Ideal Weight Calculator
See what the Robinson, Miller, Devine and Hamwi formulas give for your height, beside the BMI 18.5-22.9 band.
Ideal Weight Calculator Tool
Disclaimer: The figures are what four published equations and one BMI band give for a height. They are reference figures, not a weight anyone should aim for, and not a substitute for advice from a doctor or dietitian who knows your health.
How to Use the Ideal Weight Calculator
Enter a height in centimetres or feet and inches
The tool accepts 100 to 250 cm. In imperial, feet is a whole number and inches runs from 0 to 11. Every formula works in inches above 5 ft, so a metric height is converted at exactly 2.54 cm to the inch.
Choose male or female
Each formula has a separate version for men and women. Devine’s two versions share a slope of 2.3 kg per inch, so its male figure is 4.5 kg above its female figure at every height.
Read the four figures and the BMI band side by side
From 5 ft (152.4 cm) up, the table shows what Robinson, Miller, Devine and Hamwi each give, the gap between the lowest and highest, and the weight range for BMI 18.5–22.9 at that height. Below 5 ft it shows the BMI band only, because the formulas are not defined there.
Treat every number as a reference, not a target
None of the four was published as a personal weight goal: three come from drug-dosing work and one from a diabetes diet text. The BMI band is a population risk category. A doctor or dietitian is the person to set a goal with.
Where the four ideal-body-weight equations came from
From life-insurance tables to drug dosing
Peterson and colleagues (2016) write that ideal or desirable weight “was originally defined as the weight associated with the greatest life expectancy at each height”, a reading taken from life-insurance height-weight tables. Pai and Paloucek (2000) describe how the tables’ weights were found to correlate with mortality, which is how the words “desirable” and “ideal” came to be attached to them.
The equations on this page came later, and mostly for medicines. Devine’s traces to a 1974 case study on gentamicin therapy in Drug Intelligence & Clinical Pharmacy. Robinson’s 1983 paper is titled “Determination of ideal body weight for drug dosage calculations”, and Peterson says Robinson and Miller were “motivated by applications to drug dosing”, working from the 1959 and 1983 Metropolitan Life tables respectively. Hamwi’s rule is the exception: it comes from a 1964 American Diabetes Association text on diet.
“A formula written to dose a drug answers a narrower question than how much a person should weigh.”
Four straight lines that cross near 168 cm
Each equation is a weight at 5 ft plus a fixed amount for every inch above it. The tool uses the constants printed in Table 3 of Peterson 2016: Robinson 52 kg + 1.9 kg per inch for men and 49 + 1.7 for women; Miller 56.2 + 1.41 and 53.1 + 1.36; Devine 50 + 2.3 and 45.5 + 2.3; and Hamwi in pounds, 106 lb + 6 lb per inch and 100 + 5, converted exactly to kilograms. Robinson’s own abstract gives 51.65 + 1.85 and 48.67 + 1.65; the rounded form Peterson prints is the one most calculators use.
Because the bases and slopes differ, the lines cross. For a man of 170 cm, Robinson gives 65.2 kg, and for a woman of the same height 60.8 kg. For men the four come closest near 168 cm, about 1.2 kg apart; Miller gives the highest figure below that height and Hamwi above it. At 195 cm the male figures run from 79.8 kg (Miller) to 93.7 kg (Hamwi), 13.9 kg apart. For women they come closest near 173 cm, about 1.4 kg apart, with Miller highest below that height and Devine above it.
Below 5 feet the equations have no answer
Every one of the four is written as (height − 60 inches). Peterson states the limit of 60 inches and over for Devine and Hamwi, and Sawyer and colleagues (1983), studying creatinine-clearance estimates, found the use of ideal or lean body weight “not appropriate in patients less than 60 inches tall”. Extended below 5 ft the straight lines keep falling: Devine would give a 140 cm woman 34.3 kg, a BMI of 17.5. So below 152.4 cm this tool shows no formula figures, only the BMI band.
The BMI band beside them
The last row is not a formula. It is the weight range for a BMI of 18.5 up to (but not including) 23.0 at the height entered. Singapore’s National Population Health Survey 2022 classifies weight by WHO’s international 18.5–24.9 “normal weight” range, and separately reports an Asian BMI risk classification from the 2004 WHO expert consultation: “Low risk” 18.5–22.9, “Moderate risk” 23.0–27.4 and “High risk” 27.5 and above. The same survey uses waist cut-offs of over 90 cm for men and over 80 cm for women.
