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BMI Calculator

100% free — calculate your Body Mass Index (BMI) instantly in metric or imperial units. See your category, a visual scale and your healthy weight range.

kg
cm
Three simple steps

How to calculate your BMI online

Enter your measurements and get your Body Mass Index in seconds.

  1. 1

    Choose your units

    Select Metric (kg and cm) or Imperial (lb and ft/in) — whichever you prefer.

  2. 2

    Enter height & weight

    Type in your measurements. Your BMI updates instantly as you type.

  3. 3

    Read your result

    See your BMI score, WHO category, position on the scale and healthy weight range.

Everything you need

A BMI calculator that works your way

Metric or imperial, instant results, and clear category guidance.

Metric & imperial

Switch between kg/cm and lb/ft/in with one click — no manual conversion needed.

WHO categories

See where you fall: underweight, normal, overweight or obesity (Classes I–III).

Visual BMI scale

A colour-coded scale shows exactly where your BMI sits across all categories.

Healthy weight range

Find the weight range for a healthy BMI (18.5–24.9) at your height.

Instant results

Everything recalculates the moment you change a number — no buttons to press.

100% private

All calculations run locally in your browser. Your data is never uploaded.

Calculate your Body Mass Index (BMI) instantly

Your Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate whether you are in a healthy weight range. This free BMI calculator works for both metric (kilograms and centimetres) and imperial (pounds, feet and inches) measurements, shows your BMI category according to WHO guidelines, and tells you the healthy weight range for your height.

How BMI is calculated

The formula is straightforward: BMI = weight (kg) ÷ height (m)². For example, if you weigh 70 kg and are 175 cm tall (1.75 m), your BMI is 70 ÷ (1.75 × 1.75) = 22.9, which falls in the normal weight range. If you use imperial units, the calculator converts pounds and feet/inches to metric internally before applying the same formula.

BMI categories explained

The World Health Organization classifies adult BMI as follows: under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obesity (subdivided into Classes I, II and III). This calculator displays your category alongside a colour-coded scale so you can see where you stand at a glance.

Limitations of BMI

BMI is a useful screening tool for most adults but it does not directly measure body fat. It may overestimate body fat in muscular athletes and underestimate it in older adults who have lost muscle mass. It is also not intended for pregnant women or children. For personal health decisions, always consult a qualified healthcare professional.

Because everything runs on your device, there's nothing to install and nothing is uploaded. Your measurements stay completely private, and the calculator works even when you're offline. This is one of many free browser tools on Uzetool — explore more tools as we add them.

Disclaimer: This BMI calculator is for informational purposes only and is not medical advice. Always consult a healthcare provider for health-related decisions.

Questions

Frequently asked questions

How is BMI calculated?

BMI = weight (kg) ÷ height (m)². For imperial units, pounds and feet/inches are converted to metric first, then the same formula is applied.

What is a healthy BMI?

For adults, WHO defines a healthy BMI as 18.5 to 24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obesity. This calculator shows your category and healthy weight range.

Can I use pounds and feet instead of kg and cm?

Yes. Switch to Imperial, enter your weight in pounds and height in feet and inches. The calculator converts internally and shows the same BMI result.

Is BMI accurate for everyone?

BMI is a useful screening tool but does not measure body fat directly. It may not suit athletes, older adults, pregnant women or children. Consult a healthcare professional for personal advice.

Is the BMI calculator free and private?

Yes — it's 100% free with no sign-up or limits, and every calculation runs locally in your browser. Your measurements are never uploaded. The tool is supported by unobtrusive ads so it can stay free.