BMI Calculator
Calculate your Body Mass Index (BMI) using your height and weight. Get the WHO category classification (underweight, healthy, overweight, obese) with a color-coded indicator. The tool also shows your healthy weight range for your height and how far you are from it. Supports both metric (cm/kg) and imperial (ft·in/lb) units, plus an Asian-population threshold option with lower obesity cutoffs.
What does this tool do?
The BMI Calculator computes body mass index using the standard formula: weight (kg) / height² (m²). It categorizes results using WHO standards: underweight (<18.5), healthy weight (18.5-24.9), overweight (25-29.9), obese (≥30). The tool also calculates your healthy weight range — the weight you'd need to be for a BMI of 18.5 to 24.9 at your height. An Asian-population mode uses lower thresholds (overweight ≥23, obese ≥27.5) based on research showing health risks occur at lower BMIs for many Asian populations. The result includes personalized feedback on your category.
How it works
BMI is calculated by dividing weight in kilograms by the square of height in meters. For imperial units: weight (lb) × 703 / height² (inches). The WHO categories are applied after calculation. Healthy weight range is computed by rearranging the BMI formula: min healthy weight = 18.5 × height², max healthy weight = 24.9 × height². The difference from nearest healthy weight shows how much you'd need to gain or lose. Asian thresholds are based on WHO Western Pacific Region recommendations. The color indicator provides visual feedback: blue for underweight, green for healthy, yellow for overweight, orange for obese class I, red for obese class II+.
Features
- Metric (cm/kg) or imperial (ft·in/lb) input
- WHO BMI categories with colour-coded indicator
- Healthy weight range for your height
- Difference from nearest healthy weight
- Asian-population threshold option (lower cutoffs)
- Children/teen note (consult pediatric charts)
- Personalized category description
How to use
- 1
Select units
Choose Metric for cm/kg or Imperial for feet/inches and pounds.
- 2
Enter height and weight
Input your current measurements. For imperial height, enter feet and inches separately.
- 3
Review results
See your BMI value, WHO category with color indicator, healthy weight range, and how much you'd need to change to reach healthy range.
- 4
Consider Asian thresholds
If of Asian descent, enable Asian thresholds to see category using lower cutoffs based on population-specific health risk research.
Common use cases
Health screening
Quick initial assessment of weight status as part of general health awareness and wellness tracking.
Weight goal planning
Understand your healthy weight range and set realistic targets based on how far you are from it.
Fitness progress tracking
Monitor BMI changes over time as you pursue fitness goals, though note BMI is just one of many health indicators.
Pre-medical appointment prep
Calculate your BMI before doctor visits so you're prepared to discuss your measurements intelligently.
Tips & best practices
- BMI is a screening tool, not a diagnostic of body fatness or health. Muscular individuals may have 'overweight' BMI with low body fat
- Waist circumference is often a better health predictor than BMI alone — consider measuring waist-to-height ratio too
- Healthy BMI ranges differ for Asian populations due to different body composition — use the Asian threshold option if applicable
- BMI is not appropriate for children — use age and sex-specific percentile charts for kids and teens