Barefoot Shoe Size Conversion for Kids
Joyo, Vivobarefoot, Xero, plus EU, US and UK, converted off the one number that does not lie: your child's foot length in millimeters.
There is no standard barefoot size, so each brand fits differently. Measure your child's foot in millimeters, add 10 to 12mm of growth room, then match that target to each brand's published inner length. EU sizing is the most stable cross-brand reference; US splits confusingly into toddler and youth scales. Check toe-box width too, since it varies more than length.
If you have ever ordered the same printed size in two barefoot brands and gotten two different fits, you are not imagining it. There is no enforced standard for what an "EU 24 kids" actually measures inside. Each brand picks a last and a growth-room convention and prints a number. This guide converts between the brands parents actually compare, using the one thing that does not lie: your child's foot length in millimeters.
Why barefoot brands size so differently
Three reasons stack up. First, the last: the foot-shaped mold each brand builds around has a different length and width. Second, the growth-room convention: some brands bake 10mm of toe room into the size, others list the bare inner length and expect you to add it. Third, the system itself: EU steps in about 6.6mm, US in about 8.5mm, and the US toddler-to-youth relabel resets the numbers around age 5. Put those together and a single foot can be three different printed sizes across three brands.
Barefoot kids size conversion by foot length
Measure your child's foot first (here is the method), then read across. This maps a measured foot length to the size Joyo and Vivobarefoot recommend, with about 10 to 12mm of growth room already built into the size each brand returns. Xero is handled separately below, because Xero does not publish a foot-length-per-size chart.
| Child's foot length | Joyo Kids | Vivobarefoot Primus Kids | EU equivalent | US kids (toddler/youth) |
|---|---|---|---|---|
| 120mm | EU 21 | EU 22-23 | 21 | 5.5T |
| 130mm | EU 22 | EU 24 | 22 | 6.5T |
| 140mm | EU 23 | EU 26 | 23-24 | 8T |
| 150mm | EU 25 | EU 27 | 25 | 9.5 |
| 160mm | EU 26 | EU 28-29 | 26-27 | 10.5 |
| 170mm | EU 28 | EU 30 | 28 | 11.5 |
Foot-length to size taken from each brand's official kids size guide (Joyo and Vivobarefoot Primus Kids), June 2026, assuming 10 to 12mm of growth room added to the measured foot. Vivobarefoot publishes its sizing per their official chart; Joyo bakes the growth room into the last. Always confirm against the current spec on the brand's own size page before ordering.
Xero kids sizing: use their US/EU conversion, not foot length
Xero is the exception. Xero does not publish a foot-length-per-size chart for its kids shoes. Their official guidance is to order your child's normal size, and they publish a straight US to EU conversion instead. So do not try to convert a millimeter measurement into a Xero EU size, there is no published basis for it. Find your child's usual US kids size and read the EU equivalent off Xero's own table:
| Xero line | US | EU |
|---|---|---|
| Little Kids | US 6 | EU 22 |
| Little Kids | US 7 | EU 23 |
| Little Kids | US 8 | EU 24 |
| Little Kids | US 9 | EU 25 |
| Little Kids | US 10 | EU 27 |
| Little Kids | US 11 | EU 28 |
| Big Kids | US 12 | EU 30 |
| Big Kids | US 13 | EU 31 |
| Big Kids | US 1 | EU 32 |
| Big Kids | US 2 | EU 33 |
| Big Kids | US 3 | EU 34 |
| Big Kids | US 4 | EU 36 |
Source: Xero Shoes official kids size conversion (Little Kids and Big Kids lines), June 2026. Xero's guidance is "order your normal size." Because Xero runs narrow through the toe box, wide-footed kids may still need a different brand even when the length is right.
EU, US and UK: reading the same foot three ways
The systems do not convert cleanly because they use different step sizes and reference points. As a working rule for kids:
- EU to US youth: subtract about 18 from the EU number for a rough US youth size in the 25 to 33 range. It is approximate by design.
- EU to UK: subtract about 17.5 from the EU number.
- The trap: the US splits into "toddler" and "youth" scales that both run through the low double digits, so a "US 12" can be two different shoes. EU is the more stable reference for cross-brand shopping.
The width problem most charts ignore
Length conversion is only half the job. Toe-box width varies even more between brands than length does, and a barefoot shoe lives or dies on toe-box width. Xero's Prio Youth runs narrow, Vivobarefoot's Primus is medium-wide, and Joyo and Whitin run wide. A kid with wide feet who converts purely on length will still get a bad fit in a narrow last. If that is your child, start with the wide-feet fit research and the wide-toddler-feet guide before you convert anything.
How Joyo kids sizing converts
Joyo sizes to the foot with about 10mm of growth room already in the last, so once you have a millimeter measurement you size to it directly rather than guessing up. The First Walker (TinyToes) and Everyday Sneaker (KidStride) cover the toddler-through-youth range, and the wide First Walker Wide (LittleSteps) adds room for fuller feet. For the full side-by-side against every brand in this table and more, the Kids Barefoot Shoe Index is the hub, and the parents' guide covers how to choose. If you are mid-purchase and stuck between two sizes, the size-up guide settles it.
Frequently asked
Do barefoot shoes run big or small?
It depends on the brand. Vivobarefoot's youth lines tend to run slightly short at the small end, Xero's Prio Youth runs narrow rather than short, and Joyo and Whitin run wide. There is no industry standard, so convert from your child's measured foot length against each brand's inner-length spec rather than trusting the printed size.
How do I convert Vivobarefoot to Xero kids sizing?
They convert differently, so do not assume the same EU number. Vivobarefoot publishes a foot-length chart, so for a roughly 140mm foot plus growth room you land near an EU 26 on Vivobarefoot's official chart. Xero does not publish a foot-length chart at all; their guidance is to order your child's normal size and use their US to EU conversion (for example US 10 Little Kids is EU 27). Xero also runs narrower, so a wide-footed child may need a different brand even at the right length.
What is EU size 24 in US kids?
EU 24 is roughly a US 8 toddler or US 7.5 youth depending on the scale and brand, with a foot length around 145mm. The US toddler and youth scales overlap in the low double digits, so EU is the more reliable reference when shopping across brands.
Why is my kid a different size in every brand?
Because each brand uses a different last and a different growth-room convention, and the EU, US and UK systems use different step sizes. A single foot can be three printed sizes across three brands. The fix is to size off your child's foot length in millimeters and each brand's published inner length, not the number on the box.
Is EU sizing more accurate for kids than US?
EU sizing is more stable for cross-brand kids shopping because it steps consistently in about 6.6mm and does not reset between toddler and youth the way US sizing does. It is still tied to a brand's last, so it is a better reference but not a guarantee. Measured foot length remains the ground truth.
How wide are barefoot shoes compared to regular shoes?
Barefoot shoes are noticeably wider through the toe box so toes can splay, but width still varies by brand. Xero's youth runs narrow, Vivobarefoot is medium-wide, and Joyo and Whitin run wide. Converting on length alone misses this, so wide-footed kids should check toe-box width specifically.
