Ideal Weight Calculator
✦ Health & WellnessThis ideal weight calculator shows the healthy weight range for your height in kg or lb, with the Devine, Robinson, Miller and Hamwi formulas beside it. It answers how much you should weigh with a range, not one number.
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The formula
Healthy-weight range and the four ideal body weight formulas
Healthy range = 18.5 × height (m)² to 24.9 × height (m)² (WHO 2004 Asian cut-offs: to 22.9)
o = height in inches − 60
Devine 1974: men 50 + 2.3 × o kg women 45.5 + 2.3 × o kg
Robinson 1983: men 52 + 1.9 × o kg women 49 + 1.7 × o kg
Miller 1983: men 56.2 + 1.41 × o kg women 53.1 + 1.36 × o kg
Hamwi 1964: men 106 + 6 × o lb women 100 + 5 × o lb (−10 % small frame, +10 % large frame)The range uses the WHO, CDC and NHLBI adult BMI classes. The formulas are as printed by Pai and Paloucek (2000) and, for Hamwi, by the American Diabetes Association. Frame size moves Hamwi only, because only Hamwi defined it. Below 5 ft the formulas subtract their per-inch figure. Conversions use 2.54 cm per inch and 0.45359237 kg per pound; figures are rounded to 0.1 at display.
Calculating it by hand
- Choose male or female, then metric or US units, and enter your height (cm, or feet and inches) and, if you like, your current weight.
- Square your height in metres and multiply by 18.5 and by 24.9 for the healthy range: 1.75² = 3.0625, so 56.7 to 76.3 kg at 175 cm.
- Count the inches over 5 ft: 175 cm is 68.9 in, so o = 8.9.
- Work each formula: a man at 175 cm gets Devine 50 + 2.3 × 8.9 = 70.5 kg, Robinson 68.9 kg, Miller 68.7 kg and Hamwi 106 + 6 × 8.9 = 159.4 lb (72.3 kg).
- Under Advanced, a small or large frame takes 10% off or adds 10% to the Hamwi figure, and the Asian cut-off points end the healthy range at BMI 22.9.
- Read your weight against the range as information: the calculator shows how far it sits from either end, never a target to reach.
Worked examples
A man, 175 cm and 70 kg (metric, the defaults)
Enter: Male, Metric, height 175 cm, weight 70 kg.Healthy range: 1.75² = 3.0625; 18.5 × 3.0625 = 56.7 kg to 24.9 × 3.0625 = 76.3 kg175 cm ÷ 2.54 = 68.9 in, so o = 8.9 in over 5 ftDevine 50 + 2.3 × 8.9 = 70.5 kg; Robinson 52 + 1.9 × 8.9 = 68.9 kg; Miller 56.2 + 1.41 × 8.9 = 68.7 kgHamwi 106 + 6 × 8.9 = 159.4 lb = 72.3 kgYour BMI: 70 ÷ 3.0625 = 22.9, inside the range
Healthy range 56.7–76.3 kg; the four formulas give 68.7–72.3 kg; 70 kg (BMI 22.9) is inside the range
A woman, 5 ft 4 in and 150 lb (US units)
Enter: Female, US units, 5 ft 4 in, weight 150 lb.64 in × 2.54 = 162.56 cm; 1.6256² = 2.6426; 18.5 × 2.6426 = 48.9 kg = 107.8 lb; 24.9 × 2.6426 = 65.8 kg = 145.1 lbo = 4 in: Devine 45.5 + 9.2 = 54.7 kg (120.6 lb); Robinson 49 + 6.8 = 55.8 kg (123.0 lb); Miller 53.1 + 5.44 = 58.5 kg (129.1 lb)Hamwi 100 + 5 × 4 = 120.0 lbYour BMI: 150 lb = 68.0 kg; 68.0 ÷ 2.6426 = 25.7; 150 − 145.1 = 4.9 lb above the upper end
Healthy range 107.8–145.1 lb; formulas 120.0–129.1 lb; 150 lb (BMI 25.7) is 4.9 lb above the upper end, shown as information
A man, 168 cm and 66 kg, Asian cut-off points and a large frame
Enter: Male, Metric, 168 cm, 66 kg; Advanced → BMI cut-off points → Asian, WHO 2004; Frame size → Large.Healthy range on the Asian points: 1.68² = 2.8224; 18.5 × 2.8224 = 52.2 kg to 22.9 × 2.8224 = 64.6 kg168 ÷ 2.54 = 66.14 in, o = 6.14: Devine 64.1 kg, Robinson 63.7 kg, Miller 64.9 kg (0.2 kg above the upper end)Hamwi 106 + 6 × 6.14 = 142.9 lb = 64.8 kg; large frame +10% = 71.3 kg, 6.6 kg above the upper endYour BMI: 66 ÷ 2.8224 = 23.4, 1.4 kg above 64.6 kg
Healthy range 52.2–64.6 kg on the WHO 2004 Asian points; Hamwi with a large frame 71.3 kg; 66 kg (BMI 23.4) is 1.4 kg above the range
Methodology
How ideal weight is worked out
The best-known ideal weight formula was published in 1974 to dose an antibiotic, not to say what anyone should weigh. That is why this page leads with the healthy BMI range and keeps the four formulas as a comparison.
