BMI Calculator
Enter your height and weight to work out your Body Mass Index, right in your browser — switch between metric and imperial units and see instantly which range you fall into.
Your measurements
Enter your height and weight to see your result.
Your result
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
How to calculate your BMI
- Choose metric or imperial units, whichever your height and weight are recorded in.
- Enter your height and weight into the fields on the left.
- Click calculate to see your BMI number, category, and the healthy weight range for your height.
What is BMI, and what does it tell you
Body Mass Index is a simple screening measurement that compares your weight to your height. It's calculated by dividing weight in kilograms by height in metres squared, and it's widely used by health organizations as a quick, low-cost way to flag whether someone's weight might fall outside a typical range for their height.
Because the calculation happens entirely in your browser, your height and weight are never uploaded to a server or stored anywhere.
Understanding the categories
BMI doesn't measure body fat directly, and it doesn't account for muscle mass, bone density, age, sex, or ethnicity. It works reasonably well as a population-level screening tool, but it can be misleading for very muscular people, older adults, pregnant people, and some other groups. Treat your result as a general guide rather than a diagnosis, and talk to a healthcare provider for a fuller picture of your health.
The BMI formula, if you want to calculate it by hand
Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = weight (lb) × 703 ÷ height (in)². For example, someone who is 1.75 m tall and weighs 70 kg has a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy weight range. The calculator above does this math for you instantly, in either unit system.
What's a healthy weight for your height?
Rather than one "ideal" number, health guidelines define a healthy weight as a range — the weight your body would be at a BMI between 18.5 and 24.9 for your specific height. Enter your height above and the calculator will show that range converted into kilograms or pounds automatically.
FAQ
Is this BMI calculator really free, with no sign-up?+
Yes. It runs entirely with JavaScript in your browser, so there is no account, no API key, and no limit on how many times you can use it.
Does my height and weight get sent anywhere?+
No. The calculation happens locally on your device. Nothing is uploaded, stored, or logged.
Can I use metric or imperial units?+
Yes. Switch between metric (centimetres and kilograms) and imperial (feet, inches and pounds) at any time.
Is BMI accurate for everyone?+
BMI is a useful screening tool but doesn't account for muscle mass, bone density, age, or sex, so it can be misleading for athletes, older adults, and some other groups. It's best used as a general guide alongside other measurements.
What is a healthy BMI range?+
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range, though individual circumstances vary.
What is the BMI formula, and how do I calculate it manually?+
In metric units, BMI equals weight in kilograms divided by height in metres squared. In imperial units, BMI equals weight in pounds multiplied by 703, divided by height in inches squared.
What is my ideal weight for my height?+
There's no single "ideal" weight, but the healthy BMI range of 18.5 to 24.9 translates into a healthy weight range for your specific height, which this calculator shows automatically once you enter your measurements.
Tools for Weight and Health
How This Calculator Works
Your BMI is computed entirely in your browser using JavaScript, from the standard formula: weight divided by height squared (metric), or weight × 703 divided by height squared (imperial). The healthy weight range shown is calculated the same way, solving for the weight that gives a BMI of 18.5 and 24.9 at your entered height.
Last updated: August 28, 2026.
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