Ideal Weight Calculator: Devine, Robinson, Miller and Hamwi

Ideal body weight is the weight an old formula predicts for your sex and height. Four formulas dominate: Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964). Each one starts from a weight at 5 ft and adds a fixed amount for every inch above it. An ideal body weight calculator runs them for you, and some sites call the same tool a desired weight calculator.

Most calculators pick one formula and print it as if it were a measurement. This one shows all four side by side, reports the spread between them as a range, and puts the BMI 18.5 to 24.9 range for your height beside it as a comparison. Add your current weight and the card tells you where you sit, in plain numbers.

How to calculate ideal body weight

All four formulas work the same way, so you can run any of them by hand in four steps.

1. Find your inches over 5 ft. Take your height in inches and subtract 60. Someone who is 5 ft 5 in has 5 inches over 5 ft. If you know your height in centimeters, divide by 2.54 first: 165.1 cm is 65 inches.
2. Multiply by the formula's amount per inch. The Devine formula adds 2.3 kg per inch for women and men, so 5 inches add 11.5 kg.
3. Add the formula's starting weight at 5 ft. Devine starts women at 45.5 kg and men at 50 kg, so the 5 ft 5 in woman gets 45.5 + 11.5 = 57.0 kg, which is 126 lb.
4. Repeat for the other formulas and take the lowest and highest. For the same woman, Robinson gives 56.9 kg (125 lb), Miller gives 59.9 kg (132 lb) and Hamwi gives 100 + 5 × 5 = 125 lb. Her range is 125 to 132 lb.

For a man who is 5 ft 10 in, the same steps give 161 lb from Devine (50 + 2.3 × 10 = 73.0 kg), 155 lb from Robinson, 155 lb from Miller and 166 lb from Hamwi (106 + 6 × 10). His range is 155 to 166 lb. To convert, 1 kg is 2.2046 lb.

The four ideal body weight formulas, side by side

Each formula below has a version for women and one for men, written as a starting weight at 5 ft plus a fixed amount for each inch over 5 ft (n). Devine, Robinson and Miller work in kilograms; Hamwi works in pounds. The coefficients for Devine, Miller and Hamwi are as reprinted in Table 3 of Peterson et al. (2016) in the American Journal of Clinical Nutrition. The Robinson coefficients come from the abstract of the original paper.

We checked the Robinson numbers against the original abstract, which gives 51.65 kg plus 1.85 kg per inch for men and 48.67 kg plus 1.65 kg per inch for women. The rounded version most sites use adds about 1 to 2.5 lb, so this calculator can read a pound or two below others on that row. We could not open the full Miller letter or Hamwi's chapter, which is not online, so those coefficients are as Peterson et al. print them; a 2025 Delphi study on nutrition after spinal cord injury in Nutrients (Zengul et al.) gives the same Hamwi numbers. Some websites quote Hamwi as 110 lb plus 5 lb per inch for men, which is not the published rule.

Ideal weight for my height: a chart for women and men

This chart runs all four formulas for heights from 4 ft 10 in to 6 ft 4 in and gives the lowest and highest result for each sex. The last column is the BMI 18.5 to 24.9 range for the same height, which is the same for women and men. The BMI calculator covers BMI in full.

At every height the BMI range is several times wider than the formula range, and the formula range sits in its lower half. That is the first sign that the formulas describe one narrow idea of a typical build, not the whole range of weights that people stay healthy at.

Ideal weight calculator for men and women: how the formulas differ

The women's versions start lower at 5 ft and, except for Devine, add less weight per inch. Devine keeps a fixed gap of 4.5 kg (about 10 lb) between men and women at every height. Hamwi's gap grows with height, from 6 lb at 5 ft to 18 lb at 6 ft, because it adds 6 lb per inch for men and 5 lb for women.

Which formula gives the highest number depends on your height. For a woman up to about 5 ft 8 in, Miller is the highest, because it starts women at 53.1 kg, well above the others, and climbs slowly. For a tall man, Hamwi is the highest and Miller the lowest: at 6 ft 4 in they are 202 lb and 174 lb, 28 lb apart. In the middle of the height range, from 5 ft 4 in to 5 ft 8 in, the four agree within 5 to 9 lb for both sexes.

