Use our free BMI Calculator to calculate your Body Mass Index (BMI) and get an instant evaluation of your weight status based on your height, weight, and age. BMI helps assess whether you’re underweight, at a healthy weight, overweight, or obese.
BMI Calculator
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Calorie Calculator | Body Fat Calculataor | BMR Calculator
BMI Categories (Adults)
| Category | BMI Range (kg/m²) |
|---|---|
| Severe Thinness | < 16.0 |
| Moderate Thinness | 16.0 – 16.9 |
| Mild Thinness | 17.0 – 18.4 |
| Normal Weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity Class I | 30.0 – 34.9 |
| Obesity Class II | 35.0 – 39.9 |
| Obesity Class III | 40.0+ |
What Is a BMI Calculator?
A BMI Calculator is a tool that calculates your Body Mass Index — a number that evaluates your body weight relative to your height. The BMI Calculator categorizes your result to indicate whether you are underweight, normal weight, overweight, or obese.
Although the Calculator doesn’t directly measure body fat, it is a reliable and widely accepted indicator of weight-related health status for most people.
Why Use Our BMI Calculator?
- ✅ 100% Free & Instant BMI Calculation
- ✅ Works with US, Metric, and other units
- ✅ Great for fitness planning and health tracking
- ✅ Includes BMI Prime and Ponderal Index
- ✅ Built-in health interpretation of your BMI result
Whether you’re starting your fitness journey or checking your progress, this Calculator gives you quick insight into your weight category.
BMI Calculator for Children & Teens (Ages 2–20)
For individuals under 20, the Calculator uses CDC BMI-for-age percentiles:
| Category | Percentile Range |
|---|---|
| Underweight | < 5% |
| Healthy Weight | 5% – 85% |
| Risk of Overweight | 85% – 95% |
| Overweight | > 95% |
Health Risks (Overweight)
Using a Calculator can help you identify potential health risks linked to being overweight, including:
- Heart disease and stroke
- High blood pressure
- Type 2 diabetes
- Sleep apnea
- Joint pain and osteoarthritis
- Certain cancers
- Low energy and mental health issues
Health Risks (Underweight)
It also flags risks associated with being underweight, such as:
- Malnutrition or vitamin deficiencies
- Weakened immune system
- Fertility or menstrual issues in women
- Bone loss (osteoporosis)
- Delayed growth in children
- Increased risk of complications during surgery
BMI Prime & Ponderal Index
This Calculator provides extended insights like:
- BMI Prime = BMI ÷ 25 → Gives a ratio against the upper “normal” limit
- Ponderal Index = Better accuracy for very tall or short individuals
These advanced features make our Calculator more than just a basic tool — it’s a complete health screener.
BMI Calculator Formulas
Metric (SI):
BMI = weight (kg) ÷ height² (m²)
Example: 70 ÷ (1.8 × 1.8) = 21.6
US Units:
BMI = 703 × weight (lbs) ÷ height² (in²)
Example: 703 × 160 ÷ 70² = 22.9
Example: 703 × 160 ÷ (70 × 70) = 22.9