How is this different from a weight percentile?

Weight only means something read together with height, whereas arm circumference carries its own information about how much muscle and fat are on the arm. It is also unaffected by oedema, which can leave weight normal or high in a child who is not.

Why does it stop at 5 years?

That is where WHO’s table stops — 91 to 1856 days, precisely. There is nothing published to check older ages against, so nothing is extrapolated here.

How do I measure it properly?

Find the midpoint between the tip of the shoulder and the tip of the elbow, let the arm hang relaxed, and run the tape level around it — flat against the skin, not tight. Pulling it tight reads low, and half a centimetre is several percentiles on this measurement.

Calculators

Arm circumference calculator

The circumference around the middle of the upper arm, placed against the reference. WHO uses it as a field screen and publishes it for 3 months to 5 years.

Fill in the fields to see the position

How to read this number

Mid-upper arm circumference (MUAC) is what WHO uses to screen for acute malnutrition in the field. It has two advantages weight and height do not: a tape measure is all it takes — no scales, no stadiometer — and it is unaffected by oedema, which inflates weight and can hide the children who most need attention.

It measures the arm at its midpoint: halfway between the tip of the shoulder and the tip of the elbow, arm hanging relaxed, tape flat against the skin but not biting into it. Pulling tight or pressing in reads low, and the range this indicator moves across is narrow — half a centimetre is several percentiles.

Only WHO publishes an arm-circumference-for-age table, covering 3 months to 5 years. Every other region routes to that same table, so switching standards shows the same figures. That is stated plainly rather than dressing one table up as several.

The standard behind it

This calculator uses WHO Child Growth Standards (2006) · WHO Growth Reference (2007)’s LMS parameters. Ages 0–5 use the 2006 Child Growth Standards and 5–19 the 2007 growth reference; the two join at five.

The source tables are taken straight from who.int, data version 2026-09-03. Ages beyond what a standard covers are never extrapolated — the page says there is nothing there.

Common questions

How is this different from a weight percentile?: Weight only means something read together with height, whereas arm circumference carries its own information about how much muscle and fat are on the arm. It is also unaffected by oedema, which can leave weight normal or high in a child who is not.
Why does it stop at 5 years?: That is where WHO’s table stops — 91 to 1856 days, precisely. There is nothing published to check older ages against, so nothing is extrapolated here.
How do I measure it properly?: Find the midpoint between the tip of the shoulder and the tip of the elbow, let the arm hang relaxed, and run the tape level around it — flat against the skin, not tight. Pulling it tight reads low, and half a centimetre is several percentiles on this measurement.