What Is Ideal Body Weight?
Ideal Body Weight (IBW) formulas estimate a target weight based on height and sex. They were originally developed for medical use, primarily for calculating medication doses and assessing nutritional needs, not as aesthetic or fitness targets.
Because IBW formulas were designed for medical contexts, they don't account for muscle mass. A muscular person may be well above their calculated IBW while being in excellent health.
The Four Formulas
Each formula was developed at a different time and for different purposes:
| Formula | Year | Notes |
|---|---|---|
| Devine | 1974 | Most widely used in clinical practice. Originally for drug dosing. |
| Robinson | 1983 | Refined Devine to better match population data. |
| Miller | 1983 | Developed alongside Robinson. Tends to give lowest estimate. |
| Hamwi | 1964 | Oldest formula. Rule-of-thumb approach, slightly higher estimates. |
Frame Size Adjustment
Most IBW formulas can be adjusted by -10% for body frame size. People with a larger skeletal frame (broad shoulders, wider bone structure) naturally weigh more at the same height. Large frame: add up to 10%. Small frame: subtract up to 10%.
A rough way to determine frame size: wrap your thumb and middle finger around your wrist. If they overlap = small frame. If they just touch = medium. If there's a gap = large frame.
A Better Approach To Setting Weight Goals
Rather than targeting a specific scale weight, consider setting goals based on a combination of: BMI (18.5-24.9), body fat percentage (6-17% for men, 14-24% for women), and waist circumference (below 94cm for men, 80cm for women per NHS guidelines). These three measures together give a far more complete picture of health than scale weight alone.
