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Measured to 2015 · Published 2026

The century Japan grew, and the year it stopped

Japanese schoolchildren have been measured every April since 1900. The record shows 12.8 cm of growth, eight years the war erased, and a plateau that has now lasted more than twenty years.

+12.8centimetres gained by the average seventeen-year-old boy between 1900 and 2015girls gained 10.9 cm · the war cost 1.9 cm between 1939 and 1948 · nothing has been gained since 1994

Source: School Health Statistics: mean height, weight and sitting height by age

01

A century, measured every April

Japanese seventeen-year-old boys gained 12.8 cm between 1900 and 2015. Girls gained 10.9 cm. Then both stopped.

Every April since 1900, Japanese schools have measured their pupils and sent the figures to the ministry. The result is one of the longest continuous records of human growth anywhere: 107 years of mean height and weight, for thirteen ages, for both sexes.

It is not a smooth curve. It has a hole in it where the war was, a fall on the far side of that hole, four decades of the fastest growth the record has ever seen, and then a flat line that has now run for more than twenty years.

02

The whole record

Two gaps, one fall, one surge, one plateau — the shape of the century is visible in a single line.

The shaded bands are years nobody measured. The lines stop at their edges rather than crossing them, because a line drawn across 1940–1947 would invent eight years of growth that nobody recorded, and would hide the only sustained fall in the entire series.

Switch the measure to weight or leg length, and the age to any of the thirteen the survey publishes. The vertical scale refits to whichever age you choose — a five-year-old and a seventeen-year-old are sixty centimetres apart, and one scale for both would flatten everything worth seeing.

Mean height, weight and leg length, 1900–2015

Japanese schoolchildren, by age and sex. Shaded years were not surveyed.

Height · Age 17 (upper secondary) · 1900–2015 · highest 170.9 cm

no survey1401451501551601651701751900192019401960198020002015cm
  • Boys
  • Girls
  • no survey
Table · Height · Age 17 (upper secondary)
Table · Height · Age 17 (upper secondary)
MeasureValue
Boys · 1900157.9 cm
Boys · 2015170.7 cm
Boys · change over the record+12.8 cm
Boys · highest170.9 cm (1994, 1996, 1997, 1998, 1999, 2001, 2006)
Boys · 1939 to 1948162.5 cm → 160.6 cm (−1.9 cm)
Girls · 1900147.0 cm
Girls · 2015157.9 cm
Girls · change over the record+10.9 cm
Girls · highest158.1 cm (1994, 1996, 1998, 1999, 2000)
Girls · 1939 to 1948152.5 cm → 152.1 cm (−0.4 cm)

Source: School Health Statistics: mean height, weight and sitting height by age · the vertical scale is fitted to the age on screen, so curves at different ages are not directly comparable in size

03

What the war cost, in centimetres

Seventeen-year-old boys came out of the war 1.9 cm shorter than they went in, and it took until 1952 to get it back.

The last pre-war measurement was 1939: 162.5 cm. The survey then stopped for eight years. When it resumed in 1948 the figure was 160.6 cm — a fall of 1.9 cm, undoing more than fifteen years of gain.

Girls lost far less: 152.5 cm in 1939 against 152.1 cm in 1948, a fall of 0.4 cm. The asymmetry is in the record and the record does not explain it.

Recovery was not quick. Boys did not match their 1939 figure again until 1952, thirteen years later. Girls managed it by 1950.

One earlier year is missing too, 1921, for every age from six to seventeen.

04

Then the fastest growth in the record

From 1948 to 1990, seventeen-year-old boys gained 9.8 cm — more than twice what the previous half-century had delivered.

The four decades after the war added 9.8 cm to the average seventeen-year-old boy, against 4.6 cm across the thirty-nine years from 1900 to 1939. Nothing else in the record moves at that rate.

The survey widened as it went. Five-year-olds in kindergarten enter the record in 1948 and had not been counted before; their first two years of the 1950s, 1952 and 1953, are missing.

05

And then it stopped

Boys reached 170.9 cm in 1994 and have never exceeded it. Every year since sits within two millimetres of that figure.

170.9 cm was first recorded in 1994. It was matched in 1996, 1997, 1998, 1999, 2001 and 2006, and never beaten. By 2015 the figure was 170.7 cm. Girls did the same thing: 158.1 cm in 1994, matched four more times, 157.9 cm in 2015.

It would be wrong to call any of those years a peak. The survey samples schools rather than counting every child, so a tenth of a centimetre between two years is noise. What the record supports is not that Japanese children topped out on a particular date — it is that for the last two decades of measurement, they stopped getting taller at all.

Weight did the same. Seventeen-year-old boys averaged 62.0 kg in 1990 and 62.5 kg in 2015.

06

The part that kept changing

Since 1990 the average boy's legs have got 0.8 cm shorter while his seated height grew 1.1 cm. His total height did not move.

Japanese schools also measured sitting height — the height of a seated child, from the seat to the crown — from 1937 until the practice was abandoned after 2015. Subtracting it from standing height gives the length of the legs, and the legs are where the century's growth disproportionately went: from 1937 to 2015 total height rose 6.0% while leg length rose 7.4%.

But that trend reversed while nobody was looking. Between 1990 and 2015 the average seventeen-year-old boy's sitting height rose from 91.0 cm to 92.1 cm, and his legs shortened from 79.4 cm to 78.6 cm. Total height changed by 0.3 cm. A generation of Japanese teenagers is the same height as the one before it and differently proportioned.

Select leg length in the chart above to see it. The line ends in 2015 because the measurement does.