Ideal Weight Calculator

What Is "Ideal Weight," Really?

Ideal body weight (IBW) is a reference point — not a verdict. It's the weight that, on average, has been associated with the lowest health risk for a person of your height and sex. Doctors and dietitians use it to estimate medication doses, set initial calorie targets, and give patients a ballpark of where a healthy weight might sit.

The catch is that no single number fits everyone. Muscle, bone density, frame size, and body fat distribution all shift where your own healthiest weight lands. That's why this calculator runs five different formulas and shows you the whole range, not just one answer.

The Five Formulas, Explained

Each formula below estimates ideal weight from height and sex, but they were built from different data:

• Robinson (1983) — derived from US life-insurance data, and still one of the most commonly referenced in clinical settings.
• Miller (1983) — a revision that slightly lowered the base weights from Robinson's original figures.
• Devine (1974) — created for drug dosing, but it became the default in many medical textbooks.
• Hamwi (1964) — one of the oldest, originally developed for calculating ideal weight in adults.
• Peterson (2016) — the newest, and the only one tied to a target BMI of 22, which modern research suggests carries the lowest mortality risk.

How to Read Your Result

The calculator shows you the full spread from the lowest to the highest formula, plus a recommended median. If your current weight is well above the range, that's a signal worth discussing with a professional — but the range itself is a guideline, not a hard boundary. Frame size matters: a naturally broad-shouldered person can sit above the formulas and still be perfectly healthy.

For a more complete picture, pair this with your BMI and body fat percentage. Ideal weight ignores muscle mass, so an athlete can look "overweight" by these formulas while carrying very little fat.

FAQ

Which ideal weight formula is most accurate?

No single formula is universally accurate, which is why this calculator averages five. Robinson and Miller are the most widely cited for adults, while Peterson (which uses a target BMI of 22) tends to align best with modern health guidelines.

Is ideal weight the same as a healthy BMI weight?

Close, but not identical. BMI defines a healthy range as 18.5 to 24.9, which spans a wide band of weights for any given height. Ideal weight formulas aim for a single midpoint, so they usually fall inside the healthy BMI range.

Why do the five formulas give different results?

Each formula was developed from a different study population and uses a different base weight plus a different slope per inch of height. The differences are usually small — a few kilograms — so the range and median matter more than any single number.