What Is Your Ideal Weight?
"Ideal weight" is a surprisingly tricky concept. Unlike height or age, there is no single number that is universally "right" for a person of a given height. Body composition, bone density, muscle mass, frame size, and genetics all influence what a healthy weight looks like for any individual. That said, several formulas have been developed over the years to provide reasonable estimates of a healthy weight range based on height and sex.
Four Popular Ideal Weight Formulas
1. Devine Formula (1974)
The Devine formula is the most widely used ideal body weight formula, often cited by physicians and pharmacists for medication dosing calculations.
2. Robinson Formula (1983)
Developed as a modification to the Devine formula, Robinson proposed slightly different coefficients.
3. Miller Formula (1983)
Published alongside the Robinson formula in the same 1983 paper, Miller's version differs further in its baseline and coefficient.
4. Hamwi Formula (1964)
The oldest formula still in common use, the Hamwi equation was originally developed for calculating medication dosages, not for general health purposes.
Why Do the Formulas Give Different Answers?
None of these formulas is "correct" in an absolute sense. They were all developed from different datasets and for different purposes. The 10–15% difference between the highest and lowest estimate is within the normal range of healthy body weight for most people.
This variation highlights an important truth: ideal weight is a range, not a single number. A healthy adult of a given height can have a "normal" weight spanning 15–25 pounds depending on body composition, frame size, and fitness level.
BMI vs Ideal Weight Formulas
Body Mass Index (BMI) is the most commonly used population-level screening tool for weight status. A BMI between 18.5 and 24.9 is classified as "normal weight." The BMI healthy weight range is typically broader than what the ideal weight formulas suggest, particularly at taller heights.
Both approaches share the same limitation: they do not account for body composition. A muscular athlete with 15% body fat can have a BMI in the "overweight" or even "obese" range, while someone with a normal BMI can have a high body fat percentage (sometimes called "skinny fat").
Frame Size Matters
The ideal weight formulas were developed using average frame sizes, but people vary significantly in bone structure and body frame. A person with a large frame naturally weighs more than someone with a small frame at the same height.
A simple way to estimate your frame size is the wrist measurement test: wrap your thumb and middle finger around the smallest part of your wrist. If your fingers overlap, you have a small frame; if they just touch, medium frame; if they do not touch, large frame. Your ideal weight may shift by 5–10% depending on your frame size.
What Really Matters for Health
Focusing too narrowly on a specific number on the scale can be counterproductive. Research consistently shows that fitness level, body composition, and metabolic health markers are better predictors of long-term health outcomes than weight alone.
Instead of chasing an "ideal" number, consider focusing on:
- How you feel: Energy levels, mobility, sleep quality
- Strength and fitness: Can you do the things you want to do?
- Health markers: Blood pressure, blood sugar, cholesterol
- Body composition: Waist circumference, how clothes fit
- Sustainability: Are your habits ones you can maintain?
Frequently Asked Questions
Which ideal weight formula is most accurate?
The Devine formula is the most widely cited and commonly used, particularly in medical settings for drug dosing. But no formula is perfectly accurate for every individual. Use these estimates as a starting point and reference range, not as a strict target.
Do these formulas apply to athletes?
No. Athletes, especially those who strength train regularly, often weigh significantly more than these formulas suggest while having low body fat and excellent health markers. Muscle is denser than fat and weighs more per unit of volume.
Should I aim for the low end or high end of the range?
It depends on your body type, goals, and health. If you have a small frame, naturally lighter bone structure, or are aiming for athletic leanness, the lower end may be appropriate. If you have a larger frame or significant muscle mass, the higher end is likely healthier. When in doubt, work with a healthcare provider who can assess your overall health, not just your weight.