Use this free BMI calculator to work out your body mass index from your height and weight, in pounds and inches or in kilograms and centimetres. It also shows the weight range that falls in the healthy BMI band for your height, and includes a simple tracker so you can log your BMI over time.
BMI Scale
Health Recommendations
Age & Gender Considerations
| Age Group | Recommended BMI Range | Considerations |
|---|
BMI Progress Chart
| Date | Weight | BMI | Category | Change | Action |
|---|
What this BMI calculator does
- Basic BMI: enter your weight and height to see your BMI, its category and the weight range that corresponds to a BMI of 18.5 to 24.9 at your height.
- Age & Gender Adjusted: the same calculation with general notes for different age groups. For adults aged 20 and over, the official categories in the table below apply.
- BMI Tracking: add dated entries to see how your BMI changes, with a chart and a history table. Entries are stored only in your own browser and are not sent to this website; the Clear History button removes them.
How BMI is calculated
BMI is a person’s weight in kilograms divided by the square of their height in metres (CDC). If you enter pounds and inches, the calculator converts them first: pounds × 0.453592 gives kilograms, and inches × 0.0254 gives metres.
Worked example: 150 lb at 5 ft 6 in is 68.04 kg and 1.676 m. 68.04 ÷ (1.676 × 1.676) = 24.2, which falls in the healthy weight range.
BMI categories for adults
For adults aged 20 and over, the CDC bases the categories on BMI alone, regardless of age, sex or race. The calculator labels the healthy weight band as “Normal Weight”.
| BMI (kg/m²) | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to below 25 | Healthy weight |
| 25 to below 30 | Overweight |
| 30 or higher | Obesity (class 1: 30 to below 35, class 2: 35 to below 40, class 3: 40 or higher) |
Important limits of BMI
The CDC describes BMI as a screening measure: it should be considered together with other factors when assessing a person’s health. This calculator is for general information only and is not medical advice. If you have questions about your result, talk with your health care provider.
Frequently asked questions
What is a healthy BMI for an adult?
A BMI from 18.5 to below 25 is the healthy weight range for adults aged 20 and over (CDC adult BMI categories).
Can I use this calculator for a child or teenager?
Not with the adult categories. For ages 2 to 19, the CDC uses a BMI percentile for the child’s age and sex. Use the CDC Child and Teen BMI Calculator instead.
Is my information stored or shared?
The numbers you type are used only in your browser to show the result. Tracking entries are saved in your browser’s local storage on your own device, so clearing your browser data or using Clear History removes them.
Looking for more? See all our free health and fitness calculators.