BMI Calculator by Age Group
Calculate BMI alongside your age group, since the standard "normal" BMI range is built for adults and reads differently for children, teens, and older adults.
About this bmi calculator by age group
Standard BMI categories assume a typical working-age adult. For children and teens, BMI-for-age percentile charts are the correct standard. For adults over 65, some health guidance allows a slightly higher healthy range than younger adults.
How bmi calculator by age group works
The core calculation is the same BMI formula: Weight (kg) ÷ Height (m)². This version adds a note based on the age you enter, flagging when a standard adult chart may not be the most precise reference.
Common uses
- Getting a quick BMI reading with age-appropriate context
- Understanding why a child's BMI shouldn't be read on the adult scale
- Tracking BMI changes as you age
How to use this tool
- Enter your weight, height, and age.
- See your BMI plus a note on how the standard range may apply differently for your age group.
What to know before using it
For children and teenagers (under 18), a pediatric BMI-for-age percentile chart from a doctor or pediatrician is the medically accurate standard, not the adult BMI categories used here. This is a general wellness tool, not a diagnostic one.
Privacy and browser-first processing
This tool runs entirely in your browser using JavaScript. Nothing you enter is uploaded or stored.
Frequently asked questions
Why does age matter for BMI?
Standard "normal" BMI categories (18.5–24.9) were built around typical working-age adults. Children need growth-based percentile charts, and some guidance allows a slightly wider healthy range for adults over 65.
Should I use this for my child's BMI?
For children and teens, ask a pediatrician for a proper BMI-for-age percentile chart instead, it is the medically correct standard, not the adult categories shown here.