How this calculator works
Ideal body weight (IBW) formulas were originally developed to estimate a reference weight for drug dosing, not to define a personal health target. This calculator runs your height through the four formulas most often cited alongside each other — Devine, Robinson, Miller and Hamwi — and shows their average next to the BMI-based healthy weight range for your height.
The four formulas were all derived from older height-weight tables and agree with each other closely for average heights, but they diverge more at very short or very tall statures. None of them account for muscle mass, frame size, sex-specific fat distribution, or age, so treat the output as a rough anchor rather than a personal prescription. These results are estimates, not medical advice.
The four formulas
Devine (1974), men: 50 kg + 2.3 kg × (height in inches − 60)Devine (1974), women: 45.5 kg + 2.3 kg × (height in inches − 60)Hamwi (1964), men: [106 lb + 6 lb × (height in inches − 60)] × 0.45359237 kg/lbHamwi (1964), women: [100 lb + 5 lb × (height in inches − 60)] × 0.45359237 kg/lbRobinson (1983), men: 52 kg + 1.9 kg × (height in inches − 60)Robinson (1983), women: 49 kg + 1.7 kg × (height in inches − 60)Miller (1983), men: 56.2 kg + 1.41 kg × (height in inches − 60)Miller (1983), women: 53.1 kg + 1.36 kg × (height in inches − 60)60 inches (5 feet) is the reference height each formula was built around. Devine and Robinson/Miller were published directly in kilograms per inch; Hamwi was published in pounds per inch and is converted here with the exact 0.45359237 kg/lb factor. Devine is the most widely used in clinical dosing; Robinson and Miller are later refinements against updated height-weight data; Hamwi is an older nursing/dietetics rule of thumb.
Worked example: man, 5'10" (177.8 cm)
- Height over the 5-foot reference: 177.8 cm = 70 inches exactly, so 70 − 60 = 10 inches.
- Devine = 50 + 2.3 × 10 = 73.0 kg. Hamwi = (106 + 6 × 10) lb = 166 lb × 0.45359237 ≈ 75.3 kg.
- Robinson = 52 + 1.9 × 10 = 71.0 kg. Miller = 56.2 + 1.41 × 10 = 70.3 kg.
- Average of the four: (73.0 + 75.3 + 71.0 + 70.3) ÷ 4 ≈ 72.4 kg (about 160 lb).
Frequently asked questions
Is one ideal-weight formula more trustworthy than the others?
None is more 'correct' than the others — they are competing estimates fit to different historical height-weight tables. Devine is the most widely used today because it underlies common drug-dosing calculations, but all four are equally rough for general weight guidance.
Why do the formulas disagree with the BMI-based range?
IBW formulas assume a single target weight per height. The BMI-based range (18.5-24.9) instead spans a whole band of weights considered normal, which is why it's usually wider than any single IBW formula's number.
Do these formulas account for muscle mass?
No. A muscular, athletic person can weigh well above their IBW formula result while carrying very little body fat. For a fitness-focused estimate, body fat percentage is more informative than any height-only formula.
Should I try to hit the exact average weight shown?
Not necessarily. These are population-derived estimates and not medical advice. Talk to a doctor or registered dietitian before setting a specific weight goal, especially if you have a medical condition.
Does this calculator work if I enter my height in centimeters instead of inches?
Yes. Although all four original formulas (Devine, Robinson, Miller and Hamwi) were published using height in inches, this calculator accepts metric height and converts it before applying the same formulas, then displays the result in kilograms or pounds as selected. The underlying math and the four results are identical either way — only the units you see change.