How it works
Enter your height, and this calculator computes the minimum and maximum weights that fall within the healthy BMI band (18.5–24.9). Rather than asking "what is my BMI right now?" — which requires your current weight — this tool asks "what weight should I target?" and delivers a realistic span.
The healthy weight range is useful for goal-setting. It tells you the lowest and highest weights at which you'd still be classified as healthy by standard screening criteria. Whether you aim for the lower end, middle, or upper boundary depends on your frame, muscle mass, age, and personal health goals — factors beyond height alone.
The formula
Min weight = 18.5 × Height² ÷ 703 (for US units: pounds and inches) or 18.5 × Height² ÷ 10,000 (for metric: kilograms and centimeters)
Max weight = 24.9 × Height² ÷ 703 (US) or 24.9 × Height² ÷ 10,000 (metric)
These formulas apply the BMI definition — weight divided by height squared — in reverse. By plugging in the boundary BMI values (18.5 and 24.9) and solving for weight, you get the edges of the healthy zone.
Worked example
Suppose you are 5 feet 9 inches tall and want to know your healthy weight target range.
First, convert height to inches:
5 feet 9 inches = (5 × 12) + 9 = 69 inches
Calculate the minimum healthy weight (BMI = 18.5):
Min weight = 18.5 × 69² ÷ 703 = 18.5 × 4,761 ÷ 703 ≈ 125 lb
Calculate the maximum healthy weight (BMI = 24.9):
Max weight = 24.9 × 69² ÷ 703 = 24.9 × 4,761 ÷ 703 ≈ 168 lb
Your healthy weight range at 5'9" is approximately 125–168 pounds — a span of about 43 pounds. This range is what the healthy BMI category looks like for your height. If you currently weigh 190 lb, you'd be above this band; if you weigh 110 lb, you'd be below it. The range itself is neutral — where within it you belong depends on your build, fitness level, and medical history.
Common mistakes
One frequent misunderstanding: people assume the midpoint of the range is the "ideal" weight. In reality, the entire range is equally healthy from a BMI standpoint. A 5'9" person at 130 lb is not better or worse than one at 160 lb; both are in the green zone. Your personal ideal may be higher or lower depending on whether you're athletic, sedentary, or managing a chronic condition.
Another pitfall is confusing this tool with a personalized nutrition or fitness recommendation. This calculator uses one metric (BMI) and one input (height). It ignores age, sex, activity level, genetics, medication, and medical history. This is an estimate, not professional medical advice. If you're planning a major weight change, work with a healthcare provider or registered dietitian who can assess your full picture.
Finally, remember that the healthy range is a screening tool for populations, not a diagnostic instrument for individuals. You can be in the range and unhealthy, or outside it and thriving. Use this number as a starting point for conversation with your doctor, not as a final answer.