What is an ideal weight calculator?
An ideal weight calculator applies height-based equations historically used as reference values in medicine and nutrition. This tool compares four commonly cited formulas rather than presenting one estimate as exact.
The phrase “ideal weight” can be misleading. Health cannot be determined from height and a formula alone, and an appropriate body weight depends on body composition, medical history, age, goals, and other individual factors.
How does this calculator work?
Each formula begins with a base weight at 5 feet and adds a formula-specific amount for every inch above 5 feet. Metric height is converted to inches for the equations, then the results are displayed in the selected unit system.
The calculator also reports the average, the difference between the highest and lowest estimates, a BMI 22 reference, and the adult healthy-BMI weight interval used by the BMI calculator.
Reference-weight formulas used
Robinson: male 51.65 kg + 1.85 kg/in; female 48.67 kg + 1.65 kg/in
Miller: male 55.7 kg + 1.39 kg/in; female 53.0 kg + 1.33 kg/in
Hamwi: male 106 lb + 6 lb/in; female 100 lb + 5 lb/in
“Per inch” means each inch above 5 feet. Formula versions can differ slightly across references because some coefficients are rounded.
How to use the ideal weight calculator
- Choose U.S. Customary or Metric units.
- Select the sex coefficient used by the formulas.
- Enter a height of at least 5 feet or 152.4 centimeters.
- Select Calculate Reference Weight.
- Compare all four formulas, the average, formula spread, and healthy-BMI interval.
Understanding the results
Differences between the formulas are expected. They were developed for different purposes and do not maintain one constant BMI across all heights. The average is a convenient summary only; it is not more medically valid because it combines several equations.
The healthy-BMI interval is calculated from BMI 18.5 through 24.9. BMI is a screening measure and does not directly measure muscle or fat; a body fat calculator uses different measurements and has its own limitations.
Limitations and appropriate use
These formulas do not account for frame size, muscularity, ethnicity, disability, pregnancy, age-related body-composition changes, or an individual's medical context. Most were developed decades ago for clinical reference or drug-dosing discussions, not personal appearance goals.
A registered dietitian or qualified clinician can evaluate weight in a broader health context when a personalized target is necessary.
Frequently asked questions about ideal weight
Sources and methodology
The formulas and limitations are documented with original research and review literature.