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BMI Calculator Guide
Body Mass Index is a quick screening number that relates your weight to your height. This calculator gives your BMI, the category it falls in, and the weight range considered healthy for your height.
BMI = weight (kg) ÷ height (m)². In imperial units, BMI = 703 × weight (lb) ÷ height (in)².
What Is a Healthy BMI?
The standard categories are: under 18.5 is underweight, 18.5–24.9 is a healthy weight, 25–29.9 is overweight, and 30 or above is in the obese range. These are population guidelines, not a diagnosis.
BMI Categories (Adults)
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
What BMI Doesn't Tell You
BMI is a useful screen but a blunt one. It doesn't distinguish muscle from fat, so very muscular people can read as "overweight," and it doesn't reflect where fat is carried or overall fitness. It's a starting point, not the whole picture — a doctor can interpret it alongside other measures.
Worked Example
Someone 5 ft 9 in (1.75 m) weighing 160 lb (72.6 kg): BMI = 72.6 ÷ 1.75² = 23.7, which falls in the healthy range.
This is a general screening estimate for information only — not a diagnosis or medical advice. Individual health depends on many factors; talk to a healthcare professional for guidance specific to you.
For more context, pair BMI with our Body Fat Calculator and TDEE Calculator.
Frequently Asked Questions
What is a healthy BMI?
A BMI between 18.5 and 24.9 is considered a healthy weight for most adults.
How do I calculate BMI?
Divide your weight in kilograms by your height in metres squared, or multiply 703 times your weight in pounds divided by height in inches squared.
Is BMI accurate?
It's a useful screening tool but doesn't separate muscle from fat, so athletes and very muscular people may read high despite being healthy.
Does BMI differ for men and women?
The adult BMI formula and categories are the same for men and women, though body composition at a given BMI can differ.
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