The four classic ideal-weight formulas
Ideal body weight (IBW) formulas were never designed to dictate a single "perfect" number. Most were built for narrow clinical purposes, such as estimating metabolic needs or sizing drug doses. This tool reports four legacy formulas side by side so you can see the range they produce and compare it against the modern BMI reference. Hamwi (1964) grew out of pharmaceutical references. Devine (1974) became the dominant formula for medication dosing. Robinson and Miller (both 1983) attempted to correct earlier formula biases in taller and shorter adults. All four use only height and sex, which is why they disagree substantially with each other and with real-world body composition.
Hamwi (1964) – the pharmacy reference
Hamwi starts with a 5-foot (152.4 cm) baseline of 106 lb (48.1 kg) for men and 100 lb (45.4 kg) for women, then adds 6 lb (2.7 kg) per inch for men and 5 lb (2.3 kg) per inch for women. It is simple and still cited in some pharmacy textbooks, but NIH reviews note it overestimates IBW for shorter frames and underestimates for very tall adults.
Why the healthy BMI range (18.5–24.9) is the gold standard
The CDC and WHO anchor adult weight guidance to the BMI 18.5–24.9 range because it correlates consistently with the lowest all-cause mortality across diverse populations. Unlike the four single-point formulas, the healthy BMI band accounts for the wide spectrum of healthy body builds. A BMI of 22 sits near the middle of the range; the Veloxcalc ideal-weight tool reports this BMI midpoint alongside the four formula outputs. Framing guidance as a range — not a target weight — aligns with modern clinical practice and reduces fixation on an arbitrary single number.
Devine (1974) – the drug-dosing standard
Devine uses 50 kg for men and 45.5 kg for women at 5 feet, plus 2.3 kg per inch for both sexes. It became entrenched because it was adopted into drug-dosing guidelines early, even though its original authors warned it was never validated as a health-weight target. A 2016 Pubmed review on IBW limitations flagged Devine as frequently inconsistent with body composition in modern patient samples.
Using this tool as a range, not a single number
When four respected formulas disagree by 10 kg or more for the same height, the takeaway is not that one formula is "right" — it is that healthy weight occupies a band. Any weight that lands inside the CDC healthy BMI range, is sustainable through consistent nutrition and activity, and is associated with favorable blood markers (blood pressure, lipids, glucose) is a healthy weight for you. Use the outputs to set a realistic starting window and then let how you feel, how you perform, and routine labs guide where within that band you land long-term.
Robinson vs. Miller (both 1983)
Robinson and Miller were published the same year with similar intent: to update Hamwi and Devine for better fit across heights. Robinson uses slightly lower base weights and a gentler per-inch increment, producing the lowest IBW of the four formulas in many heights. Miller is closer to Devine for average stature but diverges at the extremes. Comparing the two side by side illustrates how arbitrary coefficient choices shift the "ideal" by several pounds, reinforcing why the BMI range is the more reliable reference.
Example: Male, 180 cm (≈5'11"). Hamwi = 80.1 kg (176.6 lb), Devine = 75.7 kg (166.9 lb), Robinson = 69.5 kg (153.2 lb), Miller = 75.1 kg (165.6 lb), BMI Midpoint = 71.3 kg (157.2 lb). Healthy BMI range: 59.9–80.7 kg (132.1–177.9 lb). Point: any number inside the BMI range is healthy; don't fixate on one formula's output.