Japan Children and Families Agency (2023 survey) · Japan Standard
Baby Head Circumference Percentile Calculator — Japan Standard
Enter your child's date of birth, measurement date, and head circumference to see their percentile on Japan's official 2023 national infant growth survey. Note: this survey only measures head circumference up to age 3. Calculated entirely in your browser — nothing is uploaded or stored.
Please enter a valid date of birth (child must be under 3 years old — this survey does not cover older children), measurement date, and head circumference.
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3rd50th97th
⚠ Educational tool, not medical advice. This calculator uses Japan's official 2023 national infant growth survey (published December 2024), which publishes only 7 discrete percentile points (3rd/10th/25th/50th/75th/90th/97th) rather than a continuous curve like WHO's. Results are linearly interpolated between those published points — a coarser approximation than the WHO calculators on this site, not a smooth curve. Starting with this 2023 survey, head circumference is only measured for children under 3 — this tool does not cover older children. Readings below the 3rd or above the 97th percentile are outside the published range and shown as a range rather than an exact number. A single reading is not a diagnosis — track the trend in your child's maternal and child health handbook (母子健康手帳) growth chart and discuss with a pediatrician.