A hat that's too big slips over your baby's eyes; one that's too tight leaves a red mark and gets left at home. Getting the size right makes all the difference—and it's easier than you'd think once you know your baby's head measurement. Here's a simple guide to baby hat sizes by age, how to measure at home, and how to get a comfy, secure fit.
Baby hat sizes work by head circumference
Unlike some clothing, hats are sized by one simple number: your baby's head circumference. Age is only a rough guide because babies' heads grow at their own pace, so the most reliable way to choose is to measure. Many hats are also labelled by age range, but if you can measure, you'll get a far better fit.
Baby Hat Size Chart by Age
Use this as a starting point, then measure to confirm. Head sizes vary from baby to baby, so treat the age ranges as a guide, not a rule.
| Age | Head Circumference (inches) | Head Circumference (cm) |
|---|---|---|
| Preemie | Up to 12.5" | Up to 32 cm |
| Newborn (0-3 Months) | 13" - 15" | 33 - 38 cm |
| 3-6 Months | 15" - 17" | 38 - 43 cm |
| 6-12 Months | 17" - 18.5" | 43 - 47 cm |
| 12-24 Months | 18.5" - 19.5" | 47 - 50 cm |
| 2-3 Years | 19.5" - 20" | 50 - 51 cm |
How to measure your baby's head
All you need is a soft, flexible measuring tape (the kind used for sewing). If you don't have one, use a piece of string and then measure it against a ruler.
- Position the tape: wrap it around the widest part of your baby's head—about halfway up the forehead, just above the eyebrows and ears, and around the back where the head sticks out most.
- Keep it snug, not tight: the tape should sit flat against the head without digging in.
- Read the number: that measurement is your baby's head circumference—match it to the chart or the hat's size label.
Babies wriggle, so don't worry about perfection—measure when they're calm or sleeping, and a close reading is plenty. It's the same principle as measuring for the right baby shoe size: a quick measurement beats guessing by age.
Getting a safe, comfortable fit
The right hat is snug enough to stay on but never tight. A few things to check:
- No red marks: if the hat leaves a line on the forehead, it's too small.
- Doesn't slip over the eyes: if it slides down, it's too big—size down or choose a tie-on style.
- Soft, stretchy fabric: a little stretch means the hat grows with your baby and fits comfortably.
- No loose ties or cords near the neck: for safety, avoid anything that could wrap or tangle, and never leave a hat on for sleep.
Room to grow
Babies' heads grow quickly in the first year, so if you're between sizes, size up rather than down—a slightly roomy hat still works, while a tight one gets outgrown in weeks. Stretchy knit styles are the most forgiving, adapting as your baby grows. For how sizing varies across pieces and brands, our guide on whether baby clothes run big or small is worth a look.
The takeaway
Baby hats are sized by head circumference, so a quick measurement around the widest part of the head is the surest way to a good fit. Use the age chart as a starting point, size up if you're between sizes, and choose soft, stretchy fabrics that stay snug without leaving a mark. For soft, breathable pieces—hats included—browse our organic cotton baby clothes.