Calculate your Body Mass Index instantly and see if your weight is healthy.
What is BMI? Body Mass Index (BMI) is a screening number calculated from your height and weight. A BMI between 18.5 and 24.9 is considered healthy for most adults, while values outside that range may indicate underweight, overweight, or obesity.
Your BMI
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Category
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Healthy weight range for your height
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Tip: calculate first — your result is included when you share.
📚 Related guide: The BMI formula stays the same after 60, but the healthy range shifts — read How to Calculate BMI for Seniors Over 60 before judging your result.
Body Mass Index (BMI) is the world's most widely used screening measure for weight categories. It is calculated by dividing your weight in kilograms by the square of your height in metres. Doctors, fitness coaches and insurance companies all use it as a quick first check of whether someone's weight is in a healthy range for their height.
To use this calculator, pick your preferred units (metric or imperial), enter your height and weight, then press Calculate BMI. You will instantly see your BMI value, your weight category — underweight, normal, overweight or obese — and the healthy weight range for your height, so you know roughly what target to aim for.
The standard adult categories are: below 18.5 is underweight, 18.5 to 24.9 is the normal healthy range, 25 to 29.9 is overweight, and 30 or above is obese. These cut-offs come from the World Health Organization and are the same ones your doctor uses.
Keep in mind that BMI is a screening tool, not a diagnosis. Very muscular people, athletes and pregnant women can get misleading results because BMI cannot tell muscle apart from fat. If your result surprises you, treat it as a prompt to talk to a health professional rather than a final verdict — and pair it with our Calorie Calculator to plan a sensible diet.
Frequently Asked Questions
What is a good BMI for my age?
For adults aged 20 and over, a BMI between 18.5 and 24.9 is considered the healthy range, regardless of age. For children and teens, BMI is interpreted with age-and-gender percentile charts instead of the adult cut-offs.
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For imperial units: BMI = 703 × weight (lbs) ÷ height (inches)². This calculator handles both systems automatically.
Is BMI accurate for muscular people?
Not always. BMI cannot distinguish muscle from fat, so athletes and very muscular people may be classed as overweight despite low body fat. Waist measurement and body-fat percentage give a fuller picture.
What BMI is considered obese?
A BMI of 30 or higher is classified as obese (Class I: 30–34.9, Class II: 35–39.9, Class III: 40+). A BMI of 25–29.9 is classified as overweight.
How often should I check my BMI?
Checking once a month is plenty for most people tracking weight loss or gain. Daily checks fluctuate with water weight and are not meaningful.
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