Your measurements
Enter your height and weight, then select Calculate My BMI to see your result.
This calculator uses standard adult BMI categories and is for general informational purposes only — not medical advice.
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How does the BMI calculator work?
BMI compares your weight to your height using a simple formula: weight (kg) ÷ height (m)² in metric units, or 703 × weight (lb) ÷ height (in)² in imperial units. Both give the same result — this calculator converts internally so either unit works.
What is BMI?
BMI (Body Mass Index) is a widely used screening measure that places your height-to-weight ratio into one of four standard adult categories, used as a quick population-level indicator, not a diagnosis.
What do BMI categories mean?
Underweight (below 18.5), Healthy Weight (18.5–24.9), Overweight (25.0–29.9), and Obesity (30.0 and above) are standard adult screening ranges used by health organizations to flag when weight relative to height may be worth discussing with a professional — not a personal diagnosis.
BMI vs. body fat percentage
BMI only uses height and weight — it can't distinguish muscle from fat. Two people with identical BMI can have very different body compositions, which is why BMI works better as a population screening tool than an individual measure of fitness.
Why BMI has limitations
BMI doesn't account for muscle mass, bone density, age, sex, or body fat distribution, so it can be less accurate for athletes, older adults, and other groups. It's a useful starting point, not the full picture — see the calorie calculator and macro calculator for more personalized nutrition estimates.
BMI and healthy weight
The weight range shown for the healthy BMI category is a general reference for your height, not a personal target. If you're working toward a weight-loss goal, the calorie deficit calculator can help estimate a daily calorie target.
Frequently asked questions
BMI (Body Mass Index) is a simple screening measure that estimates whether your weight falls into a healthy range for your height, calculated as weight divided by height squared.
In metric units, BMI = weight (kg) ÷ height (m)². In imperial units, BMI = 703 × weight (lb) ÷ height (in)². Both formulas produce the same BMI value for the same person.
For adults, a BMI between 18.5 and 24.9 falls in the standard "Healthy Weight" screening category. Below 18.5 is categorized as underweight, 25.0–29.9 as overweight, and 30.0 or above as obesity.
No. BMI only uses height and weight — it doesn't directly measure body fat, muscle mass, or body composition. Two people with the same BMI can have very different body compositions.
BMI can overestimate body fat in muscular individuals, since muscle weighs more than fat and BMI doesn't distinguish between the two. It's less reliable for very muscular people, athletes, and some other groups.
No. BMI can show a weight range associated with the healthy BMI category for your height, but this is not a personal target or an "ideal weight" — healthy weight varies by individual factors BMI doesn't account for.
No. This calculator provides a general screening estimate for informational purposes only, not medical advice or diagnosis. Consult a qualified healthcare professional for personal health guidance.
Explore more free MacroLeaf tools
BMI is a general screening measure and does not directly measure body fat or account for muscle mass, body composition, age, sex, or individual health conditions. This calculator is for general informational purposes and is not medical advice. Consult a qualified healthcare professional for personal health guidance.