Peterson and colleagues worked out which BMI each formula follows most closely. The men's versions follow a BMI of 22.5 to 23.4 and the women's versions 21.0 to 21.7. No health study asked for that gap between the sexes; it was inherited from the tables and rules the formulas were fitted to.

How accurate is this ideal weight calculator?

The calculator runs the four formulas exactly. Whether the formulas themselves are accurate is a harder question, because none of them was built to answer it. Pai and Paloucek (2000), who traced their history in the Annals of Pharmacotherapy, describe how they grew out of insurance height-weight tables: weights that went with lower death rates among policyholders came to be called desirable, and then ideal. Devine's 1974 equations matched an older rule of thumb drawn from those tables, and later regressions on the tables produced nearly the same lines. Robinson and colleagues (1983) concluded that the widely used rule probably contained only minor errors, but they measured it against the same insurance tables. None of the four was compared with body fat scans or checked against who stayed healthy.

The tables themselves were never a universal standard. As Harrison (1985) wrote in the Annals of Internal Medicine, the lowest-risk weight changes from one population to another, over time and by cause of death, so it cannot be pinned down for a person who differs from the people the tables were built on.

The only published accuracy figures measure something narrower: how closely each formula follows a single BMI from 5 ft to 6 ft 3 in. Peterson et al. found the BMI each formula tracks best and the average error against it.

Peterson et al. tested Robinson in the rounded form, 52 + 1.9n for men and 49 + 1.7n for women. An error of 3 percent is about 4 to 6 lb at these weights. The error is not spread evenly, though. Shah, Sucher and Hollenbeck (2006) plotted the formulas against BMI and found they land near a BMI of 20 for short people and near 25 for tall people. They concluded that Robinson fit men best, that no formula came close to a BMI of 22 for women, and that BMI ranges were more useful in practice. You can see the same drift on this page: the four formulas agree within 5 to 9 lb in the middle of the height range, then spread to 17 lb for a 5 ft woman and 28 lb for a 6 ft 4 in man.

So the honest answer is that the range on the card tells you what four old formulas say about an average build of your height, give or take the few pounds they disagree by. It cannot tell you whether your own weight is healthy, because it never sees what that weight is made of.

Why muscular people land above the range

Muscle, bone and body water all count on the scale, and the formulas assume an average build. Peterson et al. point out that anything tied to BMI shares its blind spot: it misclassifies very muscular people. A man who is 6 ft 2 in and lifts several times a week might weigh 215 lb. He sits 25 lb above the highest formula and at a BMI of 27.6, and neither number can tell whether the extra weight is muscle or fat. A body fat estimate can. The body fat calculator estimates it with a tape measure, and the lean body mass calculator shows how much of a body weight is not fat.

Why older adults often land above it, and why that can be fine

The formulas do not change with age at all, but the evidence on weight and survival does. In a meta-analysis of 32 studies with 197,940 adults aged 65 and over, Winter et al. (2014) found the risk of death was 12 percent higher at a BMI of 21.0 to 21.9 and 19 percent higher at 20.0 to 20.9 than at 23.0 to 23.9. Risk did not start to rise until a BMI above 33. The women's formulas follow a BMI of about 21, which is in the band that study linked with higher risk after 65. If you are an older adult who weighs more than the formula range, that is not by itself a reason to lose weight. Unplanned weight loss at that age is worth raising with a doctor.

Heights under 5 ft

All four formulas start at 5 ft, and Peterson et al. state the equations for heights of 60 inches and over. Below 5 ft, the inches over 5 ft turn negative, and the authors never said what to do there. This calculator extends each straight line downward by the same amount per inch, marks the rows in amber and says so on the card. It stops at 4 ft 6 in137 cm.

The extended lines show the formulas breaking down. For a woman who is 4 ft 10 in, Devine and Hamwi give 90 lb, a BMI of 18.8, while Miller gives 111 lb. At 4 ft 8 in, Devine and Hamwi drop to 80 lb, a BMI of 17.9, which is under the 18.5 line. Below 4 ft 6 in the calculator shows no result and points you to the BMI range instead. If you are under 5 ft, treat the BMI row on the card as the steadier reference.

