What this tool does
Four adult IBW equations appear side by side, plus their midpoint in kg and lb. They were built for population and pharmacology contexts, not to tell a lifter what they should weigh on meet day. Height comes from the unit toggle.
How it works
Each formula starts from a base weight at 5 feet and adds a sex-specific increment per inch over 5 feet. Below 5 feet the extra-inch term is floored at zero here, which is a limitation — these equations were never great for very short adults.
Formula and methodology
Inches over 5 ft = max(height_in − 60, 0). Men: Hamwi 48 + 2.7×over; Devine 50 + 2.3×over; Robinson 52 + 1.9×over; Miller 56.2 + 1.41×over (kg). Women: Hamwi 45.5 + 2.2×over; Devine 45.5 + 2.3×over; Robinson 49 + 1.7×over; Miller 53.1 + 1.36×over. Midpoint is the mean of the four. Honest limit: not validated as a personal “ideal.”
How to interpret the result
If you already train and sit above the midpoint with a small waist, you do not owe the midpoint a cut. If you sit far above and fitness is sliding, use TDEE tools, not Hamwi as a shame number. BMI and waist still add context these formulas lack.
Example
A 180 cm man is about 10.9 inches over 5 feet. Hamwi 77.3 kg, Devine 75.0 kg, Robinson 72.6 kg, Miller 71.5 kg. Midpoint 74.1 kg — a range, not a verdict. A 90 kg lifter can be leaner than a 74 kg inactive person.
Common mistakes
- Picking the lowest of the four because it looks more disciplined.
- Using IBW as a fight-camp weight without considering muscle.
- Applying these to adolescents.
- Ignoring that short and tall adults were never the design center.
When this estimate may be off
- High muscle mass, pregnancy, or amputations.
- Heights well below 5 feet.
- You need a clinical nutrition IBW adjustment (spinal cord injury, etc.).
- Ethnic-specific healthy-weight guidance from a clinician differs.