Quick answer: stand your baby on a sheet of paper, mark the back of the heel and the tip of the longest toe, and measure between the marks with a ruler. That number, plus about half an inch of growing room, is the shoe size. Do both feet and use the longer one. The whole thing takes two minutes, and it's the difference between a shoe that fits and a guess based on age. Below: the paper method step by step, two alternatives for babies who won't stand still, what to do with the number, and the mistakes that throw it off.
What you need
- A sheet of paper bigger than the foot (printer paper is fine)
- A pencil or pen
- A ruler or tape measure with inches or centimeters
- A hard floor, not carpet
- A second person, ideally, to hold the baby steady
Method 1: the paper trace (best for babies who can stand)
- Put the paper on a hard floor and stand your baby on it, barefoot or in the thin socks they'll wear with the shoes. Standing matters: feet spread under weight, and a sitting measurement can run a quarter inch short.
- Hold the pencil straight up, not angled under the foot, and make a mark at the back of the heel and another at the tip of the longest toe. On most babies that's the big toe, but check; on some it's the second toe.
- Measure between the two marks in a straight line. Write it down.
- Repeat on the other foot. One foot is often slightly longer. Size to that one.
- Add growing room. For hard-soled shoes, add half an inch (about 1.3 cm). For stretchy sock shoes, add a quarter inch. That total is the length to shop for.
You don't need to trace the whole foot outline unless you want to check width. Two marks are more accurate than an outline, because the pencil wobbles around curves.
Method 2: the book press (for babies who can't stand yet)
Sit your baby on your lap. Hold a hardcover book upright against a wall and press the baby's heel gently against the book's spine, with the sole flat along a strip of paper or a ruler on your lap. Mark or read where the longest toe lands. Babies curl their toes when touched, so wait a second for the foot to relax, or run a finger along the top of the foot to get the toes to straighten. Measure both feet.
Method 3: measure a shoe that fits (for toddlers who won't cooperate)
If you have a pair that fits well right now, pull out the insole (or measure the inside length of a sock shoe laid flat, heel to toe) and use that number as the length to shop for; it already includes the growing room. If the current pair is getting tight, add a quarter inch. This is the least precise method, but it's better than guessing from age, and it works on a sleeping toddler.
What to do with the measurement
Match the foot length (before adding growing room) to the chart below. The US size assumes the half inch of room built into standard shoe sizing. For Grookz sock shoes, use the right-hand column; our sizes are set by the longest foot each one fits, and the free size finder does the lookup for you.
| Foot length | US size | Typical age | Grookz size |
|---|---|---|---|
| 3.5 in / 8.9 cm | 1 | 0 to 3 months | Size 1 (0 to 6 months) |
| 3.75 in / 9.5 cm | 2 | 3 to 6 months | Size 1 |
| 4.1 in / 10.5 cm | 3 | 6 to 9 months | Size 1 (up to 4.5 in) or Size 2 |
| 4.5 in / 11.4 cm | 4 | 9 to 12 months | Size 2 (7 to 12 months) |
| 4.75 in / 12.1 cm | 5 | 12 to 18 months | Size 2 (up to 5 in) or Size 3 |
| 5.1 in / 13 cm | 6 | 18 to 24 months | Size 3 (13 to 18 months) |
| 5.5 in / 14 cm | 7 | About 2 years | Size 4 (19 to 24 months) |
| 6.1 in / 15.6 cm | 9 | About 3 years | Size 5 (2 to 3 years) |
Between two sizes? Go up. Toes curl in a tight shoe, and a slightly roomy sock shoe stays on because the cuff holds the ankle. The full newborn-to-3-years table with EU and UK sizes is in our baby shoe size chart by age.
Checking width
Baby feet are wide and square at the toes, and width is where most "right size, still uncomfortable" problems come from. If you traced the outline, measure across the widest part of the foot. More than about 60 percent of the length (a 4.5-inch foot wider than 2.7 inches) is a wide foot, and you want a soft knit upper or a shoe sold in wide. With the shoe on, you should be able to pinch a little fabric across the top of the toes. If the shoe is drum-tight across the toes, it's too narrow even if the length is right.
Checking the fit on the foot
- Toe room: with your baby standing, press the front of the shoe. You want about a thumb's width between the longest toe and the end.
- Heel: a hard-soled shoe should hold the heel without slipping when your baby walks. A sock shoe holds at the ankle instead, so a little heel movement is normal.
- Top of the foot: no red line after ten minutes of wear.
- Flex: the sole should bend where the foot bends, at the ball, not in the middle.
- After an hour: take the shoes off and look. Red marks mean too tight somewhere; a shoe that came off on its own means too big or not fastened.
Mistakes that throw the measurement off
- Measuring on carpet. The foot sinks and the pencil angles. Use a hard floor.
- Angling the pencil under the foot. Adds a quarter inch of nothing. Keep it vertical.
- Measuring a sitting baby who can stand. Runs short. Stand them up.
- Measuring the shorter foot. Measure both.
- Measuring first thing in the morning. Feet are slightly bigger by afternoon. Measure later in the day if you can; either way, it's a small difference.
- Using a six-month-old measurement. Feet grow about half a size every two months in the first year. Re-measure before every purchase.
How often to measure
Every six to eight weeks until age two, every three months from two to three, and always before buying. Growth comes in spurts, so a shoe that fit in September can be tight by November. Our month-by-month chart shows the typical pace.
Frequently asked questions
How do I measure my baby's feet at home without a device?
Paper, pencil, ruler. Stand the baby on the paper, mark heel and longest toe, measure between the marks, and add half an inch for a hard-soled shoe or a quarter inch for a sock shoe.
Should I measure my baby's foot sitting or standing?
Standing, if they can stand. Feet spread under weight, and a sitting measurement can run a quarter inch short, which is most of a size.
How much bigger than the foot should a baby shoe be?
About half an inch (1.3 cm) longer than the foot for hard-soled shoes. A quarter inch is enough for stretchy sock shoes.
What if my baby's feet are two different sizes?
Common, and normal. Size to the longer foot. A difference of more than half an inch is worth mentioning at the next pediatrician visit, but a small difference needs nothing.
Can I measure with a shoe-size app?
Phone apps that photograph the foot on a sheet of paper work reasonably well, but the paper-and-pencil method is as accurate and doesn't need a calibration card. Either way, re-measure every couple of months.
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