Ideal Weight Calculator

Background.

This ideal weight calculator returns four classical estimates of ideal body weight (IBW) — the Devine (1974), Hamwi (1964), Robinson (1983), and Miller (1983) formulas — side by side with the World Health Organization's healthy-BMI range (18.5–24.9 kg/m²) for the same height. We return four numbers rather than one because there is no scientifically agreed single ideal weight for a given height, and any calculator that claims to deliver one is hiding the disagreement under a rounded average. Each of the four formulas was published for a specific clinical purpose, fitted to a particular reference population, and treats the relationship between height and weight slightly differently. The differences are not academic: at 180 cm (5 ft 11 in) the four formulas span roughly 75–82 kg for a man and 67–75 kg for a woman, a 7–8 kg gap that easily covers the difference between a lean athlete and a sedentary office worker of the same height. Putting them next to each other — and next to the WHO healthy-BMI range, which most contemporary public-health bodies now treat as the more defensible reference — lets you see the spread instead of the single point.

The phrase 'ideal weight' carries a lot of historical baggage. The earliest ancestor of every formula on this page is the 1959 Metropolitan Life Insurance height-weight table, which tabulated the weights at which life-insurance policy-holders had the lowest mortality, segmented by sex and 'frame size' (small, medium, large). Those tables were not derived from physiological optima but from actuarial outcomes on a self-selected, mostly white, mostly North American insured population in the middle of the twentieth century. The four formulas below are essentially algebraic compressions of that table. Bruce Hamwi published the earliest in 1964 in a chapter of the American Diabetes Association's Diabetes Mellitus: Diagnosis and Treatment, intending it as a quick mental-math aid for clinicians estimating caloric and insulin needs in newly diagnosed patients. Ben Devine adapted Hamwi's structure in 1974 in Drug Intelligence and Clinical Pharmacy to dose gentamicin and other aminoglycoside antibiotics in obese patients — the drug's distribution volume tracks lean rather than total body mass, and Devine needed a height-only proxy for lean weight. Robinson and colleagues at the University of Calgary, and Miller and colleagues at the University of Mississippi, both published refinements in 1983 in the American Journal of Hospital Pharmacy, attempting to fit Metropolitan Life's medium-frame values more closely than Devine had. None of these authors had body composition, ethnicity diversity, or modern obesity-prevalence data in front of them, and none claimed their formula was a physiological ideal. They were dosing tools and meal-planning shortcuts that escaped clinical pharmacy into the wider culture and were rebranded as 'ideal' weights long after the fact.

The contemporary medical consensus, repeatedly stated by the WHO, the U.S. Centers for Disease Control and Prevention, the National Institutes of Health, and the U.K. National Health Service, is that 'ideal weight' as a single number is not a useful clinical concept for individuals. A range is. The WHO defines the adult healthy-weight band as a body mass index of 18.5–24.9 kg/m² — derived from large-scale epidemiology in which all-cause mortality and the incidence of obesity-related disease (type 2 diabetes, cardiovascular disease, several cancers) are lowest across most ethnic groups. Below 18.5 is classified as underweight, 25.0–29.9 as overweight, and 30 and above as obese, with further subdivisions for severe obesity. This range, applied to your height, is the BMI low/high pair this calculator returns alongside the four classical formulas.

The BMI range is not a perfect tool either — at the individual level it cannot distinguish muscle from fat, it systematically misclassifies muscular athletes and aging adults with sarcopenia, and the optimal cut-offs vary by ancestry. The WHO's 2004 expert consultation acknowledged that South Asian, East Asian, and Southeast Asian populations carry higher cardiometabolic risk at lower BMIs than European populations, and recommended that policymakers in those regions consider lowered thresholds (overweight ≥23.0, obese ≥27.5) for public-health action. Conversely, populations with historically higher lean mass — including some Pacific Islander, Black, and African-descent groups — have lower disease risk at the same BMI than the WHO reference. The U.S. National Institutes of Health and the American Heart Association both recommend that clinicians treat BMI as a starting screening tool to be followed by waist circumference, body-fat percentage, blood pressure, glucose, and lipid measurements before any individual conclusion is drawn. Treat the numbers on this page the same way.

