Head circumference is the third measure pediatricians track because it grows fastest of all in the first year — a proxy for how the brain itself is growing. The WHO head-for-age chart plots the same percentile system you already know from weight and height.
How it's measured
A tape is wrapped around the widest part of the head — just above the eyebrows and ears, around the occipital bump at the back. The reading is taken in centimeters, and the same measurement habit (same person, same tape, same spot) makes your home readings far more comparable over time.
What normal growth looks like
At birth a typical head circumference is around 34-35 cm. It grows about 2 cm per month for the first three months, then slows steadily. By 12 months the average is roughly 46-47 cm. Rapid growth in the first months is normal — but a head that crosses percentile lines upward sharply, or a head circumference that stops growing, is what pediatricians watch for.
Tracking it alongside weight and length
The head chart matters most in the first two years, when brain growth is at its peak. Pediatricians interpret head circumference together with weight and length — one isolated reading rarely means anything by itself; the pattern across all three does.
Put all three on one timeline
GrowChart plots weight, height, and head circumference on the same WHO-standard charts so you can see all three trends together at each visit. Create your baby's chart free.
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