BMI Calculator

Work out body mass index from weight in kilograms and height in centimetres, and see which standard category the value falls in.

Open in the full calculator → — with every other tool, the AI tutor and PNG export.

How it calculates

BMI = weight (kg) ÷ height (m)²
Below 18.5 underweight · 18.5–24.9 normal · 25–29.9 overweight · 30 and above obese

Worked example

Weight 70 kg, height 175 cm: 70 ÷ 1.75² = 70 ÷ 3.0625 = 22.9, inside the 18.5–24.9 range.

From the Knowledge Base

A person weighs 62 kg and is 1.70 m tall.

Step 1 — square the height. 1.70² = 1.70 × 1.70 = 2.89 m²
Step 2 — divide. 62 ÷ 2.89 = 21.5 kg/m²

Notice how few significant figures the data supports: a weight given as 62 kg has 2, so quoting 21.4532... would be dishonest precision.

Quoted from BMI Formula — What It Does and Does Not Tell You.

From the Knowledge Base

85 kg, height 1.62 m.

1.62² = 2.6244 m²
85 ÷ 2.6244 = 32.4 kg/m²

Quoted from BMI Formula — What It Does and Does Not Tell You.

Learn the method

About this converter

One of the unit converters in the Chemistry Calculator Suite, alongside its chemistry, physics and maths tools. Nothing is behind a login and no value you type is sent anywhere — the conversion runs in your own browser.

The BMI converter above is the live tool — it converts right here on the page. The link under it opens the full suite with this set already selected.

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