CALCULATOR
Ideal Weight Calculator
Devine, Hamwi and Robinson formulas plus the healthy BMI range for your height, and why they disagree with each other.
These formulas date from clinical dosing work, not body composition. Treat the output as a wide range, not a verdict.
Why ideal weight formulas disagree
The Devine, Hamwi and Robinson formulas were developed for clinical purposes, mostly medication dosing, not for body composition or aesthetics. Each was derived from different data, so they return different answers for the same height, often several kilograms apart.
None of them account for muscle mass, bone density or frame size. A trained lifter can sit well above every figure these formulas produce and be in excellent health, which is the clearest sign that they should be read as a wide reference range rather than a target.
The healthy BMI range shown alongside them is broader and generally more useful, but it shares the same blind spot. If you want a number that reflects your actual composition, measure body fat percentage.
The three formulas
Women: 45.5 kg + 2.3 kg per inch over 5 feet
Women: 45.5 kg + 2.2 kg per inch over 5 feet
Women: 49.0 kg + 1.7 kg per inch over 5 feet
All three were developed for clinical purposes, principally medication dosing, where a standardised reference weight is more useful than an individualised one. None was designed to describe a healthy or desirable weight for an individual, which is the use they now get put to online.
How much they disagree
| Height | Devine (men) | Hamwi (men) | Robinson (men) | Healthy BMI range |
|---|---|---|---|---|
| 165 cm | 61.2 kg | 62.1 kg | 61.4 kg | 50-68 kg |
| 175 cm | 70.3 kg | 72.8 kg | 69.0 kg | 57-76 kg |
| 185 cm | 79.4 kg | 83.4 kg | 76.5 kg | 63-85 kg |
At 185 cm the formulas differ by nearly 7 kg for the same person. That spread is a fair indication of their precision, and the healthy BMI range is wider still because it acknowledges that people of the same height can be healthy at different weights.
What to use instead
- Body fat percentage separates lean mass from fat, which weight alone cannot do.
- Waist circumference tracks the fat distribution most associated with metabolic risk.
- Strength and performance tell you whether the lean mass you carry is functional.
- Trend over time matters more than any single figure: the direction beats the number.
Frequently asked questions
Which ideal weight formula is most accurate?
Should I aim for my ideal body weight?
Why is my ideal weight lower than my current weight?
Do these formulas work for women?
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General information, not medical advice. Consult a qualified professional before changing your diet, especially with a medical condition.