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Free Fitness Tool
BMI Calculator
Enter your height and weight to find your BMI in seconds. Learn what your number means, and where it falls short.
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Not medical advice: This content, and any calculator results on this site, are for general informational purposes only and are not a substitute for professional medical advice, diagnosis, or treatment. Always talk to a qualified healthcare provider before starting a new diet, exercise routine, or health program.
How It Works
How it's calculated
Your BMI comes from one simple formula. Take your weight in kilograms and divide it by your height in meters, squared. That's it. Doctors picked this formula because it needs only two numbers, yet it still tracks fairly well with body fat across large groups of people. You don't need a lab or special tools. A scale and a tape measure are enough.
How to interpret your result
Once you have your number, compare it to four ranges. Below 18.5 counts as underweight. Between 18.5 and 24.9 sits in the healthy zone. From 25 to 29.9 falls into overweight. Anything at 30 or above is classed as obese. These ranges work well for large populations, but they miss something important: muscle. A rugby player and someone who never exercises can share the same BMI, yet carry very different amounts of fat. Use your BMI as a starting clue, not a final verdict. Pair it with a tape measure around your waist, or a body fat estimate, for a fuller picture.
Frequently Asked Questions
Is BMI accurate for athletes or muscular people?
Not really. Muscle weighs more than fat for the same size, so athletes often score as overweight on the BMI scale despite low body fat. If you train hard and build muscle, check your body fat percentage instead. It tells a more honest story.
Does BMI change with age or gender?
The standard chart uses one set of ranges for all adults. It wasn't built for children, teenagers, or older adults past 65, where a higher number often causes no harm. If you fall in one of these groups, talk to a doctor about what your number really means for you.
My BMI sits outside the healthy range. What now?
Don't panic over one number. Look at the full picture: your energy levels, how your clothes fit, your waist size, and your daily habits. If you're worried, book a chat with your doctor. They can help you set a realistic, healthy target.