Ideal weight calculator
Ideal weight is a calculated reference point rather than a target: the Devine formula gives one number from height and sex, while body mass index gives a whole range within which a healthy weight can sit anywhere.
- Healthy range (BMI 18.5–24.9)
- 56.7–76.3 kg
Rates and thresholds
- Devine, men
- 50 kg + 2.3 kg per inch over 152.4 cm
- Devine, women
- 45.5 kg + 2.3 kg per inch over 152.4 cm
- Healthy range
- 18.5 × height² to 24.9 × height² (height in metres)
- Example: 180 cm, man
- 75.0 kg (Devine), 59.9–80.7 kg (BMI)
- Example: 165 cm, woman
- 56.9 kg (Devine), 50.4–67.8 kg (BMI)
How is ideal weight calculated?
The Devine formula starts from a base weight — 50 kg for men, 45.5 kg for women at five feet, or 152.4 cm — and adds 2.3 kg for every further inch. For a man of 180 cm the excess over 152.4 cm is 27.6 cm, or 10.87 inches, giving 50 + 25.0 = 75.0 kg.
Why do calculators disagree about ideal weight?
Several formulas are in use — Devine, Robinson, Miller, Hamwi, Broca — and each was built for its own purpose, often drug dosing rather than health advice. At the same height they differ by several kilograms, so a single number is no more precise than the range it falls inside.
Does ideal weight apply to everyone?
No. The formula sees only height and sex — not muscle mass, frame width, age or health. An athlete lands below their real weight, and in older age a little extra can be protective. Pregnancy, growth and illness call for a doctor's assessment rather than a calculator.
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