Disclaimer: This BMI calculator is for general informational purposes only and is not medical advice. BMI does not account for muscle, build, age, or sex. Consult a qualified healthcare professional for health decisions.
About this BMI calculator
This free BMI calculator works out your Body Mass Index from your height and weight, in either metric (centimetres and kilograms) or US units (feet, inches, and pounds). BMI is a simple, widely used screening number that estimates whether your weight is in a healthy range for your height. The result updates instantly in your browser and nothing is stored.
BMI is grouped into ranges: under 18.5 is underweight, 18.5 to 24.9 is a normal weight, 25 to 29.9 is overweight, and 30 or above is in the obese range. BMI is a general guide, not a diagnosis, and it does not account for muscle, build, age, or sex, so treat it as a starting point and talk to a health professional for personal advice.
How to use it
Pick your unit system, enter your height and weight, and read your BMI and category instantly.
How the BMI calculator works
BMI (Body Mass Index) is a quick way to estimate whether your weight is in a healthy range for your height. It is calculated with one simple formula:
BMI = weight (kg) ÷ height (m)²
If you enter US units, the tool converts your pounds and feet/inches to kilograms and metres first, then applies the same formula. Your result is matched to a standard category: under 18.5 is underweight, 18.5–24.9 is a healthy weight, 25–29.9 is overweight, and 30 or above is in the obese range.
Example calculation
A person who weighs 70 kg and is 1.75 m tall: 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = BMI 22.9 — a healthy weight.
Key features
Works in both metric (cm, kg) and US (ft, in, lb) units
Instant result with your weight category
Runs fully in your browser — your data is private
Mobile-friendly and free, with no sign-up
When to use it
Tracking your weight and fitness progress
A quick health check before a doctor's visit
Setting realistic weight goals
Understanding standard BMI weight categories
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. The tool also converts US units for you.
What is a healthy BMI?
A BMI between 18.5 and 24.9 is generally considered a healthy range.
Is BMI accurate for everyone?
BMI is a general guide and does not account for muscle or build, so treat it as a starting point.
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