Worked examples: four formulas for eight people

Eight people run through the calculator. Three add their current weight, so the last column also says where they sit.

Three patterns stand out. The spread is smallest near the middle of the height range, 5 lb for the 5 ft 6 in man and the 5 ft 8 in woman, and largest at the ends: 17 lb for the 5 ft woman and 28 lb for the 6 ft 4 in man. The 5 ft 8 in woman at 165 lb and the 5 ft 10 in man at 180 lb both sit just over a BMI of 25 and well above the formula range, which says nothing about how much of their weight is muscle. And the 4 ft 10 in woman's lowest formulas almost touch the bottom of the BMI range, the breakdown described above.

Body frame size and ideal weight

Frame size is the idea that people with heavier bones and broader builds should weigh more at the same height. The insurance tables behind the formulas listed separate weights for small, medium and large frames, and Robinson et al. (1983) fitted separate equations for each frame size as well as the all-frames version this calculator uses.

Measuring frame is the hard part. Frisancho and Flegel (1983) tested candidate measures in 16,494 US adults and chose elbow breadth, because it was the least tied to body fat and changed little with age. Frisancho (1984) then published weight standards by height, sex and frame size from 21,752 adults aged 25 to 74 in two national health surveys. At home, people often wrap a thumb and middle finger around the opposite wrist as a rough check: fingers that overlap suggest a small frame, and fingers that do not meet suggest a large one.

A common dietetics rule adds 10 percent to the Hamwi result for a large frame and takes 10 percent off for a small one. Hamwi's 1964 chapter is not online, so we could not check that rule against the source, and this calculator does not apply it. If you have a broad build, read the top of the formula range, or the BMI row, as the closer reference.

A better question: what is your weight made of?

Two people at the same height and weight can have very different amounts of muscle and fat, and that difference matters more for health than where either sits against a height formula. These tools answer it more directly:

• Body fat. The body fat calculator estimates body fat percentage from tape measurements or skinfolds, with the error range of each method.
• Lean mass. The lean body mass calculator shows how much of your weight is muscle, bone, organs and water.
• BMI. The BMI calculator gives your BMI and its categories, with the same limits for muscular builds.

If you do decide to change your weight, pick a pace you can keep. The weight loss date calculator estimates when you could reach a goal weight at a steady rate, and our comparison of the best workout apps for weight loss looks at which ones build strength training into the plan, so more of what you lose is fat rather than muscle.

Why hospitals still use ideal body weight

Clinicians still use ideal body weight, mostly as a stand-in for lean body mass. Devine wrote his formula for dosing gentamicin, and Pai and Paloucek note that the way some drugs move through the body was found to track ideal body weight, which is how Devine's equations came into wide use. Peterson et al. list drug dosing, judging overweight and underweight, and working out nutrient needs as the uses that remain.

Intensive care is the other place you will meet it. The ARDS Network study (2000) set ventilator breath size at 6 mL per kilogram of predicted body weight and found lower mortality than with larger breaths. The predicted body weight formula printed in later ventilation studies, such as Sinnige et al. (2025), is 50 + 0.91 × (height in cm − 152.4) for men and 45.5 + 0.91 × (height in cm − 152.4) for women. That is the Devine formula written in centimeters. These are clinical decisions for your care team; this page is not for dosing or ventilator settings.

When to ignore this calculator

The formulas describe an average adult build. In the cases below, skip the number or ask a clinician.

• Children and teenagers. The calculator is for adults 18 and over. Children are judged on growth charts for their age. Ask a pediatrician.
• Pregnancy and the months after birth. Healthy weight gain in pregnancy has its own targets. Your obstetric care team is the right source.
• Eating disorders or recent recovery. A single target weight can work against recovery. Work with a clinician or dietitian who specializes in eating disorders.
• Adults over 65 or with unplanned weight loss. The formulas sit low for this age group, as the section above explains. Talk to your doctor before trying to lose weight, and mention any weight loss you did not plan.
• Drug dosing and ventilator settings. Hospitals use versions of these formulas for both. Those decisions belong to your care team.
• Very muscular builds. The formulas cannot see muscle and will put you above the range. Use a body fat estimate instead.

