Calculate your ideal body weight using the Hamwi formula (1964). The oldest major IBW equation, widely used in clinical dietetics with the highest per-inch weight increment.
The Hamwi formula (1964) is the oldest of the four major ideal body weight equations and remains popular in clinical dietetics. Developed by Dr. G.J. Hamwi, it features the steepest per-inch increment (2.7 kg for men, 2.2 kg for women) and the lowest base weight for men (48 kg at 5'0").
This means Hamwi gives the lowest IBW for shorter people and the highest for taller people among the four formulas. For a 6'0" man, Hamwi estimates 80.4 kg vs. Devine's 77.6 kg and Miller's 73.1 kg.
Hamwi is particularly popular among registered dietitians for nutritional assessments and caloric need calculations. Its steep slope makes it especially relevant for very tall individuals. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process.
Hamwi is the go-to formula in clinical dietetics. If your dietitian mentions your "ideal body weight," they may be using Hamwi. For taller individuals, Hamwi gives more generous (higher) targets than other formulas, which may be more realistic for larger frames. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Men: IBW = 48.0 + 2.7 × (height in inches − 60) Women: IBW = 45.5 + 2.2 × (height in inches − 60) Result in kg. Frame adjustments: Small frame: IBW − 10% Large frame: IBW + 10%
Result: IBW: 75.0 kg (165 lbs) | Small frame: 67.5 kg | Large frame: 82.5 kg
Male at 5'10" (70 inches): IBW = 48.0 + 2.7 × (70 − 60) = 48.0 + 27.0 = 75.0 kg (165 lbs). For a small frame (−10%): 67.5 kg. For a large frame (+10%): 82.5 kg. Hamwi gives the highest IBW among the four formulas at this height.
Wrist circumference is the simplest proxy for frame size. Measure at the narrowest point, just distal to the wrist bones (styloid processes). Compare to published tables for your height and sex. The Metropolitan Life Insurance Company introduced frame-size categories in the 1940s, and they remain relevant for individualizing weight references.
Published in 1964, Hamwi preceded Devine (1974) by a decade. It was developed when the Metropolitan Life height-weight tables were the primary reference for "desirable" weight. As medical understanding evolved, newer formulas emerged, but Hamwi persisted because of its practical adoption in dietetic training programs and its built-in frame-size adjustment system.
Registered dietitians adopted Hamwi early because it was published in the American Journal of Clinical Nutrition (1964) and included a frame-size adjustment system. Its steep per-inch increment (2.7 kg for men) better reflects the caloric needs of taller individuals, making it useful for meal planning. Many dietetic textbooks and practice guidelines reference Hamwi specifically.
Hamwi has the steepest slope (most weight added per inch) and lowest male base weight. At 5'0": Hamwi 48 kg (lowest), Devine 50, Robinson 52, Miller 56.2 kg (highest). At 6'0": Hamwi 80.4 kg (highest), Devine 77.6, Robinson 74.8, Miller 73.1 kg (lowest). The formulas essentially cross over between 5'3" and 5'5", with Hamwi going from lowest to highest as height increases.
Body frame size refers to the skeletal structure — primarily bone width and density. People with larger frames naturally weigh more (more bone, more muscle attachment points). The simplest assessment uses wrist circumference relative to height. Elbow breadth is another method used by some clinicians. Frame size adjustments (±10%) help customize IBW to individual body structure.
Like all four IBW formulas, Hamwi is empirically derived rather than based on large randomized outcome studies. Dr. Hamwi developed it from clinical observation and the insurance industry's height-weight tables of the era (Metropolitan Life tables). While it has been used clinically for 60+ years, its accuracy is comparable to — not better than — the other three formulas.
Not necessarily. Being 10–20% above any IBW formula is common and often healthy, especially with regular exercise and good body composition. IBW formulas don't account for muscle mass, athletic build, or individual variation. Health markers (blood pressure, blood sugar, cholesterol, fitness level) are far more important than matching a formula-derived number.
No. Hamwi, like the other IBW formulas, was designed for adults. Children and adolescents are still growing, and their healthy weight is assessed using age- and sex-specific growth charts (BMI-for-age percentiles from the CDC or WHO). Applying adult IBW formulas to children would give inappropriate and potentially harmful reference weights.