BMI Calculator Check Your Body Mass Index Instantly
Enter measurements and press Calculate.
Use the Body Calculator BMI tool to check your Body Mass Index quickly and understand whether your weight is in a healthy range. Enter your height and weight, choose your unit system, and get a clear explanation of your result.
Table of Contents
Enter Your Details
You can switch between Metric, US, and Other Units depending on your preference.
- Age
- Gender
- Height (cm, m, ft/in)
- Weight (kg, lbs, stones)
Click Calculate to see your BMI, category, and recommended healthy weight range.
Your BMI Result
- BMI Value (example: 20.1)
- Category (Underweight, Healthy, Overweight, or Obese)
- Healthy BMI Range (18.5 to 24.9)
- Recommended Weight Range for Your Height
- BMI Prime
- Ponderal Index
BMI Categories
| Category | BMI Range | Meaning |
|---|---|---|
| Severe Thinness | Under 16 | Very low weight |
| Moderate Thinness | 16–17 | Below recommended weight |
| Mild Thinness | 17–18.5 | Slightly low weight |
| Healthy Weight | 18.5–24.9 | Ideal range for most adults |
| Overweight | 25–29.9 | Higher than ideal weight |
| Obese Class I | 30–34.9 | High body fat |
| Obese Class II | 35–39.9 | Very high body fat |
| Obese Class III | 40+ | Extreme obesity |
BMI Formulas
Metric Formula
BMI = weight (kg) ÷ height (m)²
US Formula
BMI = (weight (lbs) × 703) ÷ height (in)²
Other Units
The calculator adjusts automatically when using stones, feet, or inches.
BMI Chart
- Underweight: less than 18.5
- Healthy: 18.5–24.9
- Overweight: 25–29.9
- Obesity: 30+
What BMI Is Considered Healthy?
For adults, a BMI between 18.5 and 24.9 is widely considered healthy.
BMI for Children & Teens (2–20 years)
BMI for children and teens works differently because growth, puberty and age affect weight and height changes.
Child BMI Percentile Table
| Category | Percentile Range |
|---|---|
| Underweight | Below 5th percentile |
| Healthy | 5th–85th percentile |
| Overweight | 85th–95th percentile |
| Obese | Above 95th percentile |
BMI Prime Section
BMI Prime = your BMI ÷ 25
| BMI Prime Range | Meaning |
|---|---|
| Under 0.74 | Underweight |
| 0.74–1.0 | Healthy |
| Over 1.0 | Overweight |
| Over 1.2 | Severe obesity |
Body Fat Percentage vs BMI
| Factor | BMI | Body Fat % |
|---|---|---|
| Measures | Weight/Height | Fat in body |
| Athletes | Often misclassified | Accurate |
| Best for | General population | Fitness and health |
Waist to Height Ratio (WHtR)
WHtR = waist (cm) ÷ height (cm)
- Under 0.4 = underweight
- 0.41–0.49 = healthy
- 0.50–0.59 = overweight
- 0.60+ = high risk
Waist Circumference Health Risk Guide
- Men: Over 102 cm = high risk
- Women: Over 88 cm = high risk
Frequently Asked Questions
What is BMI?
BMI stands for Body Mass Index.
Is BMI accurate?
BMI does not measure muscle mass or fat distribution.
Does BMI change with age?
The formula stays the same, but older adults tend to have more body fat.
Should children use this calculator?
No. Children and teens use percentiles.