Ideal Weight Calculator
Four standard formulas (Devine, Robinson, Miller, Hamwi) plus BMI healthy range. Population-level estimates — individual targets vary.
Ideal weight estimates
What "ideal weight" actually means
“Ideal body weight” (IBW) formulas were developed primarily for clinical purposes — calculating drug doses, ventilator tidal volumes, and other medical decisions where a standardized weight is useful. They're population-level approximations, not individual goals. Aiming to hit your IBW exactly isn't a meaningful health target.
A more useful concept for individuals: the BMI healthy range (18.5–24.9), which corresponds to the band of weight associated with the lowest all-cause mortality in epidemiological studies. The calculator shows this range alongside the formula results.
The four formulas
Devine (1974)
Developed by Dr. Ben Devine for calculating drug doses based on lean body mass. Most cited in clinical literature. Men: 50 kg + 2.3 kg per inch over 5 ft. Women: 45.5 kg + 2.3 kg per inch over 5 ft. The original use was practical (drug dosing for hospitalized patients), not as a general health target.
Robinson (1983)
Slight modification to Devine's formula. Men: 52 kg + 1.9 kg per inch over 5 ft. Women: 49 kg + 1.7 kg per inch over 5 ft. Tends to give slightly different (often slightly higher) results than Devine for taller individuals.
Miller (1983)
Another 1983 update. Men: 56.2 kg + 1.41 kg per inch over 5 ft. Women: 53.1 kg + 1.36 kg per inch over 5 ft. Generally gives the lowest results among the four formulas at average heights.
Hamwi (1964)
The oldest and simplest. Men: 48 kg + 2.7 kg per inch over 5 ft. Women: 45.5 kg + 2.2 kg per inch over 5 ft. Easy mental math — the additions per inch are larger than Devine's, giving higher results at greater heights.
Why all four?
All four were developed for similar purposes (clinical drug dosing) but use slightly different population data and calibrations. None has clearly “won” — different clinicians use different formulas based on local convention or specific drug-dosing protocols. Showing all four gives you a sense of the natural variation. The average is often a reasonable middle estimate.
Limitations these formulas all share
- No body composition awareness — a 6' bodybuilder and a 6' sedentary person get the same “ideal weight,” even though their actual healthy weights are very different.
- Linear in height — real weight scales as roughly height² (BMI), not height¹. Tall people are slightly underestimated by linear formulas.
- Binary sex — formulas use male/female with no nuance for hormone treatments, intersex variation, or transgender individuals.
- Population-specific — most based on US/European population data from the mid-20th century. Less accurate for other ancestries.
- No age adjustment — older adults often have lower bone density and less muscle, making formula targets unrealistic.
Better alternatives for individual targets
- BMI healthy range: 18.5–24.9. Range, not a single number. See our BMI Calculator.
- Body fat percentage: 6–24% men, 14–31% women (varies by age and athletic level). See our Body Fat Calculator.
- Waist-to-height ratio: keep waist under half your height. Better at predicting cardiovascular risk than weight alone.
- Waist circumference (alone): under 40 in (men) or 35 in (women) is associated with lower metabolic risk.
- Fitness markers: VO2max, resting heart rate, blood pressure, lipid panel, fasting glucose. These describe metabolic health directly.
When ideal weight formulas matter
Where these formulas are useful: clinical contexts where a standardized estimated weight is needed — drug dosing for hospitalized patients (especially when scale weight isn't available or accurate), ventilator settings (tidal volume), surgical planning, and burn-care calculations. For everyday personal use, BMI range and body composition are more meaningful.
Pair this with our BMI Calculator for the more individual-relevant healthy weight range, Body Fat Calculator for composition, and TDEE Calculator for daily calorie targets.