Home › Calculators › BMI Calculator

BMI Calculator

Calculate your Body Mass Index and see your healthy-weight range, instantly and privately. Enter your height and weight in metric or imperial units, and the calculator returns your BMI, its category and the healthy weight range for that height. A fast, useful screening measure — with nothing uploaded.

Units

Height

Weight

Age (optional)

What is BMI?

Body Mass Index (BMI) is a simple screening number that relates your weight to your height. It is worked out by dividing your weight in kilograms by your height in metres squared (kg/m²). BMI gives a quick sense of whether someone is underweight, at a healthy weight, overweight or obese, and it is widely used by doctors and public health bodies as an initial check. For adults the standard categories are: below 18.5 is underweight, 18.5 to 24.9 is healthy, 25 to 29.9 is overweight and 30 or above is obese. Crucially, BMI is a screening tool rather than a diagnosis. It does not tell muscle from fat, so a very muscular person can be classed as overweight despite being lean, and it ignores age, sex and where fat is stored. Use it as a starting point and treat the number as one indicator among many when you think about your health.

How to use this BMI calculator

Choose Metric (kg, cm) or Imperial (lb, ft/in) units.
Enter your height and weight in the matching unit.
Optionally add your age.
Click Calculate BMI to see your BMI, category and healthy weight range.

Example

A height of 170 cm and a weight of 70 kg gives a BMI of 24.2 kg/m², which falls in the Healthy / normal category. The calculator also shows the healthy weight range for that height as between 53.5 kg and 72 kg.

Who is this BMI calculator for?

This BMI calculator is useful for anyone who wants a quick, at-a-glance idea of how their weight relates to their height. The adult formula is the same for everyone, but different groups tend to use it a little differently.

Men: Men often check their BMI for men alongside waist or body-fat readings, since BMI alone does not tell muscle from fat. Treat it as one signpost next to activity and how you feel.
Women: Women use a BMI for women as a quick screening number and to track changes over time. The numbers are the same as for men, but body-composition differences mean it reads best with a waist measurement.
Seniors: Seniors may rely less on a single number and more on trends, because muscle mass and bone density shift with age. A BMI for seniors is best viewed alongside other health indicators.
Teens: Teens and parents can use a BMI for teens as a rough guide, but the adult categories do not directly apply — children and teens are judged against age- and sex-specific percentiles.

BMI chart and table — healthy weight range by height

These adult reference values use the same formula as this calculator (BMI 18.5–24.9 kg/m²). They are general ranges, not a diagnosis or medical advice.

Height	Healthy weight range (men and women)
150 cm	41.6 – 56.0 kg
160 cm	47.4 – 63.7 kg
170 cm	53.5 – 72.0 kg
180 cm	59.9 – 80.7 kg
190 cm	66.8 – 89.9 kg

Common use cases

Checking your own weight against a healthy range.
Tracking weight change over time alongside a fitness plan.
A quick screening measure used in clinics and health checks.
Estimating a target healthy weight for your height.

Pro tips

BMI does not measure body fat, so it can mislead for very muscular people.
Measure your height and weight consistently for the most reliable result.
Pair BMI with a waist measurement for a fuller picture.
Adult categories do not apply to children, pregnancy or serious athletes.

BMI categories

BMI	Category
Below 18.5	Underweight
18.5 – 24.9	Healthy / normal
25.0 – 29.9	Overweight
30.0 and above	Obese

How BMI is calculated

BMI = weight (kg) ÷ height (m)²

For the imperial calculator, weight in pounds and height in feet/inches are converted to metric automatically.

BMI Calculator FAQs

What is a healthy BMI?

For most adults, a BMI between 18.5 and 24.9 is considered healthy; 25-29.9 is overweight, and 30 or above is obese.

How is BMI calculated?

BMI = weight in kilograms divided by height in metres squared (kg/m²). Imperial inputs are converted to metric automatically.

Is BMI the same for men and women?

The formula and adult categories are the same for men and women, though the number does not reflect sex-based differences in body composition.

What BMI is considered obese?

A BMI of 30 or above is classified as obese. 25-29.9 is overweight, and 18.5-24.9 is healthy.

Is BMI accurate for athletes and muscular people?

BMI does not tell muscle from fat, so it can overestimate body fat in muscular people. It is a screening tool, not a measure of physique.

What is a healthy weight for my height?

The calculator shows a healthy weight range for the height you enter. For 170 cm, that is roughly 53.5-72 kg.

Does BMI change with age?

The adult formula stays the same, but body composition shifts with age, so BMI is best used alongside other health indicators as you get older.

Is BMI used for children?

For children and teens, BMI uses age- and sex-specific percentiles rather than the fixed adult categories.

Is BMI a diagnosis?

No. BMI is a screening measure only. It does not account for muscle mass, age or body composition, and it is not a medical diagnosis.