How much should a 1-year-old weigh?

The WHO average at 12 months is about 9.6 kg (21 lb 4 oz) for a boy and 8.9 kg (19 lb 12 oz) for a girl. That is the 50th percentile; a healthy one-year-old ranges from roughly the 3rd to the 97th percentile. The complete tables for both sexes are above.

Should a baby triple their birth weight by 1 year?

Tripling the birth weight by 12 months is the common rule of thumb, and many babies land close to it. It is a typical pattern, not a strict requirement — babies who started large or small, or grow at their own pace, may triple a bit earlier or later. A steady curve is the real reassurance.

Why has my 1-year-old barely gained weight lately?

Because growth slows dramatically after the first birthday — a toddler gains only a few pounds across the whole second year. Add a more active body and a famously erratic appetite, and the scale can look almost flat for stretches. As long as your child follows their own curve and stays energetic, this is expected.

Is the 1-year weight different for boys and girls?

Yes. Boys average around 0.7 kg (roughly 1.5 lb) heavier than girls at the 50th percentile at 12 months, so the WHO uses separate charts. Compare your child to the chart for their sex rather than to a single blended average.

My 1-year-old is a picky eater and small — is that a problem?

Selective, up-and-down eating is extremely common at one year and usually matches the lower calorie needs of slower growth. A smaller toddler who tracks steadily along their own percentile, is active and meeting milestones is typically fine. Raise it with your pediatrician if the growth curve itself flattens or drops across visits.

What is the average length and head circumference at 12 months?

About 75.7 cm (29.8 in) length for boys and 74.0 cm (29.1 in) for girls at the 50th percentile, with average head circumference near 46.1 cm (18.1 in) for boys and 44.9 cm (17.7 in) for girls. The full percentile tables for length and head circumference are on this page.

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WHO Growth Standards

Average Weight for a 12-Month-Old (WHO Percentiles)

The average weight of a 1-year-old boy and girl, the full percentile range from P3 to P97, and where your baby lands — using the WHO Child Growth Standards.

Is your 12-month-old's weight typical?

A quick weight-only check. For length, head circumference and exact age, use the full tool below.

Sex

Your baby's weight

Open the full growth percentile tool

Weight, length and head circumference at your baby's exact age in days.

Reference ranges from the WHO Child Growth Standards — not medical advice. Every baby grows differently.

Weight, length & head circumference percentiles at 12 months

The WHO reference values for a {{age}}-month-old, from the 3rd to the 97th percentile, for boys and girls. P50 is the average; anywhere from P3 to P97 is a normal, healthy measurement. Numbers are calculated directly from the WHO Child Growth Standards.

Weight-for-age

Sex	P3	P15	P50	P85	P97
Boys	7.8 kg17 lb 5 oz	8.6 kg19 lb 0 oz	9.6 kg21 lb 4 oz	10.8 kg23 lb 13 oz	11.8 kg26 lb 1 oz
Girls	7.1 kg15 lb 12 oz	7.9 kg17 lb 6 oz	8.9 kg19 lb 12 oz	10.2 kg22 lb 7 oz	11.3 kg25 lb 0 oz

Length-for-age

Sex	P3	P15	P50	P85	P97
Boys	71.3 cm28.1 in	73.3 cm28.8 in	75.7 cm29.8 in	78.2 cm30.8 in	80.2 cm31.6 in
Girls	69.2 cm27.2 in	71.3 cm28.1 in	74.0 cm29.1 in	76.7 cm30.2 in	78.8 cm31.0 in

Head circumference-for-age

Sex	P3	P15	P50	P85	P97
Boys	43.6 cm17.2 in	44.7 cm17.6 in	46.1 cm18.1 in	47.4 cm18.7 in	48.5 cm19.1 in
Girls	42.3 cm16.7 in	43.5 cm17.1 in	44.9 cm17.7 in	46.3 cm18.2 in	47.4 cm18.7 in

P50 (highlighted) is the median — the true "average". A baby is not "behind" at P15 or "ahead" at P85; both are well within the normal range. The trend along a baby's own curve over time matters far more than a single percentile.

