Ideal Weight Calculator
Compare your ideal body weight by the Devine, Robinson, Miller and Hamwi formulas and the healthy BMI range — with an honest note on where these numbers came from.
Ideal Weight Calculator: with the default inputs, devine (1974) is 160.9 lb.
The formula most clinicians and drug-dosing references use.
- Robinson (1983)
- 156.5 lb
- Miller (1983)
- 155 lb
- Hamwi (1964)
- 165.3 lb
- Average of the four
- 159.4 lb
- Healthy BMI range from (BMI 18.5)
- 128.9 lb
- Healthy BMI range to (BMI 24.9)
- 173.5 lb
Assumptions
- Formulas are applied exactly as published, in kilograms per inch over 5 feet, and extrapolated linearly below 5 feet.
- The healthy range uses the WHO adult BMI cut-offs 18.5–24.9; some populations (notably Asian ancestry) use lower cut-offs.
- No adjustment is made for frame size, age or muscle mass.
| Formula | Rule (men) | Result(lb) |
|---|---|---|
| Devine (1974) | 50 kg + 2.3 kg per inch over 5 ft | 160.9 lb |
| Robinson (1983) | 52 kg + 1.9 kg per inch over 5 ft | 156.5 lb |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 155 lb |
| Hamwi (1964) | 48 kg + 2.7 kg per inch over 5 ft | 165.3 lb |
All four are linear in height, which is why they disagree more the further you are from average height.
How this is worked out
The formula
Devine (1974): men 50.0 kg + 2.3 kg/in over 5 ft · women 45.5 kg + 2.3 kg/in Robinson (1983): men 52.0 kg + 1.9 kg/in · women 49.0 kg + 1.7 kg/in Miller (1983): men 56.2 kg + 1.41 kg/in · women 53.1 kg + 1.36 kg/in Hamwi (1964): men 48.0 kg + 2.7 kg/in · women 45.5 kg + 2.2 kg/in Healthy BMI range: 18.5 × height (m)² to 24.9 × height (m)²
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Height
- A number.in ft, in, cm, m · from 3.5 to 8.5 · defaults to 5.8333
- Sex
- Choose one of 2 options.Male · Female
What you get back
- Devine (1974)main answer
- The formula most clinicians and drug-dosing references use.
- Robinson (1983)
- Miller (1983)
- Hamwi (1964)
- Average of the four
- Healthy BMI range from (BMI 18.5)
- Healthy BMI range to (BMI 24.9)
What this assumes
- Formulas are applied exactly as published, in kilograms per inch over 5 feet, and extrapolated linearly below 5 feet.
- The healthy range uses the WHO adult BMI cut-offs 18.5–24.9; some populations (notably Asian ancestry) use lower cut-offs.
- No adjustment is made for frame size, age or muscle mass.
About this calculator
"Ideal body weight" sounds like a health target. It isn't, quite. The four classic formulas here were built to dose drugs and read life-insurance tables, not to tell you what you should weigh — and knowing that is the key to using them sensibly.
Where the formulas come from
- Hamwi (1964) was a rule of thumb from a diabetes handbook: 106 lb for the first 5 ft of a man's height plus 6 lb per inch (100 lb + 5 lb for women).
- Devine (1974) converted Hamwi to kilograms to estimate creatinine clearance for gentamicin dosing. It stuck; today it's the "IBW" behind most clinical drug-dosing calculators and ventilator tidal-volume settings.
- Robinson and Miller (1983) re-fitted the idea to Metropolitan Life insurance tables — the weights at which policyholders lived longest — using a different height–weight slope.
None were validated against health outcomes in the modern sense, and Pai & Paloucek's 2000 review found little evidence behind the original numbers beyond convention.
How to read the result
The Devine value is shown first because it's the one you'll meet in medicine. The average of the four smooths out their different slopes. But the most useful line is the healthy BMI range: everything from BMI 18.5 to 24.9 is associated with similar mortality risk in large cohort studies, and it's a range for a reason. For a 5'10" man that's roughly 129–174 lb — a 45-lb window that easily contains all four "ideal" points.
Limits
- The formulas ignore frame size, muscle mass, age and ethnicity. A lean, muscular person will sit above every formula and be perfectly healthy.
- They're linear in height and were fitted around average heights; at 5'0" or 6'5" they diverge from each other and from the BMI range.
- For anyone under 5 ft they simply weren't defined; the calculator extrapolates and warns.
If you want a personal target, combine the BMI range with waist-to-height ratio (under 0.5) and, if you can measure it, body fat percentage. Those track health far better than a single "ideal" number.
Frequently asked questions
▸Which ideal weight formula is most accurate?
None is 'accurate' in a health sense — they're conventions. Devine is the clinical standard for drug dosing; for a health target, the BMI 18.5–24.9 range plus waist-to-height ratio is better supported.
▸Why do the formulas give different answers?
They use different slopes per inch of height (1.36 to 2.7 kg). Near average height they agree within a few kilograms; for very short or tall people they spread out.
▸Is my ideal weight the same as my goal weight?
Not necessarily. Many people are healthiest somewhat above the formula value, especially if they carry muscle. Use the BMI range as the boundary and body composition to fine-tune.
▸Why is ideal body weight used in medicine?
Many drugs distribute mainly in lean tissue, so dosing on actual weight overdoses heavier patients. IBW (or an adjusted weight between the two) gives a safer estimate of lean mass.
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