Ideal Weight Calculator
Estimate your ideal body weight with the Robinson, Miller, Devine, Hamwi, Peterson and Lorentz formulas, see the healthy BMI weight range for your height, adjust for body frame size and compare with your current weight.
How it works
Each classic formula = base weight at 5 ft (152.4 cm) + a fixed amount per inch above it · Robinson: 52 kg + 1.9 kg (men), 49 kg + 1.7 kg (women) · Miller: 56.2 + 1.41 (men), 53.1 + 1.36 (women) · Devine: 50 + 2.3 (men), 45.5 + 2.3 (women) · Hamwi: 48 + 2.7 (men), 45.5 + 2.2 (women) · Peterson: 2.2 × BMI + 3.5 × BMI × (height in m − 1.5) · Lorentz: cm − 100 − (cm − 150) ÷ 4 (men) or ÷ 2 (women) · healthy range = 18.5 to 24.9 × height (m)²
Hamwi (1964) and Devine (1974) are the classic clinical formulas; Robinson and Miller (both 1983) refitted them to newer data. All four start from a base weight at five feet and add a fixed amount for each inch above it, so they grow in a straight line with height. Peterson (2016) works backwards from a target BMI (22 by default, adjustable under More options) and Lorentz is a centimeter-based European formula. The healthy BMI range (18.5–24.9) is the population-health band from the WHO and CDC and is usually the most useful single answer. Frame size moves the result: a common clinical rule takes 10% off for a small frame and adds 10% for a large one, and the calculator can judge your frame from wrist circumference using the NIH MedlinePlus table. Enter your current weight to see your BMI and how far you are from the healthy range.
Worked example
A 5′10″ man (177.8 cm, 10 inches above five feet): Robinson = 52 + 1.9 × 10 = 71 kg (156.5 lb), Miller = 56.2 + 1.41 × 10 = 70.3 kg (155.0 lb), Devine = 50 + 2.3 × 10 = 73 kg (160.9 lb) and Hamwi = 48 + 2.7 × 10 = 75 kg (165.3 lb). Peterson at BMI 22 gives 69.8 kg (153.9 lb). The four classic formulas average 159.4 lb, and the healthy BMI range for his height is 129–174 lb. With a large frame, Hamwi rises 10% to 181.9 lb.
Sources: Pai MP, Paloucek FP (2000) — The origin of the "ideal" body weight equations · Peterson CM et al. (2016) — Universal equation for estimating ideal body weight and body weight at any BMI · MedlinePlus (NIH) — Body frame size · CDC — About adult BMI
Frequently asked questions
Why do the formulas disagree?
Each was fitted to different clinical data decades apart. The spread between them is a reminder that "ideal" is a range, not a single number.
How do I find my frame size?
Wrap a tape around your wrist just below the wrist bone and choose "Work it out from my wrist". For men over 5′5″, a wrist of 6.5–7.5 in (16.5–19 cm) is a medium frame; for women the cut-offs depend on height, for example 6–6.25 in (15.2–15.9 cm) is medium for women 5′2″–5′5″. The calculator then takes 10% off the Hamwi weight for a small frame or adds 10% for a large one.
Which formula should I use?
For everyday goals, the healthy BMI range is the most useful, with the formula results as reference points inside it. Doctors and pharmacists often use Devine for drug dosing, and Robinson and Miller tend to sit a little lower for tall people.
Are these valid for very tall or short people?
They extrapolate poorly outside common height ranges, and none apply to children. Below five feet the classic formulas are only extrapolated, so the BMI range is the better guide.
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This is a general educational estimate, not medical advice. Bodies differ — for decisions about diet, training, medication or health conditions, talk to a doctor or registered dietitian.