BMI Calculator

Calculate your Body Mass Index (BMI) from your height and weight, in metric or imperial units. Get your BMI value along with its standard weight category.

Units

Height (cm)

Weight (kg)

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Why use BMI Calculator?

Body Mass Index (BMI) is a quick way to estimate whether your weight falls in a typical range for your height. This calculator supports both metric (centimeters and kilograms) and imperial (feet, inches, and pounds) units, so you do not have to convert anything by hand. Enter your numbers and the BMI value and weight category update immediately, using the standard formulas: weight in kilograms divided by height in meters squared for metric, or weight in pounds divided by height in inches squared, multiplied by 703, for imperial. BMI is a screening estimate, not a diagnosis. It uses only height and weight, so it cannot distinguish muscle from fat and does not account for age, sex, or frame size, which is why athletes often show a higher BMI than their body fat would suggest. Treat the result as a starting point, alongside a fitness plan or a conversation with a healthcare provider, not a final health verdict. Everything runs in your browser, so your height and weight are never sent anywhere or stored.

Key benefits

Supports both metric and imperial units without manual conversion
Shows the standard BMI weight category alongside your score
Recalculates instantly as you adjust height or weight
Runs entirely in your browser, no signup, no data stored
Free with no limit on how many times you check your BMI

Features

Metric (cm/kg) and imperial (ft/in/lb) input modes
Instant recalculation with no submit button
Standard BMI category labels (underweight, normal weight, overweight, obese)
Result card showing BMI value and category together
Works on desktop and mobile browsers

Popular use cases

A quick screening check before a doctor visit
Tracking BMI changes over time alongside a fitness plan
Filling in a BMI field on a health or insurance form
Comparing metric and imperial readings for the same person

How to use BMI Calculator

1
Choose your units
Select Metric (centimeters and kilograms) or Imperial (feet, inches, and pounds).
2
Enter height and weight
Fill in your height and weight in the selected units.
3
Read your BMI
Your BMI value and weight category appear automatically as soon as both fields are filled in.
4
Adjust and compare
Change any number to see your BMI recalculate instantly, no submit button needed.

Frequently asked questions

How is BMI calculated?

Metric: weight (kg) divided by height (m) squared. Imperial: weight (lb) divided by height (in) squared, multiplied by 703.

Is BMI an accurate measure of health?

BMI is a general screening estimate and does not account for muscle mass, bone density, age, sex, or body composition. It should not replace advice from a healthcare provider.

What are the standard BMI categories?

Underweight: below 18.5. Normal weight: 18.5 to 24.9. Overweight: 25 to 29.9. Obese: 30 and above.

Can I switch between metric and imperial units?

Yes. Use the unit buttons above the form to switch, each mode has its own height and weight fields.

Is my height and weight data saved anywhere?

No. The calculation runs as JavaScript in your browser, nothing you type is uploaded or stored after you close the tab.

Last reviewed: July 2026

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