A walkthrough, end to end.
- 1
Enter your height and sex. The four formulas all add a fixed weight per inch above 5'0", with sex-specific base values reflecting average body composition differences.
- 2
Read the ‘average’ result at the top — that's the mean of the four formulas. Below it you'll see each formula's individual answer.
- 3
Pick the formula that matches whatever source you're comparing against. Drug-dosing research uses Devine; updated guidelines often use Robinson; dietetics traditionally uses Hamwi.
- 4
Treat any of these as a reference, not a target. None account for body composition — a muscular athlete can be well above ‘ideal’ weight and still healthy.
The four classic formulas
All four formulas use the same shape — a base weight plus a fixed amount per inch above 5'0". Each was validated on different populations decades apart, which is why their numbers diverge slightly. Devine (1974) is the most cited clinically because most drug-dosing studies use it as the reference body weight.
What you can do with this.
Ideal weight for men
All four formulas use a higher base for men (50–56.2 kg) than for women (45.5–53.1 kg) at the same height. The differences reflect average lean-mass differences. Men's ‘ideal’ values are typically 4–6 kg above women's at the same height.
Ideal weight for women
Women's ideal weight formulas account for typical higher essential body fat. The Robinson and Miller formulas tend to land slightly higher than Devine for women, partly because they're more recent and updated for modern populations.
Devine formula — drug dosing reference
Most published drug-dosing protocols use the Devine formula (1974) as the reference for ‘ideal body weight.’ Aminoglycosides, anesthetics, and many other drugs are dosed by IBW or an adjusted IBW for obese patients.
Robinson vs Devine — what's the difference?
Robinson (1983) is essentially an updated Devine — same shape, slightly different constants. Devine uses 50 kg base for men with 2.3 kg per inch; Robinson uses 52 kg with 1.9 kg per inch. The two diverge most at extreme heights.
Hamwi formula — quick rule of thumb
Hamwi (1964) is the formula dietitians use for fast bedside estimates. Men: 106 lb at 5'0" + 6 lb per inch. Women: 100 lb at 5'0" + 5 lb per inch. Easy to remember; still lands within ~2 kg of the more modern formulas.
Why your ideal weight isn't a target
These formulas predate modern body-composition science. They're still useful for drug dosing and rough comparisons but they don't know if you're a marathon runner, a bodybuilder, or an office worker. For real targets, work with body fat percentage and overall fitness markers.
Ideal weight calculator 2026 — what's current
The four classic formulas (Devine, Robinson, Miller, Hamwi) are still the standard 2026 references for ideal body weight in clinical contexts — drug dosing protocols continue to cite Devine specifically. Modern weight-target conversations have largely moved to BMI ranges or body fat percentage targets, but IBW remains useful for medication calculations and cross-source comparisons.
Frequently asked.
It depends on context. For drug dosing, Devine is standard. For dietetics, Hamwi is the bedside default. For modern research, Robinson updates Devine. The four formulas usually agree within 5–6 kg at typical adult heights.
BMI gives you a range (the healthy range at your height). Ideal weight gives you a single number that came from older research. Both are population averages — neither accounts for muscle vs fat. BMI is more commonly cited today; ideal weight persists for clinical reasons.
Probably not — none of these formulas account for body composition. A heavily-muscled athlete can be well above 'ideal weight' and still very healthy. For muscular people, body fat percentage is a better metric than scale weight.
On average, men have more lean mass per kg of body weight, so the same height carries more 'ideal' weight. The constants differ by 4–6 kg at typical adult heights.
These formulas don't include age. Some research suggests slightly higher ideal weights for adults 65+ may be protective, but none of the four classic formulas adjust for that. WHO and other modern guidance mostly uses BMI bands instead.
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