What is Your True "Ideal" Weight?
If you ask three different doctors what your ideal weight should be, you might get three different answers. That is because "Ideal Body Weight" (IBW) is not a single, magic number; it is a range based on historical medical data. Our Advanced Ideal Weight Calculator compares the four most respected medical algorithms—Robinson, Miller, Devine, and Hamwi—alongside the World Health Organization's BMI standards to give you a comprehensive picture of your health goals.
Why Are There 4 Different Formulas?
Over the last century, researchers have developed different equations to estimate healthy weights for drug dosages and vitality. This calculator computes all of them for you:
- Devine Formula (1974): The most widely used standard in the medical community. It was originally developed to calculate dosages for medications like gentamicin.
- Robinson Formula (1983): A modification of the Devine formula that often provides slightly higher weight targets.
- Miller Formula (1983): developed to correspond more closely to modern weight charts, often resulting in lower ideal weights for shorter people.
- Hamwi Formula (1964): The "Rule of Thumb" formula. It assigns 106 lbs for the first 5 feet, plus 6 lbs for every inch thereafter (for men).
IBW vs. BMI: What is the Difference?
While they are related, they measure different things:
- BMI (Body Mass Index): A broad screening tool that categorizes you as Underweight, Normal, Overweight, or Obese based strictly on the ratio of your weight to height. It does not care about gender.
- IBW (Ideal Body Weight): A more specific target that accounts for gender. Men generally have more muscle mass and heavier bones than women, so their ideal weight calculations are higher for the same height.
The "Muscle Mass" Exception
Important Disclaimer: None of these formulas account for body composition. If you are an athlete or bodybuilder with significant muscle mass, these calculators may label you as "Overweight." Muscle is denser than fat. For athletes, body fat percentage is a far more accurate metric of health than scale weight.
Frequently Asked Questions
Does frame size matter?
Yes. These formulas assume a "Medium" body frame. If you have a Large Frame (thick wrists/ankles), your healthy weight could be 10% higher than the calculated result. If you have a Small Frame, it could be 10% lower.
Which formula should I trust?
For most people, the Devine Formula is considered the gold standard. However, looking at the Healthy BMI Range (usually 18.5 - 25) gives you a broader, more flexible window to aim for rather than stressing over a specific number.
Is this for children?
No. These formulas are strictly for adults (18+). Children and teenagers require specialized growth charts because their bodies are developing rapidly.