Find your Body Mass Index in seconds. This free BMI calculator works in metric or imperial units and shows your BMI, weight category and the healthy weight range for your height — a quick screening tool, not a diagnosis.
Your measurements
cm
kg
ftin
lb
Your BMI
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Enter your height and weight
Category
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Healthy BMI range
18.5–24.9
Healthy weight for height
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Units
Metric
BMI is a general screening tool, not a diagnosis. It doesn’t distinguish muscle from fat. Talk to a healthcare professional about what’s healthy for you.
Use this free BMI calculator to find your Body Mass Index from your height and weight. Enter your measurements in metric or imperial units to see your BMI, weight category and the healthy range for your height.
What this BMI calculator shows you
A BMI calculator estimates your Body Mass Index — a number that relates your weight to your height. Enter your height and weight, and it returns your BMI, the standard weight category it falls in, and the healthy weight range for your height. BMI is a quick screening tool used worldwide.
Keep in mind: BMI is a general screening measure, not a diagnosis. It doesn’t distinguish muscle from fat or account for age, sex, ethnicity or body composition, so a very muscular person can read “overweight.” Treat it as a starting point and talk to a healthcare professional about what’s healthy for you.
How BMI is calculated
BMI = weight (kg) ÷ height (m)²
For someone 175 cm tall weighing 70 kg: 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy range. In imperial units the formula is weight (lb) ÷ height (in)² × 703.
BMI categories
BMI
Category
Below 18.5
Underweight
18.5 – 24.9
Healthy weight
25.0 – 29.9
Overweight
30.0 and above
Obese
These are the standard adult categories used by major health bodies. Children and teens use age- and sex-specific percentiles instead.
How to use the BMI calculator
Choose your units. Metric (cm, kg) or imperial (ft/in, lb).
Enter your height and weight.
Read your result. Your BMI, category and healthy weight range appear instantly.
What BMI doesn’t tell you
Body composition. Muscle weighs more than fat, so athletes can score high.
Fat distribution. Where you carry weight matters for health; BMI ignores it.
Age, sex and ethnicity all affect what’s healthy, beyond a single number.
Overall health — diet, fitness, sleep and bloodwork tell a fuller story.
BMI terms glossary
Term
What it means
BMI
Body Mass Index — weight relative to height.
Healthy range
A BMI of 18.5 to 24.9 for most adults.
Body composition
The proportion of fat, muscle and bone in the body.
Screening tool
A quick check that flags when a closer look may help.
BMI Calculator FAQ
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared.
For 70 kg at 175 cm, that's 70 ÷ (1.75 × 1.75) = 22.9.
In imperial units it's weight (lb) ÷ height (in)² × 703.
What is a healthy BMI?
For most adults, a BMI of 18.5 to 24.9 is considered the healthy range.
Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate?
BMI is a useful population screening tool but has limits for individuals.
It doesn't separate muscle from fat or account for age, sex or body composition,
so very muscular people may score high. Use it alongside other measures and professional advice.
Does BMI work for children?
Not in the same way. Children and teens are assessed using age- and sex-specific BMI percentiles
rather than fixed adult categories, so a pediatric chart or professional should be used.
What should I do about my BMI result?
Treat it as a starting point, not a verdict. If you have questions about your weight or health,
a doctor or registered dietitian can give guidance tailored to you.
Is the BMI calculator free to use?
Yes, this BMI calculator is completely free, needs no sign-up,
and gives instant results directly in your browser.
