Ideal Weight Calculator
Estimate your ideal body weight using four established medical formulas — Devine, Robinson, Miller, and Hamwi — plus the healthy weight range based on BMI, for your height and sex.
Understanding Ideal Weight Formulas
Ideal weight formulas were developed independently by different researchers, decades apart, each using their own reference population and assumptions: Hamwi in 1964, Devine in 1974, and Robinson and Miller both in 1983. All four share the same basic structure — a base weight for someone 5 feet tall, plus a fixed amount added for every inch above that — but use different starting weights and per-inch increments for men and women. Because they don't agree with each other, this calculator shows all four together rather than picking one as the 'correct' answer.
Of the four, the Devine formula has the most practical significance today: pharmacists and physicians use it to calculate a patient's 'ideal body weight,' which is then used to dose certain medications more accurately than dosing by actual body weight would allow. This matters most for people who are significantly overweight or underweight, where actual weight-based dosing could be unsafe — for example, some anesthesia and antibiotic dosages are calculated using Devine's ideal body weight rather than the patient's real weight.
None of these formulas account for muscle mass, frame size, bone density, or where fat is distributed on the body — a very muscular person or someone with a naturally large frame can be perfectly healthy well outside these ranges. They were also developed using adult populations only, so they aren't appropriate for children, teenagers, or anyone whose body composition differs substantially from the original reference groups, such as elite athletes. Treat the results as a general reference point to discuss with a healthcare professional, not a strict target.
Disclaimer: We are not doctors, dietitians, or medical professionals, and nothing on this page constitutes medical advice. Results are estimates provided for general informational purposes only — consult a qualified healthcare professional before making decisions about your health, diet, or exercise routine.
Frequently Asked Questions
About this calculator
How Ideal Weight Formulas Work
All four formulas used in this calculator share the same basic structure: a base weight for someone exactly 5 feet (60 inches) tall, plus a fixed amount added for every inch of height above that. Each formula uses separate coefficients for men and women, reflecting average differences in body composition between the sexes, and each was developed independently, using its own reference population, at a different point between 1964 and 1983. Because they don't fully agree with each other — sometimes differing by several kilograms for the exact same height — this calculator shows all four side by side, along with the weight range implied by a normal BMI (18.5–24.9), rather than presenting a single number as if it were exact.
Devine Formula (1974)
The Devine formula was introduced by Dr. B. J. Devine not as a general wellness guideline but as a quick way for clinicians to estimate a patient's 'ideal body weight' for calculating medication doses — originally for aminoglycoside antibiotics, where dosing by actual body weight can be unsafe for overweight or underweight patients. It remains the formula most widely used in medicine today. The formula is: Men — 50 kg + 2.3 kg for every inch over 5 feet. Women — 45.5 kg + 2.3 kg for every inch over 5 feet.
Worked example: a man who is 5 feet 10 inches tall (70 inches, 10 inches over 5 feet) has a Devine ideal weight of 50 + (2.3 × 10) = 73 kg, which converts to 160.9 lb.
Robinson Formula (1983)
Dr. J. D. Robinson developed this formula as a revision of Devine's, adjusting the base weight and per-inch increment using updated reference data. The formula is: Men — 52 kg + 1.9 kg for every inch over 5 feet. Women — 49 kg + 1.7 kg for every inch over 5 feet.
Worked example: for the same 5-foot-10-inch man used above, the Robinson formula gives 52 + (1.9 × 10) = 71 kg (156.5 lb) — 2 kg lower than the Devine estimate for the identical height, illustrating how much the formulas can disagree even though they share the same basic structure.
Miller Formula (1983)
Developed by Dr. D. R. Miller in the same year as Robinson's revision, this formula uses a higher base weight but a smaller per-inch increment than the others, which tends to produce lower estimates for taller people. The formula is: Men — 56.2 kg + 1.41 kg for every inch over 5 feet. Women — 53.1 kg + 1.36 kg for every inch over 5 feet.
Worked example: for the same 5-foot-10-inch man, the Miller formula gives 56.2 + (1.41 × 10) = 70.3 kg (155.0 lb) — the lowest of the four estimates at this height.
Hamwi Formula (1964)
The oldest of the four, the Hamwi formula was developed by Dr. G. J. Hamwi as a fast bedside method for estimating a diabetic patient's ideal weight, used to help calculate calorie and insulin needs — predating the other three formulas by a decade. The formula is: Men — 48.0 kg + 2.7 kg for every inch over 5 feet. Women — 45.5 kg + 2.2 kg for every inch over 5 feet.
Worked example: for the same 5-foot-10-inch man, the Hamwi formula gives 48.0 + (2.7 × 10) = 75 kg (165.3 lb) — the highest of the four estimates, nearly 5 kg (11 lb) above Miller's result for the exact same height.
Comparing All Four for a 5'6" Woman
Applying the same four formulas to a woman who is 5 feet 6 inches tall (66 inches, 6 inches over 5 feet) shows a similar spread: Devine gives 59.3 kg (130.7 lb), Robinson 59.2 kg (130.5 lb), Miller 61.3 kg (135.1 lb), and Hamwi 58.7 kg (129.4 lb) — an average of about 59.6 kg (131.4 lb) across all four, comfortably inside the BMI-based healthy range of 52.0–70.0 kg (114.6–154.3 lb) for that height. The gap between the highest (Miller) and lowest (Hamwi) estimate is about 2.6 kg (5.6 lb) — a useful reminder that these four numbers work best together as a general range to discuss with a healthcare professional, not as a single precise target.
- Four established formulas — Calculates ideal weight using the Devine, Robinson, Miller, and Hamwi formulas side by side, rather than presenting a single number as if it were exact.
- BMI-based healthy range included — Also shows the weight range corresponding to a normal BMI (18.5–24.9) for your exact height, for comparison against the four formula-based estimates.
- Sex-specific calculations — Uses separate coefficients for men and women in every formula, reflecting differences in average body composition.
- US and metric units — Enter your height in feet and inches or centimeters, and see results in pounds or kilograms to match.
- Used in real clinical contexts — The Devine formula in particular is still used today by clinicians to calculate safe medication dosing for certain drugs, not just as a general wellness estimate.