BMI Calculator - Calculate Your Body Mass Index Free

About BMI Calculator

Body Mass Index (BMI) is a widely used screening tool that estimates body fat based on your height and weight. While it doesn't directly measure body fat percentage, it provides a quick, cost-free way to categorize weight status and assess potential health risks.

BMI Calculator supports multiple unit systems (metric and imperial) and displays your result on a visual gauge so you can immediately see where you fall on the BMI scale.

How to Calculate BMI?

1. Enter your height and select the unit (cm, m, ft, or in).
2. Enter your weight and select the unit (kg, lbs, st, or g).
3. Click Calculate BMI to see your result.
4. Your BMI score and category are displayed, along with a gauge visualization.

BMI Formula

BMI is calculated as:

BMI = Weight (kg) ÷ Height² (m²)

For example, a person who is 170 cm tall and weighs 70 kg has a BMI of: 70 ÷ (1.70 × 1.70) = 24.2 (Normal)

BMI Categories (WHO Standards)

Supported Units

• Height: centimeters (cm), meters (m), feet (ft), inches (in)
• Weight: kilograms (kg), pounds (lbs), stone (st), grams (g)

Limitations of BMI

BMI is a useful screening tool, but it has limitations:

• It doesn't distinguish between muscle mass and fat mass — athletes may have a high BMI despite low body fat.
• It doesn't account for age, sex, or ethnicity differences in body composition.
• It's not a diagnostic tool — always consult a healthcare provider for a full health assessment.

FAQ

What is a healthy BMI?

According to the World Health Organization (WHO), a BMI between 18.5 and 24.9 is considered healthy for most adults.

Is BMI accurate for children?

No. Children have different body compositions as they grow. Use BMI-for-age percentiles (provided by pediatricians) for children and teens.

How often should I check my BMI?

For general monitoring, checking every 3–6 months is sufficient. If you're actively managing your weight, monthly tracking can help you see trends.