Read sources and limitsWhat is ideal body weight?
An ideal weight calculator estimates a reference weight for your height. This one gives the healthy-weight range, the weights at which your body mass index (BMI) falls between 18.5 and 24.9, and compares it with the four classic ideal body weight (IBW) formulas: Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964).
Ideal body weight began as a pharmacy figure. Ben Devine published his equations in a 1974 case report on gentamicin therapy, as a way to estimate kidney clearance of the drug in obese patients; according to Pai and Paloucek (2000) they were not fitted to any data set and came from his mentor's empirical estimates. Robinson and Miller later refitted the same straight-line form to the 1959 and 1983 Metropolitan Life height-weight tables, also for drug dosing. Hospitals still use IBW, usually Devine, to dose some medicines. None of the four was designed or tested as a health target.
How much should I weigh for my height?
A healthy weight for an adult is a range, not one number. The World Health Organization, the CDC and the 1998 NHLBI clinical guidelines all class BMI 18.5 to 24.9 as a healthy weight, so the range is 18.5 × height² to 24.9 × height², with height in metres.
At 175 cm that is 18.5 × 3.0625 = 56.7 kg to 24.9 × 3.0625 = 76.3 kg; at 5 ft 4 in (162.56 cm) it is 107.8 to 145.1 lb.
That range is the headline here because it is the one tied to health evidence: the BMI classes come from studies of disease risk across whole populations. The four formulas land inside it for most adults between 5 and 6 ft: for a man at 175 cm they give 68.7 to 72.3 kg, a spread of 3.6 kg within a range 19.6 kg wide. A healthy weight calculator that gives you a single figure has picked one point of that range for you.
How do the Devine, Robinson, Miller and Hamwi formulas compare?
All four start from a weight at 5 ft and add a fixed amount for each inch above it. Devine adds 2.3 kg an inch from 50 kg for men and 45.5 kg for women. Robinson starts at 52 and 49 kg and adds 1.9 and 1.7 kg.
Miller starts higher, at 56.2 and 53.1 kg, and adds the least: 1.41 and 1.36 kg. Hamwi, a dietitian's rule rather than a dosing formula, works in pounds: 106 lb plus 6 lb an inch for men, 100 lb plus 5 lb for women.
Because the slopes differ, the formulas agree most closely at about 5 ft 6 in for men and 5 ft 8 in for women, within 1.3 and 1.4 kg of each other, and drift apart from there. At 5 ft 10 in a man gets 70.3 kg from Miller and 75.3 kg from Hamwi. At 4 ft 8 in a woman gets 80.0 lb from Devine and Hamwi, 2.5 lb below the BMI 18.5 weight of 82.5 lb, but 105.1 lb from Miller. Peterson and colleagues (2016) noted that the classic formulas over- and under-estimate at the height extremes, and proposed a single equation tied to BMI instead.
Is ideal weight different for women and by age?
The formulas are: each has a lower starting weight for women, and Robinson, Miller and Hamwi also add less per inch, so an ideal weight calculator for women gives lower figures at the same height. At 160 cm a woman gets 52.1 kg from Hamwi up to 57.2 kg from Miller.
The healthy BMI range is not: 18.5 to 24.9 applies to adult men and women alike, which is why the headline range does not move when you switch sex.
No formula here uses age, and the adult BMI classes are the same at 20 and at 80. The age field only checks that you are an adult and, from 65, adds a note that guidance for older adults differs. Under 20, the CDC reads BMI against age- and sex-specific growth percentiles, which this page does not compute.
Does frame size change ideal weight, and who do the formulas not fit?
Hamwi's rule subtracts 10% for a small frame and adds 10% for a large one, and that is the only frame adjustment this page applies: Devine, Robinson and Miller defined none. For a rough frame reading you can enter your wrist circumference under Advanced.
The page reads it against the MedlinePlus wrist-and-height table, which is a rule of thumb (it has no row for men 5 ft 5 in and under). Elbow-breadth frame tables are not used here.
Below 5 ft the formulas are continued by subtracting their per-inch figure, the extension Robinson et al. reported, and the page flags the result. This calculator gives an estimate from the height you enter, using the published equations named beside the result. It is not a diagnosis or health advice: it cannot see muscle, bone, ethnicity or pregnancy, and it does not apply to children. For many Asian populations the WHO 2004 expert consultation put the first action point at BMI 23, which you can choose under Advanced. A clinician can tell you what suits you.
Ideal Weight questions
What is the ideal weight for a 5'10" man?
128.9 to 173.5 lb is the healthy BMI range at 5 ft 10 in (177.8 cm). The four formulas give 155.0 lb (Miller, 70.3 kg), 156.5 lb (Robinson, 71.0 kg), 160.9 lb (Devine, 73.0 kg) and 166.0 lb (Hamwi), all inside that range. The range is the better guide; the formulas are single points written mainly for drug dosing.
What is the ideal weight for a woman who is 160 cm tall?
