How the Ideal Weight Calculator Works
Understanding Ideal Body Weight and How to Find Yours
The concept of an "ideal" body weight (IBW) fills popular culture, largely driven by media portrayals. However, medical history reveals that IBW was originally created to calculate medication dosages rather than dictate how a person should look. While sports organizations also use weight classifications today, these metrics have strict limitations. Because formulas do not account for muscle mass or body fat percentage, a physically fit athlete might mistakenly register as overweight. Ultimately, weight is not an exact science, and lifestyle choices like eating unprocessed foods, exercising, and resting carry far more weight regarding health than chasing a specific number.
Chart: four formulas for the same man
A man who is 180 cm tall (the default example). The four formulas give a spread of about 6 kg, so treat the answer as a range. The healthy BMI range for this height is 59.9 to 81.0 kg:
Miller █████████████████████████████████████ 71.5 kg Robinson ██████████████████████████████████████ 72.6 kg Devine ███████████████████████████████████████ 75.0 kg Hamwi ████████████████████████████████████████ 77.3 kg
Chart: the Devine formula by height
For a man, each extra inch of height over 5 feet adds 2.3 kg. Taller means a higher ideal weight:
160 cm ███████████████████████████ 56.9 kg 170 cm ███████████████████████████████ 65.9 kg 180 cm ████████████████████████████████████ 75.0 kg 190 cm ████████████████████████████████████████ 84.0 kg
Key Determinants of Weight
Several variables influence what constitutes a healthy weight for an individual:
Age: Growth generally stops by mid-adolescence, but aging naturally brings a reduction in muscle mass and an increase in fat storage.
Gender: Men typically weigh more than women due to higher muscle mass, greater bone density, and taller average heights, despite women having a higher natural body fat percentage.
Height: Taller individuals naturally carry more body mass, with males generally weighing 10 to 20 percent more than females of equivalent height.
Body Frame Size: Wrist circumference relative to height determines whether someone is small, medium, or large-boned, which directly affects natural weight.
Additional Elements: Underlying health conditions, genetics, and how fat is distributed across the body also play significant roles.
Common Formulas for Calculating Ideal Weight
Most IBW formulas share a standard framework: they establish a baseline weight for a height of five feet and add a specific increment for every inch beyond that.
Hamwi Formula (1964):
| Male: | 48.0 kg + 2.7 kg per inch over 5 feet |
| Female: | 45.5 kg + 2.2 kg per inch over 5 feet |
Devine Formula (1974):
| Male: | 50.0 kg + 2.3 kg per inch over 5 feet |
| Female: | 45.5 kg + 2.3 kg per inch over 5 feet |
Robinson Formula (1983):
| Male: | 52 kg + 1.9 kg per inch over 5 feet |
| Female: | 49 kg + 1.7 kg per inch over 5 feet |
Miller Formula (1983):
| Male: | 56.2 kg + 1.41 kg per inch over 5 feet |
| Female: | 53.1 kg + 1.36 kg per inch over 5 feet |
The Role of Body Mass Index (BMI)
BMI range of 18.5 to 25Aside from specific formulas, the World Health Organization identifies a healthy for adults. Doctors frequently use BMI as a screening tool to assess potential risks for conditions like heart disease and diabetes. For children and adolescents aged 2 to 20, medical professionals rely on CDC growth charts, aiming for a BMI situated between the 5th and 85th percentiles.
Important Note: General formulas and BMI metrics are broad tools rather than absolute rules. Because they only factor in height and gender while ignoring body composition or physical uniqueness, they serve best as general guidelines rather than strict targets.