About this tool
Calculate Body Mass Index from height and weight.
Body Mass Index (BMI) is a screening measure that uses height and weight to estimate whether a person is underweight, normal weight, overweight or obese. The raw.tools BMI Calculator supports both metric (cm/kg) and imperial (ft, in, lb) input. Results include your BMI score, WHO category, and the ideal weight range for your height.
Example
Input: Height 175 cm, Weight 70 kg
BMI: 70 ÷ (1.75)² = 22.9 — Normal weight (18.5–24.9)
How to use
- Select metric (cm/kg) or imperial (ft/in/lb) units.
- Enter your height.
- Enter your weight.
- BMI score and category appear instantly.
Features
- Metric (cm/kg) and imperial (ft/in/lb)
- BMI category per WHO classification
- Ideal weight range for your height
- Works offline
- No personal data stored
When to use this
Individuals tracking weight-loss or fitness progress over weeks or months, using BMI as a simple trend indicator.
Fitness coaches recording a starting baseline for new clients before designing a training programme.
Healthcare students practising the WHO BMI classification — calculating BMI from given height and weight values.
App developers testing a BMI calculation they are implementing, by cross-checking their output against a known-correct result.
Frequently Asked Questions
What is a healthy BMI?+
WHO defines healthy BMI as 18.5–24.9. Below 18.5 is underweight; 25–29.9 is overweight; 30+ is obese.
Is BMI accurate?+
BMI is a population-level screening tool, not a clinical diagnosis. It does not account for muscle mass, bone density, or fat distribution. Athletes often have a high BMI despite low body fat.
How is BMI calculated?+
BMI = weight(kg) ÷ height(m)². For example: 70 kg ÷ (1.75 m)² = 22.9.
What is the ideal weight for my height?+
The tool shows the healthy weight range (BMI 18.5–24.9) for your entered height. For example: 175 cm → 56.7–76.3 kg.
Is BMI accurate for athletes?+
BMI does not distinguish between muscle and fat mass. Muscular athletes may show a high BMI despite low body fat. For athletes, body fat percentage is a better metric.
What are the WHO BMI classification ranges?+
Underweight: below 18.5 · Normal weight: 18.5–24.9 · Overweight: 25–29.9 · Obese class I: 30–34.9 · Obese class II: 35–39.9 · Obese class III: 40+.
Does BMI apply to children?+
Standard adult BMI is not used for children. For ages 2–18, BMI-for-age percentile charts are used instead, as healthy ranges vary by age and sex.