Ideal Body Weight Calculator

The four formulas explained

All four formulas share the same structure: a base weight at 5 feet, plus a fixed amount per inch above 5 feet. They differ in the base weight and per-inch increment. For heights below 5 feet, no downward adjustment is made — the formula returns the base weight.

Hamwi (1964) — Men: 48 kg + 2.7 kg/inch over 5 ft; Women: 45.5 kg + 2.2 kg/inch over 5 ft. Designed for insulin dosing.

Devine (1974) — Men: 50 kg + 2.3 kg/inch over 5 ft; Women: 45.5 kg + 2.3 kg/inch over 5 ft. Still widely cited in pharmacy.

Robinson (1983) — Men: 52 kg + 1.9 kg/inch; Women: 49 kg + 1.7 kg/inch. Proposed as a refinement.

Miller (1983) — Men: 56.2 kg + 1.41 kg/inch; Women: 53.1 kg + 1.36 kg/inch. A second 1983 update.

Why IBW has limitations

These formulas use only height — they ignore frame size, muscle mass, age, and ethnicity. Two people of the same height can have very different healthy weight ranges. Most current guidelines favour using a BMI range of 18.5–24.9 or a body fat percentage range rather than a single IBW number.