Most British retailers that do publish cm measurements are doing so as an added service on top of the UK system, not because the system inherently supports it.
With online browsing and Click & Collect now a normal part of how parents shop Primark — and with many parents outside the UK shopping their ranges via third-party resellers — the missing centimetre column has become a genuine gap. Until Primark updates their size guides, the conversion table above is the most practical workaround.
How to Measure Your Child's Foot in cm
Measuring your child's foot takes about two minutes and eliminates almost all sizing guesswork. The foot length in cm is the only measurement that maps cleanly across all shoe size systems.
Step-by-step:
- 1Place a sheet of plain A4 paper on a hard floor (not carpet — it compresses). Have your child stand on it with their full weight down.
- 2Use a pencil to mark the very tip of the longest toe and the back of the heel. Do both feet — most people's feet differ slightly.
- 3Measure the distance between the two marks with a ruler. This is the foot length in cm.
- 4Use the larger of the two feet. Add approximately 1 cm for growing room before looking up the size in the table above.
Measure in the afternoon if possible. Feet swell slightly throughout the day — measuring in the morning can produce a reading up to 5 mm shorter than the evening. Sizing to the afternoon measurement means the shoe fits all day, not just at 8am.
What to Do When Your Child Is Between Sizes
If your child's foot measurement falls between two sizes in the table, the right call depends on the type of shoe and how much room is already in the design.
- Trainers and casual shoes: Size up. These styles typically have a soft, flexible toe box that accommodates a little extra length without the shoe slipping at the heel.
- School shoes and boots: Try both sizes if possible. Structured shoes with a firm heel counter fit differently — too large means heel slip and blisters, not just a loose toe.
- Sandals and flip-flops: Primark's sandal sizing tends to run close to foot length with minimal extra room — sizing up by one is usually the right move, especially for wide feet.
- Wellies and slippers: These are worn with thick socks — always size up one, or even two for wellies that need to go on over wellies socks.
The UK Size 13 → Junior 1 Reset: What It Means
One of the most consistently confusing things about UK children's shoe sizing — and Primark is no exception — is that the numbering resets after size 13. A child who outgrows a UK 13 moves to a UK junior 1, which is larger than a UK 13 despite the smaller number.
UK 13 ≈ 19.5 cm foot. UK Junior 1 ≈ 20.5 cm foot. Junior 1 is one size larger than 13, not smaller. The numbering restarts — it does not go backwards.
The practical implication: if Primark lists a shoe as available in sizes “10–13, 1–5” that is a continuous range from approximately 16.5 cm (UK 10) up to 23.5 cm (UK junior 5). The gap between 13 and 1 is a single size step of around 1 cm, the same as any other step in the range.
Frequently Asked Questions
Does Primark publish kids' shoe sizes in cm?
No — Primark lists kids' shoe sizes in UK sizes only. The centimetre values in this guide are standard estimates based on UK/EU shoe size conversion conventions, not figures published by Primark directly.
What EU size is a Primark UK 12?
A UK children's size 12 corresponds to approximately EU 30–31. This fits a foot of around 18.5 cm — typical for a 6–7 year old, though foot size varies significantly between children of the same age.
What is a UK junior size 1 in cm?
UK junior 1 is approximately EU 33, corresponding to a foot length of around 20.5 cm. It is the size that follows UK 13 — note that the numbering resets from 13 to junior 1, meaning junior 1 is larger than 13, not smaller.
Do Primark kids' shoes come up small or large?
Primark shoe sizing is broadly consistent with standard UK sizing, but the toe box on many of their styles — particularly trainers and school shoes — is on the narrower side. If your child has wide feet, sizing up one is often sensible regardless of the foot length measurement.
How quickly do children's feet grow?
As a rough guide, children under 3 years can go up a shoe size every 2–3 months. Between ages 3 and 5 it slows to around every 3–4 months. From age 5 onwards, most children go up one size every 4–6 months, though growth spurts can accelerate this. This is why buying one size too large “to last” rarely works well — children may grow into the length before the width catches up, causing rubbing.
The Bottom Line
Primark's decision to publish shoe sizes in UK numbers only is a legacy of their in-store-first model, and it's genuinely inconvenient for anyone shopping online or without their child present. The conversion table in this guide gives you a working approximation — measure your child's foot in cm, add 1 cm of growing room, and look up the corresponding UK size.
The age column in the table is a rough guide only — foot size varies far more between children of the same age than clothing size does. Always go from the foot measurement, not the age.