Child Height and Weight Tracker

Worked example

Example: an 8-year-old boy at 127 cm and 25 kg may show approximate height and weight percentiles near the middle of the reference range, with BMI-for-age in a typical band. Results vary with the simplified curves used here—not clinical charting software.

How it works

The calculator compares entered height and weight to simplified sex-specific reference curves for ages 2–18 to estimate approximate percentiles and BMI-for-age category. Optional parent heights use the mid-parental height formula for an adult-height estimate with a typical range. These curves are educational approximations—not official WHO or CDC growth charts—and may differ from clinical tools.

Limitations

Percentiles and BMI-for-age use simplified reference curves for ages 2–18. They are not official WHO or CDC growth-chart values and must not be used for diagnosis, treatment planning, or clinical decisions.

Privacy and file handling

Your data stays on your device and is not uploaded.

Accuracy & methodology

This section documents how the calculator works, what it leaves out, and when results were last reviewed. Figures are educational estimates—not professional advice—and are not labeled "current" unless tied to automatically updated reference data.

Formula source or methodology

Height and weight compared to simplified sex-specific reference curves for ages 2–18 to estimate approximate percentiles and bands. BMI-for-age category from computed BMI. Optional mid-parental height: (mother + father ± offset) / 2 with a typical ± range—not CDC LMS z-scores.

Jurisdiction

Educational reference (not clinical charting software)

Unit system

Metric or US for child and parent heights/weights

Rounding method

Percentiles and BMI round for display; underlying curves are approximate

Assumptions

• Ages 2–18 only
• Simplified reference data embedded in the tool—not live WHO/CDC tables
• Steady measurement at one point in time

Known omissions

• Not medical advice. Does not diagnose, treat, or replace clinical assessment.
• Official WHO or CDC growth-chart LMS values
• Premature infant corrected age
• Syndromic growth patterns and endocrine workups
• Down syndrome or other condition-specific charts

Test cases (automated)

• Age 8, valid height/weight returns percentile bands
• Age under 2 or invalid measurements are rejected

Version & last verified

Logic version 1.0. Content and formulas last verified 2026-07-24.

Important notice

This child growth calculator is for educational purposes only and is not medical advice. Height and weight percentiles, BMI-for-age categories, and adult-height estimates use simplified reference curves—they are not official WHO or CDC growth-chart results and must not be used for diagnosis or treatment. Consult a qualified healthcare professional for personal health decisions.