A useful interpretation pattern: if your current weight sits inside the healthy-BMI band and within the spread of the four classical formulas, you have very weak evidence that weight is a health problem and strong evidence that other markers (cardiorespiratory fitness, waist-to-height ratio, lab values) are the right place to look. If your weight sits well above the BMI upper bound and well above all four formulas, the case for a calorie deficit guided by a TDEE and BMR calculation is stronger. If you are an athletic adult whose body composition the calculator clearly mishandles — a powerlifter at 100 kg with 12% body fat will exceed every IBW estimate and every BMI upper bound while being objectively lean — discard the formulas and use a body-fat measurement instead. Below the calculator we walk through the algebra of each formula, the populations they were fit to, the limitations the original authors flagged but the popular literature has dropped, and a worked example for a 175 cm adult.

What is ideal weight calculator?

An ideal weight calculator returns one or more height-based estimates of an adult's 'ideal' or 'reference' body weight, originally developed for clinical drug dosing and diabetes meal-planning rather than as physiological optima. This calculator reports four of the most widely cited classical formulas — Devine (1974), Hamwi (1964), Robinson (1983), and Miller (1983) — together with the World Health Organization healthy-weight range (BMI 18.5–24.9 kg/m²) for the same height. The four formulas share the same structural form (a base weight at 5 ft of height plus a per-inch increment above 5 ft, with separate constants for men and women) and trace back to the 1959 Metropolitan Life Insurance height-weight tables, which were tabulations of the body weights at which life-insurance policy-holders had the lowest observed mortality. Each formula was a clinician's algebraic compression of that table, fit to either the medium-frame midpoint or the lean-mass proxy needed for aminoglycoside antibiotic dosing. None of the authors claimed the result was a physiological ideal, and none of the formulas account for body composition, ethnicity, age, frame size, training status, or any other factor that meaningfully modifies a person's healthy weight at a given height. The WHO healthy-BMI range, returned as a low/high kilogram pair, is derived instead from large-scale epidemiology in which all-cause mortality and the incidence of obesity-related disease are lowest, and is the more defensible reference for individuals — though it too has known limitations for muscular athletes and for several non-European ancestral groups whose cardiometabolic risk thresholds sit at different BMI cut-offs.

How to use this calculator.

1. 01Select your sex. Every classical formula on this calculator uses a different base constant for men and women, reflecting the sex-segmented Metropolitan Life tables they were fitted to in the 1960s and 1970s.
2. 02Enter your standing height in centimetres. The calculator converts internally to inches above 5 ft (152.4 cm), which is the unit the original papers used.
3. 03Read the four classical ideal-weight estimates. Devine is the primary value because it is by far the most cited in clinical practice; Hamwi is the oldest; Robinson and Miller are the 1983 refinements that better track Metropolitan Life medium-frame weights.
4. 04Compare the four numbers to each other. Their spread is the honest answer to 'what should I weigh?' — there is no single ideal, and the gap between the lowest and highest of the four is usually 5–10 kg.
5. 05Compare them to the BMI healthy-weight range (18.5–24.9 kg/m²) returned underneath. If your current weight falls inside both the formula spread and the BMI range, the evidence that weight is a clinical concern is weak.
6. 06If you are a muscular athlete, an older adult with sarcopenia, of South/East Asian or Pacific Islander/Black African ancestry, or otherwise outside the mid-20th-century North American insured population the formulas were fit to, treat the numbers as a starting reference and follow up with a body-fat measurement, a waist-to-height ratio, and your fasting glucose and lipid markers.

The formula.

