How to use the Ideal Weight Calculator
- Choose male or female.
- Choose whether you enter your height in centimetres or inches, and enter it.
- Read the result of each formula. They differ a little, so look at the range between them.
- Use the result as a reference only and talk to a doctor about a healthy weight for you.
Formula used
Each formula starts from a base weight at 5 feet (60 in) and adds a fixed number of kg for every inch above. Devine: men 50 kg + 2.3 kg/in, women 45.5 kg + 2.3 kg/in. Robinson: 52 + 1.9 / 49 + 1.7. Miller: 56.2 + 1.41 / 53.1 + 1.36. Hamwi: 48 + 2.7 / 45.5 + 2.2.
Worked example
Here is the Ideal Weight Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Sex | Male |
| Height in | Centimetres |
| Height | 175 |
| Result | |
| Devine formula | 70.5 kg (155.3 lb) |
| Robinson formula | 68.9 kg (151.9 lb) |
| Miller formula | 68.7 kg (151.6 lb) |
| Hamwi formula | 72 kg (158.8 lb) |
The four formulas
Each formula takes a base weight for a person 5 feet (60 inches) tall and adds a fixed amount for every inch above 5 feet. Devine (1974): men 50 kg + 2.3 kg per inch, women 45.5 kg + 2.3 kg per inch. Robinson (1983): men 52 kg + 1.9 kg per inch, women 49 kg + 1.7 kg per inch. Miller (1983): men 56.2 kg + 1.41 kg per inch, women 53.1 kg + 1.36 kg per inch. Hamwi (1964): men 48 kg + 2.7 kg per inch, women 45.5 kg + 2.2 kg per inch.
For a man 175 cm tall (68.9 inches): Devine gives 70.5 kg (155.3 lb), Robinson 68.9 kg (151.9 lb), Miller 68.7 kg (151.6 lb) and Hamwi 72 kg (158.8 lb). For a woman 165 cm tall: Devine 56.9 kg (125.5 lb), Robinson 57.4 kg (126.6 lb), Miller 59.8 kg (131.9 lb) and Hamwi 56.4 kg (124.4 lb).
Why the formulas differ
The formulas were created at different times, from different data and for different purposes. Devine’s was designed to help calculate drug doses, not to define a healthy weight. The others adjusted it using other populations and methods. Because they use different slopes, they diverge more at greater heights.
There is no single correct answer, and a spread of a few kilograms between the formulas is normal. Treat the results as a range.
Limits of the idea
These formulas ignore age, muscle, bone structure and body fat. An athlete with a lot of muscle can weigh more than the formula and be very healthy, and someone with a low muscle mass can weigh the formula weight and have high body fat. They were also built from limited groups of people, so they may fit some populations better than others.
For a broader picture, look at your body mass index, waist measurement and body fat percentage, and at fitness, blood pressure and other health measures. The BMI and body fat calculators on this site can help.
Healthy weight is a range
A healthy weight for your height is a range, not a single number. The BMI range of 18.5 to 24.9 is widely used as a guide for adults, though it is also imperfect. Aim for a weight at which you feel well, have good energy, and can keep your habits without extreme effort.
This tool gives general information and is not medical advice. Speak to a doctor or dietitian before starting a weight-change plan.
Frequently asked questions
Is ideal weight the same as healthy weight?
No. These formulas give a single reference number. A healthy weight is a range and depends on body build, age and muscle mass.
Why do the formulas differ?
They were developed for different purposes and populations, so they give slightly different answers.
Which formula is the best?
None is best. Look at the range across all four rather than relying on one.
Do these formulas work for children?
No. They are meant for adults. For children, use growth charts and ask a paediatrician.
Does muscle change the result?
The formulas do not account for it. A muscular person can weigh more than the formula and still be healthy.
What if I am under 5 feet tall?
The formulas extrapolate below 60 inches, but they are less reliable there. The calculator accepts heights from 4 feet.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.