Ideal Weight Calculator
Ideal body weight from height and sex using Devine, Robinson, Miller, and Hamwi formulas
Last updated:
What this calculator computes
The ideal-weight calculator estimates a target body weight from height and sex using four classical clinical formulas — Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). All four were originally developed for clinical drug-dosing calculations rather than aesthetic or fitness targets, and all produce similar but not identical figures: the Devine formula is the most commonly cited in clinical practice, Robinson is the most contemporary, Hamwi is the simplest to compute by hand, and Miller is the most generous (returning the highest "ideal" weight of the four). For a 178 cm tall male the formulas return Devine 75.7 kg, Robinson 75.2 kg, Miller 75.4 kg, and Hamwi 79.7 kg — a spread of about 5 kg across the methods, which reflects the inherent ambiguity in defining a single "ideal" body weight from height alone. The calculator returns all four for transparency. Modern clinical and fitness practice has largely moved away from formula-based ideal-weight targets toward body-composition measurement (body-fat percentage, lean body mass, waist-to-height ratio) because formula-based targets ignore frame size and muscle mass; a 178 cm bodybuilder at 90 kg is healthier than a sedentary individual at the formula-derived 75 kg. **The calculator's output is a population-average reference figure, not an individual prescription. For weight-loss or weight-gain plans, consult a registered dietitian or physician who can account for body composition, frame size, age, and individual health context.**
Calculator
The formula
Formula
Devine M: 50 + 2.3·(in over 60) Devine F: 45.5 + 2.3·(in over 60)
Worked example
When to use this calculator
Use this calculator when you want a population-average reference weight as one input into a weight-loss or weight-gain decision, knowing that body-composition measurements (body-fat percentage, waist-to-height ratio) are more meaningful than any height-only formula. The most common scenarios are casual fitness goal-setting (where the calculator's range provides a sanity-check against unrealistic targets), clinical drug-dosing (where the Devine formula is widely used to compute the dose for medications that scale with lean body mass rather than total body weight, particularly for obese patients where total body weight overdoses fat-soluble drugs), and historical-context understanding (where pre-DEXA-era ideal-weight tables still appear in clinical-pharmacology references and life-insurance underwriting). The calculator does not replace measurement-based assessment of body composition or health; for individual weight goals, work with a dietitian who can incorporate frame size, muscle mass, age, ethnicity, and clinical history that the four formulas all ignore.
Common input mistakes
- Treating the formula-derived ideal weight as a goal weight. The Devine, Robinson, Miller, and Hamwi formulas were developed in the 1960s–80s for clinical drug-dosing calculations and reflect population averages of that era, not optimal individual weights. A muscular 178 cm individual at 85 kg may be healthier than the formula-derived 73 kg target; a sedentary 178 cm individual at 73 kg may be unhealthier than a fit 80 kg counterpart. Use body-fat percentage and waist-to-height ratio for individual assessment.
- Selecting the most flattering formula and using it as the goal. The four formulas span about 5 kg for a typical adult; cherry-picking the most generous (Miller or Hamwi) when overweight or the most demanding (Robinson) when underweight defeats the purpose of consulting them at all. Either present all four (as this calculator does), use the median, or move to a body-composition-based target instead.
Frequently asked questions
What is "ideal body weight"?
Ideal body weight (IBW) is a population-average reference weight derived from height (and sometimes sex) using one of several classical formulas. It was originally defined in the 1960s for life-insurance underwriting and clinical drug-dosing, where a single weight target was needed for protocol-driven calculations. Modern clinical practice increasingly uses body-composition measures (body-fat percentage, waist-to-height ratio, lean body mass) instead, because individual variation in frame size and muscle mass makes any height-only target imprecise.
Why are there four different formulas?
The Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964) formulas were developed independently in different clinical contexts and yield slightly different results for the same height. Devine is the most widely-used in clinical practice; Robinson is the most contemporary; Hamwi is the simplest and most generous; Miller is the most generous of the recent formulas. The spread between them (~5 kg for a typical adult) reflects the inherent ambiguity in defining a single ideal weight from height alone.
How does ideal weight differ from BMI?
BMI is a ratio (weight / height²) that classifies a given weight as underweight, normal, overweight, or obese; it accommodates a range of acceptable weights for a given height. Ideal-weight formulas return a single point value as the population reference. BMI for a 178 cm individual ranges from 58–79 kg in the "normal" category (BMI 18.5–24.9), encompassing all four ideal-weight formula outputs. BMI is more flexible and is preferred over IBW for general health screening.
Should I aim for the calculator's ideal weight?
Treat the four-formula range as one reference among many. For sedentary individuals seeking weight loss, the calculator's range is a reasonable starting target. For muscular individuals, athletes, and those with non-average frame sizes, the formulas systematically under-predict the healthy weight by failing to account for lean mass. Body-composition assessment (body-fat percentage, waist-to-height ratio under 0.5) is a better individual target than any height-only ideal-weight formula.
How is ideal weight used in medicine?
Clinical pharmacology uses ideal weight (commonly via the Devine formula) to compute drug doses for medications whose distribution depends on lean body mass rather than total body weight. Examples include aminoglycoside antibiotics, vasoactive drugs, and some sedatives where dosing on total body weight in obese patients would overdose dangerously. Ideal weight also appears in mechanical-ventilation tidal-volume settings (6–8 mL per kg of ideal weight) where lung capacity scales with height rather than total weight. These clinical uses are why the formulas survive despite their imprecision for individual weight goals.