Peterson’s Table 4 puts the older equations’ best-fit BMIs between 21.0 and 23.4, so for most adult heights the four figures sit near or inside that band rather than far from it. Both the formulas and the band use height and sex alone. Neither knows anything about muscle, frame, age or health.
A gentamicin case study, a diet text and two pharmacy papers
Robinson’s 1983 abstract gives men 51.65 kg + 1.85 kg per inch over 5 ft. The 52 + 1.9 most calculators use, this one included, is the rounding Peterson 2016 prints.
Crossref lists the 1974 source of the Devine equation as “Case Number 25 Gentamicin Therapy”, a clinical-pharmacy case study by McCarron and Devine.
Hamwi’s rule is published in pounds: 106 lb at 5 ft plus 6 lb per inch for men, 100 lb plus 5 lb for women (Peterson 2016, Table 3).
Peterson and colleagues write that ideal or desirable weight first meant the weight with the greatest life expectancy at each height, in insurance height-weight tables.
For men the four equations come closest near 168 cm, about 1.2 kg apart. At 195 cm they are 13.9 kg apart.
For women, Miller gives the highest figure up to about 173 cm and Devine above it. For men, Hamwi is highest from about 168 cm.
In a 1983 study of creatinine-clearance estimates, Sawyer and colleagues found ideal body weight “not appropriate in patients less than 60 inches tall”.
Singapore’s 2022 National Population Health Survey labels BMI 18.5–22.9 “Low risk” and 23.0–27.4 “Moderate risk”, citing WHO 2004.
The 2004 WHO consultation found the cut-off for observed risk varies from 22 to 25 across Asian populations, and kept WHO’s cut-offs as the international classification.
Peterson’s own equation gives the weight for any chosen BMI: 2.2 × BMI + 3.5 × BMI × (height − 1.5 m), in kilograms.
Frequently Asked Questions
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None of them was built to tell a person what to weigh, so “accurate” depends on the yardstick. Shah, Sucher and Hollenbeck (2006) compared them against BMI and wrote that “Robinson’s formula appears to be the best equation for calculating desirable/healthy weights in men; however, no formula predicted close to a BMI of 22 kg/m2 for women.” Peterson 2016 found the older equations align with BMIs between 21.0 and 23.4, depending on the formula and sex.
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Each has its own weight at 5 ft and its own amount per inch, so the four lines cross: for men they are about 1.2 kg apart near 168 cm and 13.9 kg apart at 195 cm. Pai and Paloucek (2000) concluded that “the similarity between the IBW equations was a result of the general agreement among the various height-weight tables from which they were derived. Therefore, any one of these equations may be used to estimate IBW.” That conclusion is about estimating ideal body weight in clinical use, not about choosing a personal weight.
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All four are written as a weight at 5 ft plus an amount per inch above it. Peterson 2016 gives the Devine and Hamwi equations for heights of 60 inches and over, and Sawyer 1983, studying creatinine-clearance estimates, found ideal body weight “not appropriate in patients less than 60 inches tall”. Some calculators extend the lines downward anyway; this one shows only the BMI band below 152.4 cm rather than invent a figure.
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The 2004 WHO expert consultation found that “the cut-off point for observed risk varies from 22 kg/m2 to 25 kg/m2 in different Asian populations”. It kept WHO’s cut-offs as the international classification and named 23.0, 27.5, 32.5 and 37.5 as potential public-health action points. Singapore’s 2022 health survey reports both: WHO’s 18.5–24.9 “normal weight”, and an Asian risk classification of 18.5–22.9 low risk, 23.0–27.4 moderate risk and 27.5 and above high risk.
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Drug dosing. It traces to a 1974 case study on gentamicin therapy in Drug Intelligence & Clinical Pharmacy, credited to Devine. Pai and Paloucek (2000) write that “the pharmacokinetics of certain drugs were found to correlate with IBW and resulted in the use of IBW equations published by Devine.” The tool shows it as a reference figure; it is not dosing software.
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No. The four formulas and the BMI band read only height and sex. Two people of the same height and sex get identical figures whatever their muscle, bone, age or health, which is one reason none of the figures should be read as a personal goal.