Related reading

References

1. Devine BJ. "Gentamicin therapy." Drug Intell Clin Pharm. 1974;8:650-655, in the column "Clinical Pharmacy: Case Studies." doi:10.1177/106002807400801104
2. Robinson JD, Lupkiewicz SM, Palenik L, Lopez LM, Ariet M. "Determination of ideal body weight for drug dosage calculations." Am J Hosp Pharm. 1983;40(6):1016-1019. doi:10.1093/ajhp/40.6.1016, PubMed 6869387
3. Miller DR, Carlson JD, Lloyd BJ, Day BJ. "Determining ideal body weight (and mass)." Am J Hosp Pharm. 1983;40(10):1622, 1625. doi:10.1093/ajhp/40.10.1622a, PubMed 6638023. Coefficients as reprinted in Peterson et al. 2016.
4. Hamwi GJ. "Therapy: changing dietary concepts." In: Diabetes Mellitus: Diagnosis and Treatment. New York: American Diabetes Association; 1964:73-78. Not online; coefficients as reprinted in Peterson et al. 2016 and Zengul et al. 2025.
5. Pai MP, Paloucek FP. "The origin of the 'ideal' body weight equations." Ann Pharmacother. 2000;34(9):1066-1069. doi:10.1345/aph.19381, PubMed 10981254
6. Peterson CM, Thomas DM, Blackburn GL, Heymsfield SB. "Universal equation for estimating ideal body weight and body weight at any BMI." Am J Clin Nutr. 2016;103(5):1197-1203. doi:10.3945/ajcn.115.121178, PMC4841935
7. Shah B, Sucher K, Hollenbeck CB. "Comparison of ideal body weight equations and published height-weight tables with body mass index tables for healthy adults in the United States." Nutr Clin Pract. 2006;21(3):312-319. doi:10.1177/0115426506021003312
8. Harrison GG. "Height-weight tables." Ann Intern Med. 1985;103(6 Pt 2):989-994. doi:10.7326/0003-4819-103-6-989
9. Winter JE, MacInnis RJ, Wattanapenpaiboon N, Nowson CA. "BMI and all-cause mortality in older adults: a meta-analysis." Am J Clin Nutr. 2014;99(4):875-890. doi:10.3945/ajcn.113.068122
10. Frisancho AR, Flegel PN. "Elbow breadth as a measure of frame size for US males and females." Am J Clin Nutr. 1983;37(2):311-314. doi:10.1093/ajcn/37.2.311
11. Frisancho AR. "New standards of weight and body composition by frame size and height for assessment of nutritional status of adults and the elderly." Am J Clin Nutr. 1984;40(4):808-819. doi:10.1093/ajcn/40.4.808
12. Acute Respiratory Distress Syndrome Network. "Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome." N Engl J Med. 2000;342(18):1301-1308. doi:10.1056/NEJM200005043421801
13. Sinnige JS, Smit MR, Alam MJ, et al. "Personalized mechanical ventilation guided by lung ultrasound in patients with ARDS." Intensive Care Med Exp. 2025;13(1):135. doi:10.1186/s40635-025-00835-8
14. Zengul AG, Ferguson CC, Rimmer JH, et al. "Expert-reviewed nutritional guidance for adults with spinal cord injury: a Delphi study." Nutrients. 2025;17(9):1520. doi:10.3390/nu17091520

How this calculator differs from typical ideal weight calculators

Most online ideal weight calculators run one formula, usually Devine, and print a single weight as if it were a measurement. Others list several formulas without saying what each was written for, round the Robinson coefficients, or quote Hamwi's rule with the wrong numbers. Few say that none of the formulas was checked against body fat or health, or what happens below 5 ft.

This calculator runs the four published formulas side by side and reports the spread between them as a range, with the BMI each result works out to. It uses Robinson's coefficients as published, checks every other coefficient against a reprint, and shows the BMI 18.5 to 24.9 range for your height as a comparison row. Your weight is optional, and when you add it the card says where you sit in plain numbers. Heights under 5 ft are extended and flagged rather than hidden, and no number appears until height and weight sit inside realistic adult ranges.