47.4 to 63.7 kg, the weights at BMI 18.5 to 24.9 at 160 cm. The formulas fall in the middle: Hamwi 52.1 kg, Devine 52.4 kg, Robinson 54.1 kg and Miller 57.2 kg. Switch the calculator to Female to see them, and to US units for pounds: the range is 104.4 to 140.5 lb.
What is the Devine formula?
50 kg plus 2.3 kg for every inch over 5 feet for men, and 45.5 kg plus 2.3 kg per inch for women. A man at 6 ft (12 in over) gets 50 + 27.6 = 77.6 kg. Devine published it in 1974 to adjust gentamicin doses, and hospitals still use it as the ideal body weight in some dosing calculations.
Which ideal weight formula is the most accurate?
None is accurate in a health sense, because none was tested against health outcomes. Devine came from empirical estimates, Robinson and Miller were fitted to Metropolitan Life insurance tables, and Hamwi is a rule of thumb. The healthy BMI range is the figure linked to disease risk, which is why it is the headline here and the formulas are the comparison.
How do I calculate ideal weight in pounds?
Use Hamwi: 106 lb for the first 5 feet plus 6 lb per inch for men, 100 lb plus 5 lb per inch for women. A woman at 5 ft 4 in gets 100 + 20 = 120 lb; a man at 5 ft 10 in gets 106 + 60 = 166 lb. For the healthy range, multiply 18.5 and 24.9 by height in inches squared and divide by 703.
Is ideal body weight the same as a healthy weight?
No. Ideal body weight (IBW) is one figure from a formula, mostly used to dose medicines. A healthy weight is a range: BMI 18.5 to 24.9 for adults, 56.7 to 76.3 kg at 175 cm. A weight outside the IBW figure but inside the range is still a healthy weight on the WHO and CDC classes.
Does frame size change your ideal weight?
By 10% in Hamwi's rule only: subtract 10% for a small frame and add 10% for a large one. For a man at 175 cm, Hamwi's 72.3 kg becomes 65.1 kg (small) or 79.5 kg (large). Devine, Robinson and Miller have no frame adjustment, and the healthy BMI range does not change with frame.
How do I know my frame size?
Measure your wrist just above the bone and compare it with your height. In the MedlinePlus table a woman 5 ft 2 in to 5 ft 5 in has a medium frame with a 6 to 6.25 in wrist; a man over 5 ft 5 in has a medium frame with a 6.5 to 7.5 in wrist. Enter your wrist under Advanced; it is a rule of thumb.
What is the ideal weight if you are under 5 feet?
Use the healthy BMI range: 82.5 to 111.1 lb at 4 ft 8 in. The formulas start at 5 ft, so below it they subtract their per-inch figure, and at 4 ft 8 in Devine and Hamwi give 80.0 lb, 2.5 lb under the BMI 18.5 weight. The calculator flags any height under 5 ft for that reason.
What is a healthy weight for Asian adults?
52.2 to 64.6 kg at 168 cm on the WHO 2004 Asian cut-off points, against 52.2 to 70.3 kg on the standard ones. The WHO expert consultation found health risk rising at lower BMIs in many Asian populations and set the first action point at 23.0, so the healthy range ends at 22.9. Choose it under Advanced.
Does age change your ideal weight?
Not in any of these formulas, and the adult BMI range of 18.5 to 24.9 is the same from age 20 onward. Body composition does change with age, so the same weight can carry more fat at 70 than at 30. From 65 the calculator adds a note that guidance for older adults differs.
Can I use an ideal weight calculator for children or in pregnancy?
No. All four formulas and the adult BMI range are for adults aged 20 and over who are not pregnant. Children are assessed on CDC BMI-for-age percentile charts, and weight gain in pregnancy is guided by the BMI before pregnancy, which a midwife or doctor can help you read.
Source notes
Method, sources & limitations
Every figure on this page comes from the formula above applied to the values you enter. Nothing is estimated from market data, and no result is a forecast. These are the sources behind the method and any fixed figures it uses:
- Pai MP, Paloucek FP (2000) — The origin of the "ideal" body weight equations, Ann Pharmacother 34:1066–1069 (prints Devine 1974, Robinson 1983 and Miller 1983, Table 1)
- American Diabetes Association, Clinical Diabetes 33(3):123–135 (2015) — Table 2, Calculating desirable body weight (the Hamwi rule and the ±10% frame adjustment)
- Peterson CM, Thomas DM, Blackburn GL, Heymsfield SB (2016) — Universal equation for estimating ideal body weight and body weight at any BMI, Am J Clin Nutr 103:1197–1203
- Centers for Disease Control and Prevention — Adult BMI Categories (healthy weight 18.5 to less than 25)
- NHLBI (1998) — Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults
- WHO Expert Consultation (2004) — Appropriate body-mass index for Asian populations, The Lancet 363:157–163
- MedlinePlus (U.S. National Library of Medicine) — Calculating body frame size (wrist circumference by height; a rule of thumb)
Educational information only. Results are estimates produced from the assumptions you enter, and are not financial, tax, legal or medical advice. Check anything that matters against a qualified professional and the cited sources.