How to use the ideal weight calculator
- Choose the sex used by the formulas and US or metric units.
- Enter your height. Heights between 140 and 230 cm (about 4 ft 7 in to 7 ft 6 in) are accepted.
- Read the Devine and Hamwi formula results and the weight range for BMI 18.5 up to 25 at your height.
- Treat all three as reference points, not goals. They do not know your muscle, frame, age or health.
Formula
Devine, male: 50 kg + 0.9 kg x (height in cm - 152)
Devine, female: 45.5 kg + 0.9 kg x (height in cm - 152)
Hamwi, male: 48 kg + 1.1 kg x (height in cm - 152)
Hamwi, female: 45.4 kg + 0.9 kg x (height in cm - 152)
BMI range: weight = BMI x (height in meters)^2, using 18.5 and 25
The formulas are applied exactly as printed in the cited reference, which gives them per centimeter above 152 cm (5 ft). Pounds use 1 lb = 0.45359237 kg.
Worked example
For a male who is 180 cm tall, Devine gives 50 + 0.9 x 28 = 75.2 kg and Hamwi gives 48 + 1.1 x 28 = 78.8 kg.
At 180 cm, BMI 18.5 is 59.9 kg and BMI 25 is 81.0 kg, so the BMI-based healthy range is 59.9 to 81.0 kg.
For a female who is 165 cm tall, Devine gives 45.5 + 0.9 x 13 = 57.2 kg and Hamwi gives 45.4 + 0.9 x 13 = 57.1 kg.
What "ideal" means here
The word ideal is misleading. The Devine formula was introduced in 1974 to help estimate drug clearance in patients, and the other formulas are simple rules based on height. They do not measure health, and they say nothing about muscle, bone structure, age or body composition. That is why this tool shows the output as formula estimates and puts the BMI range, which is a screening tool, next to them.
Why the numbers differ
The three results usually fall within a few kilograms of each other near average heights, but they diverge for tall and short people because the formulas extrapolate in a straight line. The formulas are written for heights above 152 cm (5 ft), and the page warns when your height is below that.
Using the result well
A better question than "what is my ideal weight" is usually "what weight supports my health and daily life". A clinician can help you answer that with blood pressure, labs, fitness and history. For more detail on the BMI part, see the BMI calculator, and for a tape-measure estimate of body composition, the body fat calculator.
Assumptions and limits
- The formulas were fitted for adults and use only height and sex. Age, muscle, frame and health are not used.
- Sex-specific coefficients are chosen by the sex setting. The tool does not infer anything about gender identity.
- Heights below 152 cm are extrapolated and may be unreliable. Heights outside 140 to 230 cm are rejected.
- BMI range uses the CDC adult cutoffs of 18.5 up to 25.
- Information only. Not medical advice or a diagnosis. Nothing you enter leaves your browser.
Frequently asked questions
What is my ideal body weight?
There is no single ideal weight. Formulas such as Devine and Hamwi give reference values from height and sex, while the BMI range gives a span. Your healthiest weight depends on factors that none of these tools can measure.
Which is better, Devine or Hamwi?
Neither is better in a general sense. Devine is more common in clinical settings, while Hamwi is an older rule. They land close together for average heights, which is why both are shown with the BMI range.
Why does the BMI range look so wide?
The healthy BMI category spans 18.5 up to 25, which is a gap of about 20 kg at typical heights. A wide range reflects real differences between healthy bodies, so a single point can be misleading.
Does this work for older adults or athletes?
It can be a rough reference, but muscle mass, bone density and age change what a healthy weight is. For those groups, a body composition check by a professional is more informative.
Why does the page warn about short heights?
The formulas are written for heights above 5 ft (152 cm). Below that they keep extending the same straight line, which can give values that are less meaningful.