Baby Growth Curve

What this tool does

A height and weight written in a health booklet says little on its own about whether growth is steady. This chart plots month-age, sex, length and weight against WHO percentile reference lines, so each entry sits visibly near a particular percentile and successive entries form a trend instead of isolated dots.

Common percentile lines at 3, 15, 50, 85 and 97 are built in and interpolated by month-age. As an illustrative reading, a 12-month boy at 76 cm sits near the 50th percentile for length, and 9.6 kg falls roughly between the 50th and 85th for weight. The curve is a positional reference only and never labels a child normal or abnormal.

Multiple entries can be added, and separate profiles let you follow more than one child. The canvas redraws to its container width, and an exported report carries both the curve and the recorded points. Nothing leaves the browser.

The reference lines are a bundled WHO-style percentile dataset interpolated by month-age, so a point can be placed between two tabulated ages rather than snapped to the nearest one. Sex is selected first because boys and girls use different reference values. Length and weight are plotted on separate charts with their own scales; comparing a single number across the two without that separation is a common misreading. Each entry is one visit: a month-age, a length in centimetres and a weight in kilograms. Adding earlier visits joins the points into a line, and it is the direction of that line, rather than any single dot, that usually matters at a check-up. Age is entered in months, so a two-year-old entered as 2 would land in the newborn range and produce a meaningless position. Units are fixed, and inches or pounds will place an entry far outside the expected band. The milestone list is a set of age-appropriate observations to raise with a clinician, not a passed-or-failed test. The chart is a positional reference and never labels a child normal or abnormal; growth assessment also uses head circumference, feeding history and the full series of measurements. Records live only on the current page, so export a report before closing the tab if you want to bring the curve to an appointment.

Key features

• WHO reference lines: Common percentile curves are built in and interpolated by month-age, so a plotted point's position is obvious.
• Trend across visits: Add several month-age entries and the points join into a line rather than standing alone.
• Sex-specific tables: Boys and girls use their own reference data, and switching redraws immediately.
• Multiple profiles: Separate child profiles keep siblings' records independent.
• Milestone prompts: Age-appropriate observations are listed for raising at a check-up.
• Report export: The chart and its records export together for a paediatric appointment.

How to use it

1. Choose sex: Select boy or girl first so the correct reference table loads.
2. Enter age and measures: Fill month-age, length in centimetres and weight in kilograms, one visit per entry.
3. Press Plot: The chart shows the new point and its percentile position.
4. Add earlier visits: Keep adding past month-ages to build a continuous trend line.
5. Export or clear: Export a report to keep, or clear to start a profile for another child.

Things to keep in mind

• Not diagnostic: A percentile shows position only; assessment belongs to a clinician using length, head circumference and feeding history.
• Months, not years: Age is entered in months; writing 2 for a two-year-old places the point in the newborn range.
• Fixed units: Length is centimetres and weight kilograms; inches or pounds shift the plotted point noticeably.
• Reference versions vary: The bundled WHO data is a static release, and other institutions use slightly different standards.
• Local records only: Entries live on the page and vanish on refresh, so keep a separate copy of clinical measurements.