BMI Calculator
Go beyond a number. Get your Body Mass Index, ideal weight range, and personalized health insights - instantly.
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cm
BMI is a screening tool, not a diagnostic measure. Consult a healthcare provider for personalized advice.
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Understanding Your BMI
What does your BMI mean?
BMI is a useful starting point - not the whole picture.
Underweight< 18.5
Healthy18.5 – 24.9
Overweight25 – 29.9
Obese≥ 30
BMI doesn't distinguish muscle from fat and doesn't account for where fat is distributed - two factors that significantly affect health risk. Waist circumference, body fat percentage, and other indicators give a fuller picture. BMI is a starting point, not a verdict.
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FAQ
Common questions about BMI
BMI, or Body Mass Index, is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = kg ÷ m². In imperial units, the formula is (weight in lbs × 703) ÷ height in inches². A result of 18.5–24.9 is considered healthy for most adults.
For adults, the CDC and WHO define BMI categories as: Underweight - below 18.5; Healthy weight - 18.5 to 24.9; Overweight - 25 to 29.9; Obesity - 30 and above. Children and teens use age-and-sex-specific percentile charts instead of these fixed cutoffs.
Not entirely. BMI treats muscle and fat the same way, so muscular athletes often score as "overweight" despite low body fat. It also doesn't account for where fat is stored - belly fat carries more cardiovascular risk than hip or thigh fat. Use BMI alongside waist circumference and body fat percentage for a more complete picture.
The most sustainable approach is a modest calorie deficit (300–500 kcal/day below your needs) combined with regular aerobic activity (150+ minutes/week) and strength training. Sleep and stress management also matter - poor sleep raises hunger hormones and makes calorie restriction harder. Small, consistent changes outperform crash diets every time.
Your ideal weight range is the weight that keeps your BMI between 18.5 and 24.9. Use the calculator above - after entering your height, the Insights panel shows your exact range in kg or lbs. Remember, this is a statistical guideline based on population data, not a rigid personal target.
The formula is the same for all sexes, but women typically carry 8–13% more body fat than men at the same BMI due to hormonal and reproductive differences. This means the health implications of a given BMI can vary. Some researchers suggest that sex-specific cutoffs may be more accurate, though the standard WHO ranges remain widely used.
Monthly tracking is a practical cadence if you're actively working toward a health goal. Daily weight fluctuations of 1–2 kg are completely normal - driven by hydration, meals, and digestion - and can feel misleading. Tracking over weeks or months reveals the real trend. The calculator above saves your last 3 readings automatically.
Yes - apps like Lemon Health analyze your habits, nutrition patterns, and activity data to surface specific, actionable changes rather than generic advice. Instead of telling you to "eat less and move more," Lemon identifies the smallest shifts with the highest impact for your lifestyle, making a healthy BMI achievable and sustainable.