Ideal Weight Calculator
See your estimated ideal body weight across four classic formulas, plus the healthy weight range your height supports by BMI.
The classic formulas
Each estimates a reference weight from a base plus an increment per inch over 5 feet:
Robinson (men): 52 kg + 1.9 kg × (inches over 60)
Women use lower base weights; a healthy BMI range gives a band instead of a point.
A man at 5'9" (175 cm): the four formulas land around 150–170 lb, and the healthy BMI range is roughly 128–169 lb.
A woman at 5'4" (162.6 cm) — 4 inches over the 5-foot baseline used by each formula:
Devine: 45.5 + 2.3 × 4 = 54.7 kg (≈121 lb). Robinson: 49 + 1.7 × 4 = 55.8 kg (≈123 lb). Miller: 53.1 + 1.36 × 4 = 58.5 kg (≈129 lb). Hamwi: 45.5 + 2.2 × 4 = 54.3 kg (≈120 lb).
The four formulas cluster around 120–129 lb, versus roughly 150–170 lb for the taller male example above — while her healthy BMI range spans a much wider 108–145 lb. The formula cluster sits well inside the BMI band's lower half in both examples, which is typical: these older formulas tend to track closer to the lean end of the modern healthy BMI range.
Take these as reference points, not targets
These formulas were built decades ago for medication dosing, not as health goals — so treat the spread of numbers as a ballpark, not a verdict. A healthy BMI range or, better, a healthy body fat percentage is more meaningful, especially for muscular builds that will read "over" on every height-only formula. If you're aiming to change weight, set a calorie plan with the calorie calculator.
Where each formula came from
| Formula | Introduced | Original purpose |
|---|---|---|
| Hamwi | 1964 | Quick clinical estimate for dietary planning |
| Devine | 1974 | Dosing certain antibiotics by body weight |
| Robinson | 1983 | Refinement of Devine using updated population data |
| Miller | 1983 | Alternative refinement with a smaller per-inch increment |
None of these were designed to define a healthy weight for the general population — they're clinical shorthand tools repurposed for a question they weren't built to answer, which is exactly why they should be read as a rough cluster rather than a precise target.
Common ideal-weight mistakes
- Treating one formula's output as a weight to hit exactly. As both worked examples show, the four formulas already disagree with each other by several pounds — none is more "correct" than the others.
- Ignoring muscle mass and frame size. These formulas use only height and sex, so a lean, muscular build and a higher-body-fat build at the same height get the identical number.
- Anchoring to 40-to-60-year-old clinical formulas instead of a modern BMI range or body fat percentage. The table above shows how old these formulas actually are relative to current health guidance.
Frequently asked questions
What is my ideal body weight?
No single number — formulas cluster around a range (150–170 lb for a 5'9" man). A healthy BMI band is more useful.
Which formula is best?
None is authoritative; they were built for drug dosing. Use a BMI range or body fat instead.
Does ideal weight account for muscle?
No — height and sex only, so athletes read high. Body fat % is better for them.
Where do these formulas come from?
Clinical origins — Devine (1974) was built for antibiotic dosing, not for defining a healthy weight target for the general public.
Should I adjust for frame size?
None of the four formulas here do. A healthy BMI range or body fat percentage is a better modern substitute for an old frame-size adjustment.
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Medical disclaimer: Ideal-weight formulas are rough reference estimates, not health targets or medical advice. Your healthy weight depends on body composition and overall health — consult a healthcare provider. Last reviewed: September 2026.