BMI & Body Fat Calculator

Q: What is BMI and how is it calculated?

Body Mass Index (BMI) is calculated by dividing your weight in kilograms by the square of your height in metres (BMI = kg/m²). In imperial units, the formula is (weight in lbs ÷ height in inches²) × 703. It gives a single number used to broadly classify weight status.

Q: What is a healthy BMI range?

The World Health Organisation (WHO) defines a healthy BMI as 18.5 to 24.9. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or above is classified as obese. These thresholds may differ slightly for certain ethnic populations.

Q: Is BMI accurate for everyone?

BMI is a useful population-level screening tool but has limitations for individuals. It doesn't distinguish between muscle and fat — a very muscular athlete may have a "high" BMI despite low body fat. It's also less reliable for children, the elderly, and pregnant women.

Q: What is the BMI formula?

Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = (weight (lbs) ÷ height (inches)²) × 703. For example, a person who is 70 kg and 1.75 m tall has a BMI of 70 ÷ (1.75²) = 70 ÷ 3.0625 = 22.9.

Q: What should I do if my BMI is outside the healthy range?

BMI is a screening indicator only, not a medical diagnosis. If your BMI falls outside 18.5–24.9, speak to your GP or a healthcare professional who can assess your overall health using additional measurements like waist circumference, blood pressure, and blood tests.

Our free BMI and body fat calculator gives you two key health metrics in one place. The BMI calculator computes your Body Mass Index using metric (kg/cm) or imperial (lbs/ft) measurements. The body fat calculator uses the U.S. Navy Method to estimate your body fat percentage using simple measurements. Both are screening tools — always consult a healthcare professional for medical advice.

Enter Your Measurements

Height (cm)

Weight (kg)

Your BMI

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Underweight
<18.5Normal
18.5–24.9Overweight
25–29.9Obese
30+

BMI Score

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❓ Frequently Asked Questions

What is BMI and how is it calculated? ▼

Body Mass Index (BMI) is calculated by dividing your weight in kilograms by the square of your height in metres (BMI = kg/m²). In imperial units, the formula is (weight in lbs ÷ height in inches²) × 703. It gives a single number used to broadly classify weight status.

What is a healthy BMI range? ▼

The World Health Organisation (WHO) defines a healthy BMI as 18.5 to 24.9. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or above is classified as obese. These thresholds may differ slightly for certain ethnic populations.

Is BMI accurate for everyone? ▼

BMI is a useful population-level screening tool but has limitations for individuals. It doesn't distinguish between muscle and fat — a very muscular athlete may have a "high" BMI despite low body fat. It's also less reliable for children, the elderly, and pregnant women.

What is the BMI formula? ▼

Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = (weight (lbs) ÷ height (inches)²) × 703. For example, a person who is 70 kg and 1.75 m tall has a BMI of 70 ÷ (1.75²) = 70 ÷ 3.0625 = 22.9.

What should I do if my BMI is outside the healthy range? ▼

BMI is a screening indicator only, not a medical diagnosis. If your BMI falls outside 18.5–24.9, speak to your GP or a healthcare professional who can assess your overall health using additional measurements like waist circumference, blood pressure, and blood tests.