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Ideal Weight Calculator - 4 Medical Formulas + Healthy BMI Range

Ideal Weight Calculator - 4 Medical Formulas + Healthy BMI Range

Calculate your ideal body weight using the Devine, Robinson, Miller, and Hamwi formulas. Cross-checked against the healthy BMI range (18.5 to 24.9). Free, no signup.

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Formula

Devine=50(M) or 45.5(F)+2.3⋅(hin−60)Robinson=52(M)/49(F)+1.9(M)/1.7(F)⋅(hin−60)Miller=56.2(M)/53.1(F)+1.41(M)/1.36(F)⋅(hin−60)Hamwi=48(M)/45.5(F)+2.7(M)/2.2(F)⋅(hin−60)\begin{aligned} \text{Devine} &= 50_{\text{(M)}}\,\text{or}\,45.5_{\text{(F)}} + 2.3 \cdot (h_{\text{in}} - 60) \\ \text{Robinson} &= 52_{(M)} / 49_{(F)} + 1.9_{(M)} / 1.7_{(F)} \cdot (h_{\text{in}} - 60) \\ \text{Miller} &= 56.2_{(M)} / 53.1_{(F)} + 1.41_{(M)} / 1.36_{(F)} \cdot (h_{\text{in}} - 60) \\ \text{Hamwi} &= 48_{(M)} / 45.5_{(F)} + 2.7_{(M)} / 2.2_{(F)} \cdot (h_{\text{in}} - 60) \end{aligned}

What this ideal weight calculator does

Calculates a 'reference' ideal body weight using four clinically-recognized formulas (Devine, Robinson, Miller, Hamwi) and cross-checks against the healthy BMI range. The four formulas were originally developed for medical purposes - calculating drug dosages and parenteral nutrition requirements - not for personal weight management. They give similar answers for average heights but diverge noticeably for very tall or very short people.

The four formulas in detail

Devine (1974): the most-cited formula, used by hospitals worldwide for dose calculations. Male = 50 kg + 2.3 kg per inch over 5 feet; Female = 45.5 kg + 2.3 kg per inch over 5 feet. Robinson (1983): male = 52 + 1.9 per inch, female = 49 + 1.7 per inch - corrected for what Devine over-estimated in some heights. Miller (1983): male = 56.2 + 1.41 per inch, female = 53.1 + 1.36 per inch - even gentler slope, gives lower numbers for tall people. Hamwi (1964): male = 48 + 2.7 per inch, female = 45.5 + 2.2 per inch - oldest, still used in renal dialysis and some Saudi/Gulf clinical settings.

Known limitations

(1) Height-only - ignores frame size, muscle mass, body fat percentage. A 180 cm bodybuilder and a 180 cm office worker get the same number. (2) Formulas were derived from Western populations in the 1960s to 1980s. Application to Gulf, Asian, or African populations is approximate. (3) Sex is binary in the formulas; no formula for non-binary or pediatric users (different curves apply for children). (4) Below 5 feet (152 cm), the formulas extrapolate downward and become unreliable - use age-appropriate pediatric growth charts instead. (5) Above 200 cm, the linear extrapolation diverges from observed healthy weights for tall athletes.

Ideal weight vs BMI - how they differ

BMI (Body Mass Index) checks whether your CURRENT weight is healthy for your height (BMI = kg / m^2; healthy = 18.5 to 24.9). Ideal weight formulas compute a TARGET number given only your height. The two answers usually overlap but not always: BMI gives a 25-kg-wide range for someone 170 cm tall (53.5 to 72 kg); the formulas give a single number around 65 kg. For most people, the BMI range is more useful because it acknowledges that healthy weight is a range, not a point. Use this calculator's BMI range output as your primary target, and the per-formula breakdown as context.

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Ideal Weight Calculator - 4 Medical Formulas + Healthy BMI Range | HisabWeb