What is ideal body weight?
Ideal body weight (IBW) is a clinical estimate of the weight at which a person of a given height is likely to have optimal health outcomes. It was originally developed in medical settings to calculate drug dosages and assess nutritional status — not as a personal fitness target.
IBW formulas produce a single number, but your ideal weight is better understood as a range — both because multiple formulas give slightly different results, and because healthy weight varies based on frame size, muscle mass, and individual physiology.
The four formulas
Robinson (1983): Men: 52 + 1.9 × (inches above 60) · Women: 49 + 1.7 × (inches above 60)
Miller (1983): Men: 56.2 + 1.41 × (inches above 60) · Women: 53.1 + 1.36 × (inches above 60)
Hamwi (1964): Men: 48 + 2.7 × (inches above 60) · Women: 45.4 + 2.27 × (inches above 60)
The Devine formula is the most widely used in clinical settings and forms the basis of many drug dosing calculations. The range across all four is more useful than any single figure — treat it as your target zone.
IBW reference by height
| Height | Men | Women |
|---|---|---|
| 155 cm (5'1") | 56.4 kg | 51.9 kg |
| 160 cm (5'3") | 61.4 kg | 56.9 kg |
| 165 cm (5'5") | 66.4 kg | 61.9 kg |
| 170 cm (5'7") | 71.4 kg | 66.9 kg |
| 175 cm (5'9") | 76.4 kg | 71.9 kg |
| 180 cm (5'11") | 81.4 kg | 76.9 kg |
| 185 cm (6'1") | 86.4 kg | 81.9 kg |
Limitations of IBW formulas
IBW formulas were developed on average-framed adults and have three well-documented limitations. Muscle mass is not accounted for — a muscular athlete may weigh 10–15kg above their IBW while carrying very little fat. Frame size is ignored — a large-framed person naturally weighs more than a small-framed person of the same height. Age is not considered — healthy weight tends to shift slightly with age.
Use IBW as a directional reference. Body fat percentage is a more meaningful measure of actual body composition.