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BMI Calculator

Calculate BMI from height and weight in metric or imperial units.

Calculate BMI from height and weight in metric or imperial units.

Quick start: Choose your unit system — metric (centimeters and kilograms) or imperial (feet/inches and pounds). → Enter your height. In imperial mode you can split it into feet and inches. → Enter your weight in the matching unit.

How to use BMI Calculator

  1. 1

    Choose your unit system — metric (centimeters and kilograms) or imperial (feet/inches and pounds).

  2. 2

    Enter your height. In imperial mode you can split it into feet and inches.

  3. 3

    Enter your weight in the matching unit.

  4. 4

    Read your BMI value and the category it falls into (underweight, normal, overweight, or obese).

  5. 5

    Check the healthy-weight range shown for your height to see your target band.

Real examples of BMI Calculator in action

Metric
Before
Height 175 cm, weight 70 kg
After
BMI 22.9 — normal weight
Imperial
Before
Height 5 ft 9 in, weight 185 lb
After
BMI 27.3 — overweight
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Who is BMI Calculator for?

People tracking a weight-loss or fitness goal who want a simple progress number

Anyone completing a medical, gym, or insurance form that asks for BMI

Patients preparing for a checkup who want a baseline before seeing a clinician

People following a fitness plan written in different units than they normally use

Why use BMI Calculator?

  • Works in both metric (kg/cm) and imperial (lb/in) units, with no manual conversion.
  • Shows the standard WHO category — underweight, normal, overweight, or obese — alongside the raw number.
  • Displays the healthy weight range for your height so you know your target band, not just one figure.
  • Updates instantly as you type, so you can compare a few what-if weights quickly.
  • Runs entirely in your browser — your height and weight are never sent to a server or logged.

Common use cases

  • Track progress toward a weight goal by checking BMI before and after a change.
  • Fill in a health or insurance form that asks for your BMI.
  • Get a quick baseline before a doctor or nutritionist visit.
  • Compare metric and imperial figures when following a plan written in another unit system.

How BMI Calculator compares to alternatives

Honest comparison to other popular options — pick the right tool for the job.

ToolMain limitation
Google search boxReturns a BMI number but not the healthy-weight range or both unit systems together
Calculator.net BMIComprehensive but ad-heavy and slower to load
BMI CalculatorFree, runs in your browser, no sign-up, no watermarks, no file-size limits beyond your device memory.

Limitations & things to know

  • BMI does not distinguish muscle from fat, so it can misclassify athletes and very lean, muscular people
  • It is not designed for children, pregnant people, or the very elderly
  • It is a screening indicator only and is not a medical diagnosis

About BMI Calculator

Body Mass Index (BMI) is the most common quick screen for whether your weight is in a healthy range for your height. This free BMI calculator works in both metric (kilograms and centimeters) and imperial (pounds and feet/inches) units, so you do not have to convert anything by hand. Enter your height and weight and it instantly returns your BMI value, the category it falls into using the standard World Health Organization bands, and the healthy weight range for your height. The WHO categories for adults are: underweight (below 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obese (30 and above). BMI is calculated as weight in kilograms divided by height in meters squared, or 703 times weight in pounds divided by height in inches squared for imperial measurements. It is important to understand what BMI does and does not tell you. Because it relies only on height and weight, it cannot separate muscle from fat. A very muscular athlete may register as overweight despite being lean, while an older adult who has lost muscle may register as normal despite carrying excess fat. BMI also does not consider age, sex, ethnicity, or where fat is stored on the body. For these reasons it works best as a starting point that flags whether a more detailed assessment is worth doing, rather than as a standalone health verdict. Everything is computed locally in your browser, so the height and weight you enter are never transmitted or stored.

Frequently asked questions

BMI = weight (kg) divided by height (m) squared. In imperial units the formula is 703 x weight (lb) / height (in) squared. This tool applies whichever formula matches the units you choose.
The World Health Organization defines under 18.5 as underweight, 18.5 to 24.9 as normal, 25 to 29.9 as overweight, and 30 or above as obese. These bands are for adults aged 20 and over.
Not always. BMI does not distinguish muscle from fat, so very muscular people can show a high BMI while being lean. It also does not account for age, sex, bone density, or fat distribution. Treat it as one screening number, not a diagnosis.
No. The calculation runs in your browser with JavaScript. Nothing you enter is uploaded, saved, or shared.

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<iframe src="https://www.xevontools.com/embed/bmi-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px;" title="BMI Calculator — Xevon Tools"></iframe>
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