All four classical formulas share the same shape: base weight at 5 ft of height (60 inches, 152.4 cm) plus a per-inch increment for every inch above 5 ft, with separate base and increment constants for men and women. The calculator converts the height you enter in centimetres into inches above 5 ft using inchesAbove5ft = (heightCm − 152.4) ÷ 2.54, then applies each formula directly. The Devine (1974) formula is 50 kg + 2.3 × inchesAbove5ft for men and 45.5 kg + 2.3 × inchesAbove5ft for women. The Hamwi (1964) formula is 48 kg + 2.7 × inchesAbove5ft for men and 45.5 kg + 2.2 × inchesAbove5ft for women — note the larger per-inch increment for men, which makes Hamwi the most generous formula at tall heights. The Robinson (1983) formula is 52 kg + 1.9 × inchesAbove5ft for men and 49 kg + 1.7 × inchesAbove5ft for women. The Miller (1983) formula is 56.2 kg + 1.41 × inchesAbove5ft for men and 53.1 kg + 1.36 × inchesAbove5ft for women — Miller has the highest 5 ft baseline but the lowest per-inch slope, which makes it the flattest of the four across the adult height range. For heights below 5 ft (152.4 cm) the original papers do not define a behaviour; the calculator extrapolates linearly using the same coefficients, which produces lower numbers than the formulas were validated on and which should be treated as illustrative rather than prescriptive. The WHO healthy-weight range is computed independently from BMI as bmiLowKg = 18.5 × (heightCm ÷ 100)² and bmiHighKg = 24.9 × (heightCm ÷ 100)², which together bound the body mass index range the WHO classifies as healthy for adults. The four classical results and the BMI band are not adjusted for body composition, age, ancestry, frame size, or training status — adjustments any of those factors would normally require are outside the scope of the formulas and should be made qualitatively against the body-fat percentage, waist circumference, and metabolic markers that modern obesity guidelines treat as the more defensible primary references.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Devine BJ — Gentamicin therapy. Drug Intelligence and Clinical Pharmacy 8(11):650–655 (1974). The original publication of the Devine ideal body weight formula, written to dose aminoglycoside antibiotics in obese patients.
2. [2]Hamwi GJ — Therapy: changing dietary concepts. In: Danowski TS, editor. Diabetes Mellitus: Diagnosis and Treatment, Volume 1. American Diabetes Association, New York (1964), pages 73–78. The original publication of the Hamwi rule of thumb for ideal body weight in diabetes meal-planning.
3. [3]Robinson JD, Lupkiewicz SM, Palenik L, Lopez LM, Ariet M — Determination of ideal body weight for drug dosage calculations. American Journal of Hospital Pharmacy 40(6):1016–1019 (1983). The Robinson refinement of Devine fitted more closely to the Metropolitan Life Insurance medium-frame tables.
4. [4]Miller DR, Carlson JD, Loyd BJ, Day BJ — Determining ideal body weight (and mass). American Journal of Hospital Pharmacy 40(10):1622–1625 (1983). The Miller refinement of Devine, published in the same year and journal as Robinson and intended as a flatter alternative across the adult height range.
5. [5]Metropolitan Life Insurance Company — New weight standards for men and women. Statistical Bulletin of the Metropolitan Life Insurance Company 40:1–4 (1959). The actuarial height-weight tables that all four classical ideal-weight formulas were fitted to.
6. [6]World Health Organization — Obesity and overweight fact sheet. WHO, Geneva, updated regularly. Defines the adult healthy-weight BMI band of 18.5–24.9 kg/m² and the overweight/obesity thresholds at 25 and 30 used in this calculator's BMI range output.
7. [7]WHO Expert Consultation — Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. The Lancet 363(9403):157–163 (2004). Establishes the lowered BMI public-health action points (overweight ≥23.0, obese ≥27.5) for South Asian and East Asian populations and is the basis for the ancestry caveat in this calculator's content.
8. [8]Pai MP, Paloucek FP — The origin of the 'ideal' body weight equations. Annals of Pharmacotherapy 34(9):1066–1069 (2000). Historical review tracing all four classical IBW formulas back to the 1959 Metropolitan Life Insurance tables and documenting that none was derived from a physiological optimum.