What ideal weight formulas actually are
There is no single ideal weight for a given height. The formulas on this page were created by doctors to estimate a reference weight for calculating drug doses and kidney function, not to tell anyone how they should look.
They are still a useful sense check, especially when shown together and next to the healthy BMI range. Where they cluster gives you a reasonable picture of a typical healthy weight for an average build at your height.
How to use the calculator
Choose your sex and enter your height in centimetres or feet and inches. The calculator returns the result from each of the four formulas and the weight range that keeps your BMI between 18.5 and 24.9.
Weight is not an input, because none of the formulas use it. That is part of their limitation: they ignore your frame and how much muscle you carry.
The four formulas
All four start from a base weight at 5 feet (152.4 cm) and add a fixed amount for every inch above that.
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 kg + 2.3 kg per inch | 45.5 kg + 2.3 kg per inch |
| Robinson (1983) | 52 kg + 1.9 kg per inch | 49 kg + 1.7 kg per inch |
| Miller (1983) | 56.2 kg + 1.41 kg per inch | 53.1 kg + 1.36 kg per inch |
| Hamwi (1964) | 48 kg + 2.7 kg per inch | 45.5 kg + 2.2 kg per inch |
Inches over 5 ft = (height in cm / 2.54) - 60
Healthy BMI range = 18.5 x height(m)² to 24.9 x height(m)²
Example: a man 178 cm (5 ft 10 in) tall gets Devine 73.2 kg, Robinson 71.2 kg, Miller 70.4 kg and Hamwi 75.2 kg. His healthy BMI range is 58.6 to 78.9 kg.
Why the formulas disagree
Each formula came from different data and was tuned for a different purpose. Devine's was a dosing shortcut that spread through medicine without much testing. Robinson and Miller were later attempts to fit it better to actual population data. Hamwi's dates from life insurance tables of the era.
Miller's formula rises slowest with height, so it gives lower numbers for tall people. Hamwi's rises fastest. For very short or very tall people the spread between them can be 10 kg or more, which shows how rough these estimates are.
Who these numbers do not suit
- People who lift. Muscle is dense. A well-trained lifter can be 10-15 kg over every formula here and still be lean and healthy.
- Larger or smaller frames. None of the formulas adjust for bone structure.
- Very short or very tall people. The linear per-inch method breaks down at the extremes, and the formulas are not meant for anyone under 5 ft.
- Children, older adults and pregnancy. Different references apply.
If your weight is above these numbers but your waist is under half your height and your body fat is in a healthy range, the formulas are not telling you anything useful.
A better target for lifters
If you train, build your goal from body composition instead. Estimate your body fat with the body fat calculator, find your lean mass with the lean body mass calculator, and decide what body fat you want to reach. Then divide lean mass by (1 minus your target body fat as a decimal).
Goal weight = lean mass / (1 - target BF% / 100)
Someone with 65 kg of lean mass aiming for 15% body fat would land at about 76.5 kg. Check your muscularity with the FFMI calculator.
How to use these numbers sensibly
Think of the results as a band rather than a target. The lowest and highest of the four formulas, together with the healthy BMI range, frame where most people of average build and your height feel and function well.
If you are well above that band and do not lift, it is a fair sign that some fat loss would benefit your health. Losing even 5 to 10% of your body weight improves blood pressure, blood sugar and cholesterol for many people, long before you reach any formula's number.
If you are below the band, especially below the BMI range, and have lost weight without trying, speak to a doctor. Unintended weight loss can have medical causes worth ruling out.
For most people, the more useful goals are behaviours rather than a number: training three or four times a week, eating enough protein, walking daily and sleeping seven or more hours. Weight tends to settle somewhere healthy when those are in place.
Next steps
To move toward your chosen weight, find your maintenance with the TDEE calculator and read BMI vs body fat percentage to understand which number to watch. Beginners should pair any weight goal with the beginner gym guide.
Frequently asked questions
Which ideal weight formula is most accurate?
None is accurate for individuals. Robinson and Miller tend to fit modern populations a little better than Devine, but the healthy BMI range is a more practical guide.
Why is my ideal weight lower than my current weight even though I am lean?
The formulas ignore muscle and frame size. Lifters routinely weigh more than them while carrying little fat.
What were these formulas designed for?
Mostly for doctors estimating drug doses and kidney function. They were never intended as aesthetic or fitness targets.
Does ideal weight change with age?
The formulas do not include age. In practice, keeping muscle as you age matters more than hitting a specific number.
Can I use these formulas if I am under 5 feet tall?
They are not designed for heights under 5 ft. Use the healthy BMI range shown by the calculator instead.
References
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655
- Robinson JD, Lupkiewicz SM, Palenik L et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm. 1983;40(6):1016-1019
- Miller DR, Carlson JD, Loyd BJ, Day BJ. Determining ideal body weight (and mass). Am J Hosp Pharm. 1983;40(10):1622-1625
- Pai MP, Paloucek FP. The origin of the 'ideal' body weight equations. Ann Pharmacother. 2000;34(9):1066-1069
Results are estimates for healthy adults and are not medical advice. See our medical disclaimer.
