- Free Health Tool
BMI Calculator
A simple, accurate BMI calculator that estimates your Body Mass Index from height and weight, with full support for metric and imperial units.
Use our BMI calculator to check your Body Mass Index using height and weight, with metric and imperial units.
- Free online BMI calculator for adults, men and women.
What Is a BMI Calculator?
A BMI calculator estimates your Body Mass Index using your height and weight. It helps adults understand whether their weight falls into underweight, healthy weight, overweight, or obesity categories. This online BMI calculator works for men and women and supports metric and imperial units.
How the BMI Calculator Works
Calculate BMI online in four quick steps — no signup, no math, no guesswork.
Choose Your Unit System
Pick metric (kg, cm) or imperial (lbs, inches). The BMI calculator handles both.
Enter Height & Weight
Type in your height and weight — the two values needed to calculate BMI accurately.
Add Age & Gender
Optionally include age and gender for added context — the BMI formula stays the same.
View Your Result
Instantly see your BMI score, category, and healthy weight range for your height.
How to Use This BMI Calculator
Follow these six simple steps to calculate your BMI and read your result with confidence.
Select Units
Choose Metric or Imperial depending on your preferenc
Enter Your Weight
Type your weight in kilograms or pounds.
Enter Your Height
Add your height in centimetres, metres, feet, or inches.
Add Age & Gender
Optional fields for added context — not required for the BMI formula.
Click Calculate BMI
The calculator processes the BMI calculation formula instantly.
Review Your Result
Read your BMI category and healthy weight range for your height.
How Is BMI Calculated?
BMI is calculated using a simple mathematical formula that relates your weight to your height. Here's how it works in both metric and imperial units.
Metric BMI Formula
When using kilograms and metres:
BMI = weight (kg) ÷ height (m)²
Imperial BMI Formula
When using pounds and inches:
BMI = 703 × weight (lbs) ÷ height (in)²
Worked Example
If someone weighs 75 kg and is 1.75 m tall:
BMI = 75 ÷ (1.75 × 1.75) = 24.5
A BMI of 24.5 falls into the healthy weight range for adults.
This is exactly how BMI is calculated by health organisations worldwide. Our calculator runs the same BMI calculation formula automatically — you only need to enter your height and weight.
BMI Categories Explained
BMI results fall into four standard categories for adults aged 18 and over.
Underweight
Below 18.5
Underweight
Below 18.5
Underweight
Below 18.5
Underweight
Below 18.5
Note: BMI is a screening tool, not a medical diagnosis. Always speak to a healthcare professional for personal advice.
BMI Calculator for Men and Women
How the BMI calculator works for both sexes — and what you should know before interpreting your number.
BMI Calculator for Men
- The male BMI calculator uses the exact same formula as the female version.
- Men typically have lower body fat and more lean muscle than women at the same BMI.
- Highly muscular men — bodybuilders, rugby players, strength athletes — often score in the overweight range despite low body fat.
- For most adult men, BMI remains a reliable quick health screening number.
BMI Calculator for Women
- The female BMI calculator uses the standard BMI formula without adjustment.
- Women generally carry more body fat than men at the same BMI — this is normal and healthy.
- Pregnant women should not rely on BMI; pregnancy-specific guidance from a clinician is more appropriate.
- Hormonal changes, menopause, and post-pregnancy recovery can affect body composition independently of BMI.
In short — the BMI calculator for women and the BMI calculator for men use the same formula, but body composition, age, and muscle mass should always be considered alongside the result.
Is a BMI Calculator Accurate?
BMI Is a Screening Tool — Not a Body Fat Measurement
BMI is useful for a quick body weight screening, but it does not measure body fat directly. It may be less accurate for athletes, pregnant individuals, older adults, children, or people with high muscle mass. For a complete picture, combine BMI with waist circumference, body fat percentage, and professional medical advice.
Why Use Our Online BMI Calculator?
Six reasons our BMI calculator stands out from the rest.
Quick BMI Result
Get your Body Mass Index in under five seconds.
Metric & Imperial Support
Calculate BMI in kg and cm or in pounds and inches.
Healthy Weight Range
See the recommended weight range for your height.
PDF Result Download
Save your BMI report as a PDF for future reference.
Built for Men & Women
Simple, accurate, and inclusive for all adult users.
Mobile-Friendly Tool
Use the BMI calculator smoothly on phone, tablet, or desktop.