BMI Calculator for Kids & Teens

How to Use BMI Calculator for Kids

1. Select your child’s gender. Choose boy or girl; CDC percentile cutoffs differ by gender.
2. Enter your child’s age. Provide both years and months, e.g. 10 years and 3 months, as exact age matters for accurate percentile matching.
3. Input height and weight. Use centimeters and kilograms for the most precise BMI calculation.
4. Click Calculate. The tool computes BMI, compares it with age‑ and gender‑specific CDC percentile cutoffs, and shows the weight category: underweight, healthy weight, overweight or obese.

Benefits of BMI Calculator for Kids

• Uses CDC percentile thresholds (5th, 85th, 95th) designed specifically for children aged 2–18; adult BMI categories do not apply.
• Accounts for age in months as well as years, improving accuracy for growing children.
• Clearly labels the category so parents can understand whether a child’s BMI is within a healthy range for their age.
• No data storage or sign‑up; the tool runs instantly in the browser.

Frequently Asked Questions

Why can’t I use the regular adult BMI calculator for my child?

Because children’s body fat changes as they grow. BMI in kids is interpreted using age‑ and gender‑specific percentiles, not fixed cutoffs. An adult normal BMI could be overweight for a young child.

What do the percentile categories mean?

A child in the 5th‑84th percentile is considered healthy weight. Below the 5th is underweight, 85th‑94th is overweight, and 95th or above is obese. These are screening tools, not diagnoses.

Should I be worried if my child is in the overweight category?

It’s a signal to discuss with your paediatrician. BMI is a screening measure; a doctor will consider growth trends, family history, and other factors before making any recommendations.

Is BMI Calculator for Kids free and private?

Yes — it is 100% free, needs no sign‑up, and everything runs in your browser; your data never leaves your device.