Which formula is the most accurate?

The Devine Formula (1974) is the most widely used medically, especially for calculating medication dosages. However, no formula is perfect because none of them account for muscle mass or body composition. For athletes, these formulas often underestimate ideal weight.

Does frame size matter?

Yes. People with larger bone structures (measure your wrist circumference to check) naturally weigh more. Most Ideal Weight formulas assume a 'medium' frame, so small-framed individuals should subtract ~10% and large-framed individuals should add ~10%.

Is 'Ideal Weight' the same as 'Healthy Weight'?

Not necessarily. 'Ideal' is often a statistical average or aesthetic goal. 'Healthy' is a range (like a BMI of 18.5-24.9) where disease risk is lowest. You can be healthy at a weight higher than your 'ideal' formula result.

How do I calculate my frame size?

Wrap your thumb and middle finger around your wrist. If they overlap, you have a small frame. If they just touch, you have a medium frame. If they don't meet, you have a large frame.

The Myth of the 'Perfect' Number

The scale is a tool, not a judge. While "Ideal Body Weight" (IBW) formulas are useful medical benchmarks, they aren't the whole story. Let's dig into the math, the science, and the reality.

Check Your BMI Today

While not perfect, BMI is the standardized starting point for assessing weight category.

Calculate BMI

⚖️

Why Do These Formulas Exist?

Surprisingly, "Ideal Body Weight" formulas were not originally invented for diet culture. They were invented by doctors to calculate drug dosages. Anesthesiologists needed to know how much medicine to give a patient, but using *actual* weight for obese patients could result in a fatal overdose. They needed a formula for "metabolically active tissue," or what the patient *should* weigh.

The Big 4 Formulas

Here are the four heavyweights of the medical world.Note: The "Base" is for a height of 5 feet. You add the variable for every inch over 5 feet.

Formula	Men (Base + Per Inch)	Women (Base + Per Inch)
Devine (1974)	50kg + 2.3kg	45.5kg + 2.3kg
Robinson (1983)	52kg + 1.9kg	49kg + 1.7kg
Miller (1983)	56.2kg + 1.41kg	53.1kg + 1.36kg
Hamwi (1964)	106 lbs + 6 lbs	100 lbs + 5 lbs

Which one is best? The Devine formula is the most widely accepted standard in hospitals. The Miller formula is often criticized for being too low for tall people.

The Missing Variable: Frame Size

The scale measures everything: bone, muscle, fat, water, and organ tissue. If you have a large frame (broad shoulders, thick wrists), you simply have more bone mass. Most formulas result in a single number that assumes a "Medium Frame."

Adjustment Rules:
Small Frame: Subtract 10% from the result.
Large Frame: Add 10% to the result.

How to Determine Frame Size (Wrist Test)

Wrap your thumb and middle finger around your other wrist:

Small Frame: Fingers overlap.
Medium Frame: Fingers just touch.
Large Frame: Fingers do not meet (gap).

A Better Metric: Waist-to-Height Ratio (WHtR)

Because weight is a bad proxy for health (muscle weighs more than fat!), modern medicine is moving toward the **Waist-to-Height Ratio**. This measures *visceral fat* (belly fat), which is the most dangerous type of fat connected to heart disease and diabetes.

The Goal: Your waist circumference should be less than half your height.
Example: If you are 6 feet tall (72 inches), your waist should be under 36 inches.

Conclusion

Do not obsess over hitting a specific number from 1974. Use these formulas as a rough guide, but listen to your body, your doctor, and your blood work. If you are active, eating well, and your markers are good, you are at your ideal weight regardless of what Dr. Devine says.