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BMI Calculator
Calculate your body mass index from height and weight, see your WHO category, and turn the number into a daily calorie plan.
Your BMI
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BMI is a screening tool, not a diagnosis. Athletes and older adults may need a different lens — use it with TDEE and meal tracking.
A BMI calculator turns two simple measurements — height and weight — into a single number that health organisations use to screen for underweight, healthy weight, overweight, and obesity. It is not a perfect measure of body fat, but it is the most searched, most understood starting point for anyone who wants a clearer picture of their weight relative to height.
How BMI is calculated
Body mass index equals weight in kilograms divided by height in metres squared (kg/m²). In imperial units the same formula uses pounds and inches with a conversion factor. Categories follow the World Health Organization cut-offs: below 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, and 30+ obese. This free BMI calculator runs entirely in your browser — nothing is stored unless you create an account and save a goal.
What to do after you know your BMI
A number alone does not change anything. If you want to lose weight, pair your BMI with a TDEE calculator to find maintenance calories, then use a modest calorie deficit and track real meals with the photo calorie tracker. If you are underweight and want to gain, flip the same loop into a surplus — see how to gain weight. For a full plan, read how to lose weight without crash dieting.
Limits of BMI (and why it still helps)
BMI does not distinguish muscle from fat, so a muscular lifter can score “overweight” while being metabolically healthy. It also says nothing about waist fat, blood markers, or fitness. Still, for the average adult it is a fast, free signal that correlates with health risk at population level — and it is the keyword millions of people search when they are ready to act. Use it as a door, not a verdict.
Frequently asked questions
- What is a healthy BMI?
- For most adults, a BMI between 18.5 and 24.9 is classed as a healthy weight by the WHO. Values below 18.5 are underweight; 25–29.9 overweight; 30 and above obese.
- Is this BMI calculator free?
- Yes. You can calculate BMI with no account and no email. Creating a free account lets you save height, weight, and a daily calorie goal.
- How accurate is BMI?
- BMI is a screening estimate based on height and weight only. It can misclassify muscular people and does not measure body fat directly. Combine it with waist size, strength, and how you feel.
- Can I use BMI to set a calorie goal?
- BMI tells you where you sit on the scale; TDEE tells you how many calories you burn. Use both: check BMI here, then open the TDEE calculator and save a goal to track meals against your target.
- Does BMI work the same for men and women?
- The WHO BMI formula and cut-offs are the same for adult men and women. Targets for fat loss or muscle gain still differ by sex, age, and activity — that is why the TDEE step matters.