ToolWren › BMI

BMI Calculator

Calculate your Body Mass Index from your height and weight, in metric or imperial units, and see which standard category the result falls into.

100% client-side · nothing is uploaded

Loading tool…

How to use the BMI

Choose Metric or Imperial units.
Enter your height and weight.
Your BMI and weight category are shown instantly.
BMI is a general guide — it doesn't distinguish muscle from fat.

Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.

About BMI

What is BMI?

Body Mass Index is a simple ratio of weight to height (kg/m²) used as a quick screening measure for weight categories. It's widely used by health organisations as a first indicator.

The categories

The standard ranges are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30+ obese. This tool labels your result automatically.

Limitations

BMI doesn't distinguish muscle from fat or account for body composition, so very muscular people may read as "overweight". Use it as a general guide, not a diagnosis.

Frequently asked questions

How is BMI calculated?

Metric: weight (kg) ÷ height (m)². Imperial: 703 × weight (lb) ÷ height (in)².

What is a healthy BMI?

A BMI between 18.5 and 24.9 is considered normal for most adults.

Is BMI accurate for everyone?

It's a useful screening tool but doesn't measure body fat directly; athletes and the elderly may need other measures.