BMI Calculator
Calculate your Body Mass Index (BMI) from height and weight, in metric or imperial units, with your weight category.
Normal
A BMI of 23.6 sits well inside the normal range (18.5–24.9).
- CategoryNormal weight
BMI ranges: Underweight <18.5 · Normal 18.5–24.9 · Overweight 25–29.9 · Obese ≥30. BMI doesn't account for muscle mass — the Body Fat Calculator is more precise for athletes.
ƒShow your work
BMI = weight(kg) / height(m)²
- 1Weight = 72.6 kg, Height = 1.75 m
- 2BMI = 72.6 / 1.75² = 23.6
About the BMI Calculator
Body Mass Index is a ratio of weight to height, nothing more — it was never designed to measure body fat directly, and it can't tell the difference between someone carrying extra fat and someone carrying extra muscle. What it's actually good at is flagging, cheaply and instantly, whether a weight is in a range associated with higher health risk across a large population. For any one individual, it's a starting point for a conversation, not a diagnosis.
Doctors' offices use it as a quick intake screen, insurers use it in actuarial models, and most people use it simply to see where they land against the standard categories before digging deeper into things like body fat percentage or waist measurements. It's popular precisely because it only needs two numbers you already know.
A quick reminder before the number: this tool is for general information, not a medical assessment — if you have concerns about your weight or health, a doctor who can examine you is a far better judge than any formula. Everything you type here calculates instantly in your browser and is never sent anywhere, so there's no account needed to check a number you might feel sensitive about.
How it’s calculated
BMI = weight in kilograms ÷ (height in meters)². The formula is often credited to 19th-century statistician Adolphe Quetelet, who was studying population averages, not individual health — which is part of why it holds up better as a population screening tool than as a precise personal metric.
In imperial units the same ratio is usually written as weight(lb) × 703 ÷ height(in)² — the 703 is just a unit-conversion constant so the result lands on the same scale as the metric version; it isn't a different formula.
Frequently asked questions
What is a healthy BMI range?
For most adults, 18.5–24.9 is classified as normal weight, under 18.5 as underweight, 25–29.9 as overweight, and 30+ as obese. These bands are population guidelines, not hard individual cutoffs.
Is BMI accurate for athletes or muscular people?
Not really — muscle is denser than fat, so a lean, muscular person can post a BMI in the "overweight" range despite having low body fat. The Body Fat Calculator or a simple waist measurement gives a more honest picture for anyone carrying significant muscle.
Does BMI account for age or sex?
No — the standard adult BMI formula and its category cutoffs are the same regardless of age or sex, which is one of its best-known limitations, since body composition naturally differs between men and women and shifts with age.
Is BMI accurate for children or teenagers?
No, this calculator isn't meant for kids — pediatric BMI is plotted against age- and sex-specific growth percentile charts, not the fixed adult categories used here.
What should I check instead of, or alongside, BMI?
Waist circumference, body fat percentage, and how your clothes fit over time all tell you something BMI can't. None of them are perfect alone, but together they paint a fuller picture than any single number.
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