BMI Calculator – Body Mass Index

Knowing just your weight is like looking at a single puzzle piece. A tall, lean man can easily weigh more than a shorter, rounder woman. To see the full picture, you need the Body Mass Index (BMI). It's a smart measurement that connects your height and weight into one easy-to-understand number. Our BMI calculator helps you get that number instantly, showing whether your weight is healthy, too low, or too high.

How to Calculate Your Body Mass Index Manually

The BMI formula is straightforward. Just two steps:

1. Take your weight in kilograms and divide it by your height in meters.
2. Take that result and divide it by your height (in meters) again.

BMI = weight (kg) / height (m)²

For example, if you weigh 70 kg and are 1.75 m tall, your calculation is: 70 / (1.75 * 1.75) = 22.86.

What Does Your Number Mean? The BMI Categories

Your result will fall into one of five standard categories. For clarity, we've put them in a table below.

Frequently Asked Questions (FAQ)

Does a "Normal" BMI depend on age?

For adults (18 years and older), the healthy BMI range (18.5–24.9) is universal and does not change with age. For children and teens, age and sex-specific percentile charts are used.

I'm a 165-pound man who is 5'11". What's my BMI? Does gender affect it?

Let's calculate. First, convert to metric: 165 lbs ≈ 75 kg, and 5'11" ≈ 1.8 meters.

BMI = 75 / (1.8)² = 75 / 3.24 ≈ 23.15

A result of 23.15 falls into the normal or healthy weight category. Here's the key: the BMI formula itself is gender-neutral; the same ranges apply to both men and women.

What exactly is BMI Prime and why is it useful?

BMI Prime is simply your BMI divided by 25 (the upper limit of the normal range). If your result is greater than 1, you're above the healthy weight threshold. It's the quickest way to gauge your status. For example, a BMI Prime of 1.2 means your weight is 20% above the top of the normal range.