Plot No. 6 · Health & Fitness
BMI Calculator
Work out your body mass index from your height and weight in metric units. BMI gives a quick indication of whether your weight sits in a healthy range for your height.
BMI is a rough screening measure that does not account for muscle mass, body composition or age. It is not a diagnosis. Speak to a healthcare professional for personalised advice.
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How body mass index is calculated
Body mass index is a single number that relates your weight to your height, used as a fast screening check for whether your weight sits in a healthy range. This calculator takes your weight in kilograms and height in centimetres, converts the height to metres and divides your weight by the square of that height.
The resulting BMI is then placed into a category. Below 18.5 is underweight, 18.5 up to 25 is a healthy weight, 25 up to 30 is overweight, and 30 or above is in the obese range. The category gives quick context to the raw number.
How to use the BMI calculator
- Enter your weight in kilograms.
- Enter your height in centimetres.
- Read your BMI to one decimal place and the weight category it falls into.
Worked examples
An average adult
Inputs: Weight 70 kg, height 175 cm.
Result: A BMI of about 22.9, which sits in the healthy weight range of 18.5 to 24.9.
A taller, heavier frame
Inputs: Weight 95 kg, height 180 cm.
Result: A BMI of about 29.3, which falls in the overweight band just below the obese threshold of 30.
Limitations and common mistakes
Edge cases and limitations
- BMI uses metric units only here, so convert pounds to kilograms and feet and inches to centimetres before entering them.
- It does not distinguish muscle from fat, so it can overstate body fat in very muscular people and understate it in older adults who have lost muscle.
- It is a population-level screening measure, not a diagnosis, and says nothing about where fat is carried or your overall health.
Common mistakes
- Entering height in metres rather than centimetres, which produces a wildly wrong BMI.
- Treating a single BMI reading as a verdict on health rather than one data point to discuss with a professional.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres. For example, a person who is 1.75 m tall and weighs 70 kg has a BMI of 70 divided by 3.0625, which is about 22.9.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above falls into the obese range.
Is BMI accurate for everyone?
BMI is a useful general guide but it has limits. It can overestimate body fat in very muscular people and underestimate it in older adults who have lost muscle. Use it as a starting point, not a final verdict.
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Related guides
What Is a Good BMI, and What It Doesn't Tell You
A good adult BMI is 18.5 to 24.9, but it is only a rough screen. How to read your number and the limits BMI does not show.
Free alternative to the Calculator.net BMI calculator
Work out your BMI from your height and weight and see which category it falls in. Free BMI guide and calculator, no sign-up.