What head circumference measures
Head circumference, also called occipitofrontal circumference (OFC), is the largest distance around the head. It is measured just above the eyebrows and ears and around the most prominent part of the back of the head. Doctors track it in babies because it reflects brain growth, and hat makers use the same measurement to size hats.
How to measure head circumference
- Use a flexible tape measure that does not stretch.
- Place it just above the eyebrows and ears, around the widest part of the back of the head.
- Pull it snug so it presses the hair flat, then read the number.
- Measure three times and record the largest value, to the nearest 0.1 cm.
Normal head circumference by age
For babies up to 36 months, doctors compare the measurement with growth charts and describe it as a percentile. Values between roughly the 3rd and 97th percentile are considered within the typical range. For older children and adults, typical values are shown below.
- Head circumference percentile calculator
- Head circumference chart for boys and girls
- Head circumference to hat size
| Age | cm | Inches | US |
|---|---|---|---|
| Preemie | 25 – 32 | 9.8 – 12.6 | – |
| Newborn | 32 – 36 | 12.6 – 14.2 | – |
| 0 to 3 months | 35 – 40.5 | 13.8 – 15.9 | – |
| 3 to 6 months | 39.5 – 43.5 | 15.6 – 17.1 | – |
| 6 to 12 months | 42 – 47 | 16.5 – 18.5 | – |
| Toddler (1 to 2 years) | 45 – 49 | 17.7 – 19.3 | – |
| 2 to 4 years | 47.5 – 51 | 18.7 – 20.1 | – |
| 5 to 8 years | 50.5 – 53 | 19.9 – 20.9 | 6 ⅜ – 6 ⅝ |
| 9 to 12 years | 52 – 55.5 | 20.5 – 21.9 | 6 ½ – 7 |
| Teen | 54 – 58 | 21.3 – 22.8 | 6 ¾ – 7 ¼ |
| Adult woman | 53 – 59.5 | 20.9 – 23.4 | 6 ⅝ – 7 ½ |
| Adult man | 55 – 60.5 | 21.7 – 23.8 | 6 ⅞ – 7 ⅝ |
Fit tips
- Measure babies when they are calm, ideally lying down with someone holding the head still.
- Use the same tape and the same position every time, so changes reflect growth rather than technique.