Ideal Weight Calculator
Compare the four clinical formulas for ideal body weight — Robinson, Miller, Devine and Hamwi — against a BMI 22 target and the healthy BMI range for your height. Metric and imperial units are both supported.
These formulas were written for adults at least 5 ft tall, and none of them is a target weight — Devine's version was built for drug dosing, not for how anyone should look. The BMI 18.5–25 range is the reference that matches population health data best; treat any single formula as a rough midpoint inside it.
Formula and calculation
Worked example
A 180 cm man is 70.87 inches tall, which is 10.87 inches over the 5 ft base. Robinson gives 52 + 1.9 × 10.87 = 72.6 kg, Miller 71.5 kg, Devine 75.0 kg and Hamwi 77.3 kg — an average of 74.12. The BMI 22 target for 1.80 m is 71.28, and the healthy range for that height runs from 59.94 to 81.
A range beats a single number
At 180 cm the four formulas span almost 5 kg, and at 250 cm they span more than 40 kg — that gap is the honest measure of how much these equations know. They were fitted on specific populations decades ago, mostly to standardize drug doses, and none of them can see muscle, bone structure or where you carry fat. Two people with the same height can both be healthy 15 kg apart. Use the healthy BMI range as the decision band, use BMI 22 as a rough center point if you want a target, and treat any single formula as one opinion among four.
What the results mean
- Average of the four formulas
- The average of the four formulas, in kilograms. It is the closest thing to an answer this page can give — the four disagree by several kilograms at every height, and none of them is more correct than the others.
- BMI 22 target
- The weight that puts you at a BMI of exactly 22, in kilograms. BMI 22 sits near the middle of the healthy range (18.5–25), where population studies find the lowest risk, so it is a useful single target when you want one number.
- Robinson (1983)
- Ideal body weight from the Robinson formula (1983), in kilograms. Robinson and Miller revised the older equations against insurance-company data, so they read higher than Devine at tall heights.
- Miller (1983)
- Ideal body weight from the Miller formula (1983), in kilograms. It gives the highest figures of the four at very tall heights, because it adds 1.41 kg per inch for men.
- Devine (1974)
- Ideal body weight from the Devine formula (1974), in kilograms — the one most hospitals and pharmacy references use, and the reason "ideal body weight" appears in medicine at all: it was written for drug dosing.
- Hamwi (1964)
- Ideal body weight from the Hamwi formula (1964), in kilograms. It adds the most per inch but starts from the lowest base weight, so it runs low in short people and high in tall people.
- Average in pounds
- The same four-formula average in pounds.
- Healthy range floor
- The bottom of the healthy weight range for your height, in kilograms — a BMI of 18.5. Anything above it is inside the healthy band.
- Healthy range ceiling
- The top of the healthy weight range for your height, in kilograms — a BMI of 25.
- Range floor in pounds
- The bottom of the healthy range in pounds.
- Range ceiling in pounds
- The top of the healthy range in pounds.
Frequently asked questions
What is a healthy weight for my height?
The healthy range is a BMI of 18.5 to 25, which this page converts into kilograms and pounds for your height. At 170 cm that is roughly 53–72 kg (118–159 lb); at 180 cm it is about 60–81 kg (132–179 lb). Anywhere inside the band is a reasonable place to be.
Why do the four formulas give different answers?
They were derived from different datasets in different decades, so each one carries its own bias — Miller reads highest in tall people, Hamwi spreads the most across heights, and Devine sits in the middle for short people and low for tall ones. Researchers compare them by asking which formula best predicts a BMI of 21–23 at average heights; none wins everywhere.
Is ideal weight different for men and women?
Yes. Every formula uses a lower base weight for women at the same height, because women carry more essential fat and less muscle on average. The healthy BMI range, by contrast, uses the same 18.5–25 thresholds for both sexes — so the formulas and the BMI range will never agree exactly.
Is this the number hospitals use?
In medicine, "ideal body weight" usually means the Devine formula, because it was written in 1974 for calculating drug doses — some drugs distribute through lean tissue, so dosing follows this estimate rather than your actual weight. It was never intended as a fitness target, which is why it can look low for muscular people.
Does ideal weight account for muscle?
No. All four formulas use height and sex only. A trained athlete can sit above the ideal-weight figure and be leaner than someone at it, because muscle weighs more than fat for the same volume. If you train seriously, body-fat percentage and waist measurement tell you more than any ideal-weight equation.