Ideal Weight Calculator

How to Calculate Ideal Weight

Ideal weight formulas estimate a target body weight from height alone, using a base weight for a 5-foot-tall person plus a fixed increment for every inch above that. Because each formula was derived from a different reference population and era, they use different coefficients — this calculator runs your height through all four side by side so you can see the resulting range at a glance rather than treating any single formula as the definitive answer.

$$\text{Ideal Weight (kg)} = \text{base weight} + \text{coefficient} \times (\text{height in inches} - 60)$$

Height can be entered as feet and inches or as centimeters, using the Unit System selector above — the calculator converts internally to inches before running all four formulas, so the four results are identical either way.

The Four Formulas and Their Coefficients

Devine (1974) — Men: 50 kg + 2.3 kg per inch over 5 feet. Women: 45.5 kg + 2.3 kg per inch over 5 feet. Originally developed to help estimate drug dosing, not as a body-composition target.

Robinson (1983) — Men: 52 kg + 1.9 kg per inch over 5 feet. Women: 49 kg + 1.7 kg per inch over 5 feet. A revision of the Devine formula using an updated reference dataset.

Miller (1983) — Men: 56.2 kg + 1.41 kg per inch over 5 feet. Women: 53.1 kg + 1.36 kg per inch over 5 feet. Another Devine revision, generally producing the highest estimates of the four.

Hamwi (1964) — Men: 48.0 kg + 2.7 kg per inch over 5 feet. Women: 45.5 kg + 2.2 kg per inch over 5 feet. Originally developed as a quick bedside estimate for clinical nutrition dosing.

Worked Example: A 5'10" (70-Inch) Male

Height over 5 feet is $70 - 60 = 10$ inches. Devine: $50 + 2.3 \times 10 = 73.0$ kg. Robinson: $52 + 1.9 \times 10 = 71.0$ kg. Miller: $56.2 + 1.41 \times 10 = 70.3$ kg. Hamwi: $48.0 + 2.7 \times 10 = 75.0$ kg. Averaging the four gives roughly 72.3 kg — the four estimates span about a 5 kg range around that average, illustrating why comparing them side by side is more informative than trusting any single one.

Why These Formulas Were Never About Body Composition

All four formulas were developed in the mid-20th century, and most — Devine and Hamwi especially — were created specifically to help clinicians estimate appropriate medication dosing by body weight when an actual scale reading wasn't practical or available, not to define a healthy or aesthetic body weight. None of the four accounts for muscle mass, bone density, or body fat distribution, which is why a muscular, athletic person and a sedentary person of the exact same height will get the exact same "ideal weight" number from every one of these formulas, despite having very different actual body compositions.

Common Ideal Weight Calculation Mistakes

Treating any single formula's output as a precise personal target, rather than as one data point among several rough estimates, is the most common misuse of these formulas — they were never validated as body-composition targets and shouldn't be used to set a strict numeric goal. Ignoring frame size and muscle mass when interpreting the result is a related mistake, since none of the four formulas can distinguish a lean, muscular body from a higher-body-fat one at the same height and weight. Comparing this page's result directly against a source using a different formula (or against BMI-based guidance) without recognizing they measure different things can also produce confusing, seemingly contradictory numbers.

Ideal Weight Terms You Should Know

Devine Formula — the original and most widely cited height-based ideal body weight formula, developed in 1974 primarily for drug-dosing calculations.

Reference Population — the group of people a formula's coefficients were originally derived from, which varies by formula and by era.

Frame Size — a person's skeletal build (small, medium, large), which none of these formulas account for despite meaningfully affecting a healthy weight range.

Body Composition — the ratio of fat mass to lean mass in the body, a more direct measure of health-relevant body makeup than weight or height alone (see the Body Composition Calculator).