BMI Explained: How to Find Your Healthy Weight Range

By calculatorfc.online Editorial Team · Updated 2026-05-10

What is BMI?

Body Mass Index (BMI) is a simple screening number that relates your weight to your height. It is widely used to categorise underweight, normal, overweight and obese ranges.

The BMI formula

BMI = weight (kg) ÷ height (m)². For example, a person who is 70 kg and 1.75 m tall has a BMI of 70 ÷ (1.75×1.75) = 22.9.

BMI categories

Below 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is in the obese range.

Limits of BMI

BMI does not distinguish muscle from fat and does not account for age, sex or body composition. Athletes may show a high BMI despite low body fat, so treat BMI as a starting point, not a diagnosis.

Using BMI wisely

Combine BMI with waist measurement, activity level and a doctor’s advice for a fuller picture of your health.