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Free BMI Calculator – Calculate Body Mass Index Online

BMI Calculator computes your Body Mass Index (BMI) online for free. Find out if you are underweight, normal, or overweight.

How to Use BMI Calculator

1

Enter Height and Weight

Enter your height (cm or feet/inches) and weight (kg or lbs).

2

Calculate BMI

Click Calculate BMI to see your BMI score instantly.

3

View Health Category

See your BMI category (underweight, normal, overweight, obese) and ideal weight range.

Calculate Your BMI and Healthy Weight Range

The Helperzy BMI Calculator works out your Body Mass Index from your height and weight, then tells you which category you fall into: underweight, normal weight, overweight, or obese. BMI is a quick screening number used worldwide because it needs only two measurements and gives a rough sense of whether your weight is in a healthy range for your height. It also estimates the weight range that would put you in the normal category. The formula is BMI = weight (kg) divided by height (metres) squared. For example, a person who is 1.7 m tall and weighs 65 kg has a BMI of about 22.5. The calculator supports both metric (kg and cm) and imperial (pounds and inches) units, and converts automatically, so you can use whichever measurements you have on hand. It helps for everyday health awareness, fitness goal setting, and tracking changes over time as you lose or gain weight. Standard WHO cut-offs are underweight below 18.5, normal 18.5 to 24.9, overweight 25 to 29.9, and obese 30 or above. Because body composition differs across populations, many health bodies use lower thresholds for people of Asian descent, where overweight begins around 23. It is important to understand what BMI does not measure. It cannot tell muscle from fat, so a muscular athlete may register as overweight while carrying very little fat. It also ignores where fat is stored, age, sex, and bone density, and it is not designed for children, pregnant women, or the elderly without adjustment. Treat your BMI as one simple data point, not a diagnosis. For a fuller picture of your health, combine it with waist measurement, body fat percentage, and how you feel, and speak to a doctor or registered dietitian before making major changes to your diet or exercise routine.

Frequently Asked Questions – BMI Calculator

Enter your height and weight in Helperzy BMI Calculator and click Calculate. Your BMI value and health category — underweight, normal, overweight, or obese — appear instantly, along with the healthy weight range for your height. The calculation runs in your browser, so your measurements are never uploaded or stored.