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No. The tool reports what published equations and a population BMI band give for a height; it does not set targets. Whether a change in weight makes sense for you is a question for a doctor or dietitian who can look at your health as a whole.
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Method & sources
How it computes
Four ideal-body-weight equations, each a weight at 5 ft plus a fixed amount per inch, with the constants of Peterson 2016 Table 3: Robinson 1983 52+1.9 / 49+1.7 kg, Miller 1983 56.2+1.41 / 53.1+1.36 kg, Devine 1974 50+2.3 / 45.5+2.3 kg, Hamwi 1964 106+6 / 100+5 lb. Shown only from 152.4 cm, as reference figures beside the BMI 18.5-22.9 band (WHO 2004 Asian cut-offs); no target and no verdict.
What this tool implements
- Constants as Peterson 2016 Table 3 prints them. Robinson's own abstract gives 51.65 + 1.85 kg/in (men) and 48.67 + 1.65 (women); the rounded 52 + 1.9 and 49 + 1.7 differ by up to about 1.2 kg over 152.4-195 cm. Hamwi is converted exactly from pounds (1 lb = 0.45359237 kg). Devine's and Miller's constants rest on Peterson alone: the 1974 case study and the 1983 letter were not opened.
- Domain: every equation is written as (height - 60 in). Peterson states the >= 60 in limit for Devine and Hamwi, and Sawyer 1983 found IBW "not appropriate in patients less than 60 inches tall". Below 152.4 cm no formula figure is shown, only the BMI band; heights outside 100-250 cm are refused.
- Origins, as the sources state them: Devine's equation traces to a 1974 gentamicin-therapy case study (Crossref: McCarron MM, Devine BJ); Robinson 1983 is titled "for drug dosage calculations" and used the 1959 Metropolitan Life tables, Miller 1983 the 1983 tables (Peterson 2016); Hamwi comes from a 1964 American Diabetes Association diet text. "Ideal" first meant the weight with the greatest life expectancy in insurance tables (Peterson 2016; Pai & Paloucek 2000).
- BMI band [18.5, 23.0), labelled 18.5-22.9, read from the same kernel table as /bmi-calculator/: the Asian risk classification of WHO 2004 as Singapore's NPHS 2022 Table 13.2 reports it ("Low risk" 18.5-22.9, "Moderate risk" 23.0-27.4, "High risk" >= 27.5). Shown as a population risk band, never as a target.
- Corrected 2026-10-18: formulas extended below 5 ft (to negative weights at 50 cm); a mean-of-four +/-5% "Ideal Weight Range" whose top sat above BMI 23 for men from 149 cm, with a below/within/above verdict on the reader's weight; Hamwi as 48 + 2.7 / 45.4 + 2.3 kg; Robinson's 170 cm example (66.5 / 62.3 kg, now 65.2 / 60.8); "Devine gives the highest at tall heights" (Hamwi does, for men); "differ by up to 10%"; "5-10% above the Asian range"; "five formulas"; "primary target" and "aim for the lower half"; Robinson's table year (1959, not 1983); WPRO 2000 credited for 18.5-22.9; unsourced "40% of healthy-BMI adults", "US military", "18% denser" and "15% bone" claims; inches never validated; tool id RT-HLT-006 on the widget.
Sources
- Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Ann Pharmacother 2000;34(9):1066-9. PMID 10981254
- 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):1016-9. PMID 6869387
- Determining ideal body weight (and mass) [letter]. Am J Hosp Pharm 1983;40(10):1622, 1625. PMID 6638023 — the 1983 letter behind the equation known as Miller's; PubMed lists no author line.
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet 2004;363(9403):157-63. PMID 14726171
- 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):1197-203 (Table 3: the constants used here). https://pmc.ncbi.nlm.nih.gov/articles/PMC4841935/
- Sawyer WT, Canaday BR, Poe TE, Webb CE, Gal P, Joyner PU, Berry JI. Variables affecting creatinine clearance prediction. Am J Hosp Pharm 1983;40(12):2175-80. PMID 6660232
- McCarron MM, Devine BJ. Clinical pharmacy: case studies. Case number 25: gentamicin therapy. Drug Intell Clin Pharm 1974;8(11):650-5. https://doi.org/10.1177/106002807400801104
- 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):312-9. PMID 16772549
What can make this go out of date
- None at runtime — the equations and the BMI cut-offs are fixed publications.
Abridged — the full review record for this tool runs longer than the list above.
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