BMI Calculator
Calculate your BMI (Body Mass Index) from height and weight, with ideal weight range and health advice
How to Use BMI Calculator
1
Select unit system (Metric or Imperial)
2
Enter your height (cm or ft・in)
3
Enter your weight (kg or lbs)
4
Click 'Calculate BMI' button
5
Review your BMI value, category, ideal weight range, and health advice
6
Use Reset button to start a new calculation
Key Features
Support for both Metric and Imperial unit systems
Real-time input validation with error messages
Automatic BMI calculation and category classification
Ideal weight range calculation based on BMI 18.5-25
Personalized health advice based on BMI category
Detailed statistics display (height, weight, BMI, ideal weight range)
Color-coded BMI display (underweight: blue, normal: green, overweight: yellow, obese: red)
Body Information
Range: 50-300cm
Frequently Asked Questions (FAQ)
BMI (Body Mass Index) is an internationally recognized measure of body fat based on height and weight. It's calculated as weight(kg) ÷ height(m)² and is recommended by the World Health Organization (WHO) as a standard indicator.
This tool categorizes BMI with color coding: Under 18.5 (underweight, blue), 18.5-24.9 (normal weight, green), 25-29.9 (overweight, yellow), and 30+ (obese, red). BMI 22 is considered optimal with the lowest health risks.
Yes, you can switch between Metric (cm・kg) and Imperial (ft・in・lbs) unit systems using the unit selector. When you change units, the input fields automatically update, and results are displayed in your selected system.
When using Imperial units, enter height in two separate fields: feet (0-8) on the left and inches (0-11.9) on the right. For example, for 5 feet 9 inches, enter '5' in the feet field and '9' in the inches field.
The ideal weight range uses BMI values of 18.5-25 with the formula 'height(m)² × BMI'. Lower bound is height² × 18.5, upper bound is height² × 25. For Imperial units, the result is automatically converted to pounds.
Based on your BMI category, the tool provides specific advice: underweight suggests nutritional improvement, normal weight recommends maintaining current habits, overweight suggests dietary changes and exercise, while obese category recommends consulting healthcare professionals.
The statistics section displays detailed calculation information including your entered height and weight, calculated BMI value, body category classification, and ideal weight range (minimum and maximum). All values are shown in your selected unit system.
For safety and accuracy, height must be between 50-300cm (approximately 1.6-9.8ft) and weight between 1-500kg (approximately 2-1100lbs). Inches must be 0-11 (since 12 inches = 1 foot). Error messages appear for values outside these ranges.
BMI doesn't account for muscle mass, bone density, or body composition. It may overestimate body fat in muscular individuals (athletes) and underestimate it in older adults or those with lower muscle mass. Use this tool as a general reference alongside other health indicators.
A 'Reset' button appears when you've entered values or when results are displayed. Click this button to clear all input values and calculation results, allowing you to start a new calculation from scratch.