What this calculates
Enter your height and sex, in centimetres or feet and inches, and this gives your ideal body weight by four well-known medical formulas — Devine, Robinson, Miller and Hamwi — with their average, and the weight range that would put your BMI in the healthy band for your height.
The formula
Each formula starts from a base weight at exactly five feet (152.4 cm) and adds a fixed amount for every inch above it:
Devine (1974)
men 50 kg + 2.3 kg per inch · women 45.5 kg + 2.3 kg per inchRobinson (1983)
men 52 kg + 1.9 kg per inch · women 49 kg + 1.7 kg per inchMiller (1983)
men 56.2 kg + 1.41 kg per inch · women 53.1 kg + 1.36 kg per inchHamwi (1964)
men 48 kg + 2.7 kg per inch · women 45.5 kg + 2.2 kg per inchHealthy BMI range
18.5 × height in m² to 24.9 × height in m²Worked example
For a woman of 160 cm, Devine gives 45.5 + 2.3 × 3.0 = 52.4 kg, with a healthy BMI range of 47.4–63.7 kg. At 150 cm, just under five feet, Devine gives 43.3 kg — a rougher figure, because the formula is being stretched below its base height.
When to use it, and the mistakes to avoid
Use it for a rough target when planning to lose or gain weight, to sense-check a goal, or to see how the classic formulas compare with the BMI range.
The mistakes that cost the most:
- Treating one number as the target. The four formulas already disagree by a few kilograms; aim for the healthy range, not a single figure.
- Ignoring muscle and frame. Athletes and people with a large build can be healthy well above these weights.
- Using it for children or in pregnancy. The formulas are for adults only.
- Typing height in the wrong unit. 5.9 is not 5 ft 9 in — use the feet and inches boxes.
- Relying on it below five feet. The formulas were not built for it; lean on the BMI range.
FAQ
What is my ideal weight for my height?
For a man of 175 cm (5 ft 9 in), the Devine formula gives 70.5 kg, and the other three formulas give 68.7 to 72 kg. For a woman of 160 cm (5 ft 3 in), Devine gives 52.4 kg. The healthy BMI range is wider: 56.7 to 76.3 kg at 175 cm, and 47.4 to 63.7 kg at 160 cm.
Which ideal weight formula is the most accurate?
None is exact for any one person - they are estimates for a medium frame. The Devine formula (1974) is the one most used in medicine, for example to work out some drug doses. Robinson and Miller (both 1983) were later refinements, and Hamwi (1964) is the oldest. Where they disagree, the spread is a fair picture of how uncertain the idea of one ideal weight is.
Is ideal weight the same as a healthy weight?
Not quite. The formulas give one number; a healthy weight is a range. The WHO counts a BMI of 18.5 to 24.9 as healthy for adults, which at 175 cm is anything from 56.7 to 76.3 kg. The ideal weight figures usually sit inside that range.
Why do men and women get different ideal weights?
The formulas start from a different base weight at five feet - 50 kg for men and 45.5 kg for women in Devine's - because at the same height men tend to carry more bone and muscle.
Does this work for people under five feet?
The formulas were written for heights of five feet and over. Below that, the same line is extended downwards, which is how they are applied in practice, but the result is a rougher guide. The healthy BMI range works at any adult height and is the better guide there.
Does ideal weight account for muscle or body frame?
No. A muscular person or someone with a large frame can be healthy well above these figures. They also do not apply to children, or during pregnancy. For a personal target, talk to a doctor or dietitian.