Measure your baby boy’s foot standing barefoot from heel to longest toe, repeat on both feet, and size to the longer one; sandals should leave about 1 cm of room at the toe.
The method below uses a wall, a piece of paper, and a ruler. Once you have the number in centimeters, the sandal chart at the bottom tells you which US size to grab.
How Do You Measure A Baby’s Foot At Home?
Stand the child barefoot on paper with the heel touching a wall, then measure from the wall edge to the tip of the longest toe. Everything in the procedure depends on standing — a foot spreads and lengthens under body weight, so a seated measurement runs short.
- Lay a sheet of paper flush against a wall on a hard floor, not carpet or a bed.
- Have your baby stand with the heel against that wall. Babies and early walkers often need your hand under one arm to steady them — a knee on the floor beside them usually does the trick.
- Draw a line at the tip of the longest toe, not automatically the big toe.
- Mark the back of the heel on the paper, then measure between the two marks in centimeters with a ruler.
- Repeat the whole process on the other foot.
Use the longer foot’s number.
When your child absolutely won’t stand still, hold the paper up against the sole of the foot while the foot is flat on the floor and mark the longest toe and the heel. It’s less precise than the wall method, but far better than guessing from age alone.
Sandal Fit: How Much Room Should You Leave?
Allow roughly a thumb-width — about 1 centimeter, or 0.4 inches — of space between the longest toe and the front edge of the sandal.
The allowance matters more on an open sandal than a closed shoe, because a snug toe box has nowhere to give. Sandals that leave no room at the front will rub the toes raw; sandals that are too loose make a toddler curl their toes to hold them on, which is worse for developing feet than a slightly big pair.
Two extras worth checking before you buy:
- Width, not just length. Width can matter as much as length. If a sandal slips off the heel or feels narrow across the top, the length may be right while the width is wrong — John Lewis’s fit guide includes separate width-measuring steps for exactly this reason.
- Toe movement. A correct fit lets the toes move and the heel sit back in the heel cup rather than perched on the edge.
When the number checks out but something still feels off, it’s usually the strap arrangement rather than the size, which is why we tested the designs that actually stay on a squirming foot in our roundup of the best baby boy sandals for new walkers.
| Foot Length (cm) | US Sandal Size | Rough Age Window |
|---|---|---|
| 11.5–11.9 | 4.5 | 0–6 months |
| 12.0–12.5 | 5 | 3–9 months |
| 12.6–13.1 | 5.5 | 6–12 months |
| 13.2–13.7 | 6.5 | 9–15 months |
| 13.8–14.3 | 7.5 | 12–18 months |
| 14.4–14.9 | 8.5 | 15–21 months |
| 15.0–15.5 | 9 | 18–24 months |
| 15.6–16.1 | 9.5 | 24 months and up |
Why Age Charts Alone Get It Wrong
Age ranges are rough guides, never a substitute for a measured foot length. Baby charts commonly break sizes into bands like 0–3, 3–6, 6–9, 9–12, 12–18, and 18+ months, and kids’ charts cover 0–11 months with the heel aligned to a base line and the size read at the longest toe. Those bands assume an average foot, and plenty of healthy babies sit a half or full size away from average.
Two children the same age can easily differ by a full sandal size. That’s why every major fit guide — including Nike’s kids’ footwear sizing guide — routes you back to measuring the foot rather than reading the birthday off a chart.
Re-measure every two to three months in the first year and at every growth spurt after that. Feet grow in bursts, so a sandal that fit in May can be tight by July, and a tight sandal is the one fit problem a toddler can’t tell you about in words.
For a printable chart to stand the foot on, most retailers publish one, and New Balance’s kids’ size guide walks through the same heel-to-toe method if you want a second reference while you measure.
Wrapping Up The Fit
Write the number down once and the rest is simple: heel against the wall, longer foot wins, add about a centimeter, and re-check every couple of months.
- Measure standing, never sitting.
- Always measure both feet; size to the larger one.
- Mark the longest toe, which isn’t always the big toe.
- Leave roughly 1 cm of room at the front of the sandal.
- Check width when length looks right but the fit doesn’t.
- Re-measure every 2–3 months until age two.
FAQs
Can I measure my baby’s feet while they’re asleep?
You can, but expect a smaller number than you’d get standing. A foot spreads and lengthens once body weight is on it, so a sleeping measurement can read up to a half size short. If you have no other option, add a few millimeters of allowance and plan to re-measure while your child is upright before committing to a size.
How often should I check the fit on a growing toddler?
Every two to three months through the first year, then quarterly or at each growth spurt. Toddler feet grow in bursts rather than steadily, so a sandal can fit in early summer and pinch by late summer.
What if one foot measures bigger than the other?
That’s normal, and it’s why every fit guide says to measure both feet. Always size to the longer foot and let the smaller one have a bit of extra room. If the difference between feet looks like more than a full size, mention it at your child’s next checkup.
References & Sources
- Nike. “Kids’ Footwear Size Chart and Fit Guide.” Standing heel-to-toe measurement method and kids’ sizing guidance.
- New Balance. “Kids’ Shoe Size Guide.” Kids’ fit measurement steps and chart-reading instructions.
- John Lewis. “How to Measure Children’s Feet.” Includes width-measuring steps and growth-room allowance guidance.