Ideal Weight by Hamwi, Devine, Robinson and Miller Formulas

Every ideal weight calculator on the internet gives you a single tidy number. This one gives you four because the history of medicine could not agree on one. Between 1964 and 1983, four different research groups published height-to-weight formulas, each using slightly different cohorts and slightly different goals. The Metropolitan Life tables of the 1950s and 60s — the data behind Hamwi — were built for life insurance pricing. Devine was designed to dose medications in hospitals. Robinson and Miller were academic revisions to correct what their authors saw as over-restriction in Devine.

None of these formulas were ever meant to be the single authority on what a person should weigh. Used together, they bracket a realistic range for someone of average muscle mass at a given height. Used alone, any one of them risks steering a lifter toward an unrealistically low target or letting a sedentary adult hide behind a generous one.

Hamwi (1964)

Dr. G. J. Hamwi developed the formula to rapidly dose insulin for diabetic patients. For men: 106 pounds for the first 5 feet of height, plus 6 pounds per inch over. For women: 100 pounds for the first 5 feet, plus 5 pounds per inch over. At 5 foot 10 that returns 166 pounds for a man and 150 pounds for a woman — both numbers sit in the lower third of the modern healthy BMI range. Hamwi is the simplest to compute by hand and the most restrictive of the four, which is why it shows up in weight loss marketing.

Hamwi does not account for frame size. The original paper noted adjusting plus or minus 10% for large or small frame, but the practical definition of frame size (wrist circumference) is rarely used. Use Hamwi only as one of several reference points.

Devine (1974)

B. J. Devine published his formula to calculate safe aminoglycoside antibiotic doses, since fat tissue metabolizes these drugs differently than lean tissue. Men: 50 kg for the first 5 feet, plus 2.3 kg per inch over. Women: 45.5 kg for the first 5 feet, plus 2.3 kg per inch over. Devine is the most widely used formula in clinical practice in the United States because the FDA and the pharmacy profession standardized around it in the 1980s for drug dosing calculations.

Devine is not a weight-loss target — it is a dose-calculation tool. Using it as a body goal is a misapplication. But since it shows up in every medical dosing reference, knowing your Devine weight is useful context when discussing body weight with a clinician.

Robinson (1983)

J. D. Robinson and colleagues at the University of Texas reworked Devine using a larger data set and argued that the base weights were slightly too low. Men: 52 kg plus 1.9 kg per inch over 5 feet. Women: 49 kg plus 1.7 kg per inch over. At 5 foot 10 Robinson returns 171 pounds for a man, about 5 pounds higher than Hamwi, which places the target solidly in the middle of the healthy BMI band.

Robinson is the most neutral of the four — not as restrictive as Hamwi, not as generous as Miller. For an adult with average muscle mass and no history of competitive athletics, Robinson is usually the closest single formula to a reasonable long-term target.

Miller (1983)

D. R. Miller published in the same year as Robinson but used a different data source and arrived at higher baseline weights. Men: 56.2 kg plus 1.41 kg per inch over 5 feet. Women: 53.1 kg plus 1.36 kg per inch over. At 5 foot 10 Miller returns 178 pounds for a man — noticeably higher than the other three, which is why Miller is the most realistic formula for adults who lift weights or carry normal modern adult muscle mass.

Miller also happens to sit closest to the upper end of the BMI healthy range, which matches modern epidemiological data showing lowest all-cause mortality at a BMI of 23–25 rather than the lower end of 18.5–20.

The BMI healthy range as a sanity check

The World Health Organization defines a healthy BMI as 18.5 to 24.9. Multiplying that range by your height squared gives you a target weight band rather than a point. At 5 foot 10 the BMI band is 129 to 173 pounds — a 44-pound range. The classical ideal weight formulas all sit inside this band, with Hamwi at the lower quartile and Miller near the upper quartile. Use the BMI band when frame size or muscle mass matters and a single formula feels arbitrary.

What these formulas miss

None of the four formulas account for muscle mass. A 5-foot-10 powerlifter carrying 195 pounds at 12% body fat is lean and healthy even though every formula tells him his 'ideal' weight is between 166 and 178 pounds. If you are muscular, confirm your number against the lean body mass calculator: your fat mass, not your total weight, is what matters for health outcomes.

The formulas also do not adjust for ethnicity. South Asian adults develop metabolic syndrome at lower BMI than North American Caucasians, and the World Health Organization suggests a healthy BMI ceiling of 22.9 rather than 24.9 for this group. Pacific Islander and sub-Saharan African adults sit at the opposite end: healthy metabolic markers persist at higher BMI. Use the formulas as a reference, not an absolute.

How to use your number

If the gap between your current weight and your averaged ideal weight is large, do not try to close it in one cut. Aim for 10% of starting body weight in the first phase, take a 4-week diet break at the new maintenance, and repeat. A 230-pound adult targeting Miller-weight of 175 pounds is looking at three cut phases over 9–12 months, not one 6-month crash.

Run the numbers, then plug the intermediate target into the calorie deficit and goal weight by date calculators to turn a target weight into a daily intake. The weight number alone does nothing; the daily calorie number that reaches it is what matters.

When the formulas actively mislead

Two groups should not use these formulas as targets: athletes and the elderly. Athletes with above-average muscle mass will have ideal weight numbers that are far below any healthy target for them — use body fat percentage instead. Adults over 65 have lower all-cause mortality at BMI 25–27, not at classical ideal weight; chasing a lower number in that age group is associated with higher fracture and frailty risk, not lower.

For everyone else, the averaged number is a realistic intermediate or final target that has decades of clinical grounding behind it. Weigh it alongside the waist-to-height ratio (a better metabolic health indicator for most adults) and the BMI comparison tool to triangulate a target you can actually hold for a decade.