Body Mass Index (BMI) is a measure of body fat based on height and weight. It's used to screen for weight categories that may lead to health problems. BMI = weight ÷ height².

What is a healthy BMI?

A BMI between 18.5 and 24.9 is considered healthy (normal weight). Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese.

Is BMI accurate for everyone?

BMI doesn't distinguish between muscle and fat. Athletes and muscular people may have high BMI but low body fat. It's a screening tool, not a diagnostic. Consult a healthcare provider for comprehensive assessment.

How do I calculate BMI in metric units?

BMI = weight (kg) ÷ height (m)². First convert height from cm to m by dividing by 100. For example, 170 cm = 1.70 m.

How do I calculate BMI in imperial units?

BMI = (weight (lbs) ÷ height (in)²) × 703. The 703 factor converts from imperial to metric equivalent. For example, 154 lbs, 67 in = (154 ÷ 67²) × 703 = 24.1.

What are the BMI categories?

BMI categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese (30+). These categories are used worldwide for health screening.

BMI Calculator

Calculate your Body Mass Index (BMI) to assess your weight category. Enter your height and weight in metric or imperial units to automatically calculate BMI and determine if you're underweight, normal, overweight, or obese.

Calculator

Result

Your BMI: 0.0
Category: -

BMI Categories: Underweight (<18.5) | Normal (18.5-24.9) | Overweight (25-29.9) | Obese (30+)

Formula & Guide

Formula

M

Metric

BMI = kg / m²

Weight in kg, height in meters (convert cm to m)

I

Imperial

BMI = (lbs / in²) × 703

Weight in pounds, height in inches

Formula Variables

W

Weight

Body weight in kg (metric) or lbs (imperial)

H

Height

Body height in meters (metric) or inches (imperial)

BMI

Body Mass Index

Calculated BMI value used to assess weight category

Step-by-Step Scenario

Example Scenario

Weight

70 kg

Height

170 cm

1

Convert Height to Meters

170 cm = 1.70 m

Convert centimeters to meters by dividing by 100

2

Calculate BMI

BMI = 70 ÷ (1.70)²
BMI = 70 ÷ 2.89

BMI = 24.2 (Normal)

Additional Examples

Underweight

Weight: 50 kg

Height: 170 cm

BMI

17.3 (Underweight)

Overweight

Weight: 90 kg

Height: 170 cm

BMI

31.1 (Obese)

Characteristics of BMI

Screening Tool

BMI is a quick screening tool to assess weight-related health risks. Used by healthcare providers worldwide.

Health Categories

BMI categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese (30+).

Dual Units

Supports both metric (kg, cm) and imperial (lbs, inches) units. Switch between units easily.

Health Indicator

High BMI is associated with increased risk of diabetes, heart disease, and other health conditions.

Important Notes

BMI doesn't account for muscle mass or body composition. Athletes and muscular people may have high BMI but low body fat.
BMI is a screening tool, not a diagnostic. Consult a healthcare provider for comprehensive health assessment.
BMI categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese (30+).
For metric: BMI = weight (kg) ÷ height (m)². Convert cm to m by dividing by 100.
For imperial: BMI = (weight (lbs) ÷ height (in)²) × 703. The 703 factor converts from imperial to metric equivalent.

Frequently Asked Questions

Common questions about BMI.