100% Free Online Web Tool

BMI Calculator

Body Mass Index calculator

Health Calculator

BMI Calculator

Calculate your Body Mass Index (BMI) instantly. Check if your weight is healthy for your height.

BMI Categories

UnderweightBelow 18.5
Normal18.5 - 24.9
Overweight25 - 29.9
Obese30 and above

Key Features & Highlights

WHO Standard Formula

Uses the internationally recognized BMI formula (weight/height²) endorsed by World Health Organization.

Metric & Imperial

Switch between kg/cm and lbs/inches with a single click. Perfect for any country's measurement system.

Category Classification

Instantly know if you're underweight, normal, overweight, or obese with clear category labels.

Health Insights

Get personalized ideal weight range based on your height for a healthy BMI (18.5-24.9).

100% Private

No data sent to servers. All BMI calculations happen locally in your browser.

Works Everywhere

Responsive design works on any device - mobile, tablet, or desktop instantly.

How to Use BMI Calculator

1

Choose Unit System

Select Metric (kg/cm) or Imperial (lbs/inches) based on your preference.

2

Enter Your Weight

Type your current weight in kilograms or pounds - accurate to nearest 0.1.

3

Enter Your Height

Input your height in centimeters or feet/inches for precise calculation.

4

View BMI Result

See your BMI value, category (normal/overweight etc), and ideal weight range instantly.

Frequently Asked Questions

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is considered healthy for most adults. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese.

Is BMI accurate for athletes?

BMI may overestimate body fat in athletes and muscular individuals since muscle weighs more than fat. Athletes should use body fat percentage instead.

How is BMI calculated?

BMI = weight (kg) / height² (m²). For imperial: BMI = (weight in lbs × 703) / height² (inches²). Our tool handles both formulas automatically.

Does BMI work for children?

BMI for children uses percentiles based on age and gender, which differ from adult calculations. This tool is designed for adults 18+.

Should I use BMI or body fat percentage?

BMI is a quick screening tool. Body fat percentage is more accurate for fitness assessment. Both together give the best health picture.

Why does my BMI change with age?

Muscle mass typically decreases with age, so the same BMI can mean different body compositions. Combine BMI with waist measurements for better insights.