How to Calculate BMI: A Complete Guide (2026)

Body Mass Index (BMI) is a simple numerical measure of body weight relative to height. It is widely used by health professionals as a quick screening tool.

The BMI formula

BMI = weight (kg) / height² (m²). For imperial units, multiply by 703 and use pounds and inches.

Healthy BMI ranges

Under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30+ is considered obese.

Limitations of BMI

BMI does not distinguish muscle from fat, so athletes may register as overweight. Always combine BMI with waist circumference and body fat percentage.

How to use the BMI calculator

Enter your height and weight in our free BMI calculator to instantly see your BMI and category.

Recommended free tools

BMI Calculator — Calculate your Body Mass Index instantly. Free BMI calculator with metric and imperial units.
Age Calculator — Calculate your exact age in years, months, days, hours and minutes from your date of birth.
Loan EMI Calculator — Calculate your monthly loan EMI, total interest, and amortization schedule for any loan.
Percentage Calculator — Calculate percentages, percentage change, percentage of a number — fast and accurate.
Tip Calculator — Quickly calculate tip amount and split bills among friends. Free tip calculator.
Password Generator — Generate strong, secure, random passwords. Customize length and character types.