Health · Popular

BMI Calculator

A clean, accurate BMI calculator with metric and imperial units, healthy weight ranges, and a visual category indicator based on WHO standards.

Weight kg

Height cm

Your BMI

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22.9

Within the healthy weight range for your height.

15 18.5 25 30 35 40

Healthy range

—

For your height

To reach normal

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Disclaimer. BMI is a screening number, not a medical diagnosis. Speak with a qualified healthcare provider before making decisions about your health, especially if your BMI is outside the normal range.

Method

How this calculator works

BMI compares weight to height squared. The squared height accounts for the fact that taller people have more total mass even at the same body composition.

Metric:    BMI = weight(kg) / height(m)²
Imperial:  BMI = (weight(lb) / height(in)²) × 703

Choose your unit system — metric (kg, cm) or imperial (lb, in).
Enter your current weight and height.
The calculator squares your height and divides weight by it (multiplied by 703 for imperial).
Your BMI value is matched against WHO categories: <18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, ≥30 obese.
The healthy weight range (BMI 18.5–24.9) for your height is computed in reverse so you know the target.

Examples

Worked examples

Real numbers, end-to-end results.

70 kg · 175 cm

BMI 22.9 · Normal

Healthy range: 56.7 – 76.3 kg.

154 lb · 69 in

BMI 22.7 · Normal

Same person, imperial units — the result is essentially identical.

90 kg · 170 cm

BMI 31.1 · Obese

About 17 kg above the upper end of the healthy range.

Use cases

When to use it

Quick screening of weight status during routine self-check-ins.
Identifying a healthy weight target for your height.
Tracking weight changes against a clear numerical reference.
Comparing body composition trends over time alongside other markers.

FAQ

Frequently asked questions

What is BMI and what does it actually measure?

BMI (Body Mass Index) is a single number that estimates body fat based on weight and height. It is a screening tool — not a diagnosis. Two people with the same BMI can have very different body compositions.

What are the BMI categories?

Below 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is obese. These ranges come from the World Health Organization.

Is BMI accurate for athletes or muscular people?

Not always. Muscle weighs more than fat, so very muscular people can register as overweight on BMI without carrying excess fat. Use it alongside other measurements like waist-to-hip ratio.

Does BMI work the same for children?

No. Children and teens use age- and sex-specific BMI percentile charts because their bodies are still developing. This calculator is for adults 18+.

What is the formula?

For metric: BMI = weight (kg) ÷ height² (m²). For imperial: BMI = (weight (lb) ÷ height² (in²)) × 703.