One Year: Tripling Birth Weight, Then a Big Slowdown

By the first birthday most babies have roughly tripled their birth weight — the headline milestone for this age. A 3.3 kg (about 7 lb) newborn commonly lands near 9–10 kg at a year. As with doubling at 4–6 months, it is a typical pattern rather than a pass/fail target; babies born large or small reach it on their own timeline.

The second big theme at 12 months is deceleration. Growth slows markedly after the first birthday: gain drops toward only about 1.4–2.3 kg (3–5 lb) across the entire second year, versus the ~6 kg piled on in year one. Toddlers also get taller and more mobile, so many look leaner even as the scale barely moves — that is healthy, not a stall.

Appetite famously becomes erratic around now: a walking, exploring one-year-old is easily distracted and may eat heartily one day and pick the next. Because growth has slowed, that lighter appetite matches lower calorie needs. A one-year-old who keeps following their own curve, stays active and hits milestones is on track even through the fussy-eating phase.

Tripling the birth weight by 12 months is the classic marker, and growth slows sharply after. Toddlers often look leaner as they get taller and more active — a near-flat scale can be perfectly normal at this age.

Sources & Limitations

Every number on this page is computed from the World Health Organization Child Growth Standards (2006) — the international reference for how breastfed children grow under optimal conditions, used by pediatricians worldwide. These are population reference ranges, not targets to hit.

Reference ranges, not medical advice — every baby grows differently, and a healthy baby can sit anywhere from the 3rd to the 97th percentile. A low or high percentile is not a problem by itself; a curve that suddenly flattens, drops or jumps across visits is what's worth a conversation. For anything that worries you, talk to your pediatrician.

Watch the curve, not just today's number

Doudou plots your baby's weight, length and head circumference on the WHO growth curves as you log — so you see the trend that actually matters, not a one-off weigh-in. Synced between both parents.

Doudou — the baby tracker for both parents

Frequently Asked Questions

How much should a 1-year-old weigh?: The WHO average at 12 months is about 9.6 kg (21 lb 4 oz) for a boy and 8.9 kg (19 lb 12 oz) for a girl. That is the 50th percentile; a healthy one-year-old ranges from roughly the 3rd to the 97th percentile. The complete tables for both sexes are above.
Should a baby triple their birth weight by 1 year?: Tripling the birth weight by 12 months is the common rule of thumb, and many babies land close to it. It is a typical pattern, not a strict requirement — babies who started large or small, or grow at their own pace, may triple a bit earlier or later. A steady curve is the real reassurance.
Why has my 1-year-old barely gained weight lately?: Because growth slows dramatically after the first birthday — a toddler gains only a few pounds across the whole second year. Add a more active body and a famously erratic appetite, and the scale can look almost flat for stretches. As long as your child follows their own curve and stays energetic, this is expected.
Is the 1-year weight different for boys and girls?: Yes. Boys average around 0.7 kg (roughly 1.5 lb) heavier than girls at the 50th percentile at 12 months, so the WHO uses separate charts. Compare your child to the chart for their sex rather than to a single blended average.
My 1-year-old is a picky eater and small — is that a problem?: Selective, up-and-down eating is extremely common at one year and usually matches the lower calorie needs of slower growth. A smaller toddler who tracks steadily along their own percentile, is active and meeting milestones is typically fine. Raise it with your pediatrician if the growth curve itself flattens or drops across visits.
What is the average length and head circumference at 12 months?: About 75.7 cm (29.8 in) length for boys and 74.0 cm (29.1 in) for girls at the 50th percentile, with average head circumference near 46.1 cm (18.1 in) for boys and 44.9 cm (17.7 in) for girls. The full percentile tables for length and head circumference are on this page.