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Formula
IBW = base weight at 5 ft + increment × (height in inches − 60); healthy BMI range = 18.5 × h² to 24.9 × h²
- IBW
- ideal body weight from one of the four formulas
- base weight
- Devine 50 kg (men) or 45.5 kg (women); Robinson 52 or 49 kg; Miller 56.2 or 53.1 kg; Hamwi 106 or 100 lb
- increment
- added per inch over 5 ft: Devine 2.3 kg; Robinson 1.9 or 1.7 kg; Miller 1.41 or 1.36 kg; Hamwi 6 or 5 lb
- h
- height in meters, for the BMI range in kilograms
What the ideal weight calculator shows
“Ideal weight” has no single definition, so this ideal weight calculator shows the main answers next to each other:
- Four ideal body weight (IBW) formulas: Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964), each for your sex and height.
- The range they span, shown as the main result, from the lowest to the highest of the four.
- The healthy BMI weight range, every weight that gives a BMI from 18.5 to 24.9 at your height.
- The working for each formula, so you can check the numbers.
Enter your sex and height in inches or centimeters, and choose whether to see the weights in pounds or kilograms.
How the ideal body weight formulas work
All four formulas share the same shape. They start from a base weight for someone exactly 5 ft (60 in) tall and add a fixed amount for every inch above that. They differ only in the two numbers.
| 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) | 106 lb + 6 lb per inch | 100 lb + 5 lb per inch |
Hamwi was published in pounds and the others in kilograms. The calculator applies each one in its original unit before converting, so results match the published versions exactly.
The healthy BMI range comes from the BMI formula run in reverse: weight = BMI × height². With height in meters, 18.5 × h² gives the lower end in kilograms and 24.9 × h² the upper end.
How to calculate ideal weight for height by hand
Take a woman 5 ft 6 in tall, which is 66 in, or 6 in over 5 ft.
- Devine: 45.5 + 2.3 × 6 = 59.3 kg, about 130.7 lb.
- Robinson: 49 + 1.7 × 6 = 59.2 kg, about 130.5 lb.
- Miller: 53.1 + 1.36 × 6 = 61.26 kg, about 135.1 lb.
- Hamwi: 100 + 5 × 6 = 130 lb.
- Healthy BMI range: 66 in is 1.6764 m, and 1.6764² ≈ 2.8103. So 18.5 × 2.8103 ≈ 52.0 kg (114.6 lb) and 24.9 × 2.8103 ≈ 70.0 kg (154.3 lb).
The four formulas cluster between 130 and 135 lb, inside a healthy BMI range of about 115 to 154 lb.
Ideal weight chart by height
Values were calculated with the same formulas the calculator uses and rounded to the nearest pound.
Men
| Height | Devine | Robinson | Miller | Hamwi | Healthy BMI range |
|---|---|---|---|---|---|
| 5 ft 4 in | 131 lb | 131 lb | 136 lb | 130 lb | 108–145 lb |
| 5 ft 6 in | 141 lb | 140 lb | 143 lb | 142 lb | 115–154 lb |
| 5 ft 8 in | 151 lb | 148 lb | 149 lb | 154 lb | 122–164 lb |
| 5 ft 10 in | 161 lb | 157 lb | 155 lb | 166 lb | 129–174 lb |
| 6 ft 0 in | 171 lb | 165 lb | 161 lb | 178 lb | 136–184 lb |
| 6 ft 2 in | 181 lb | 173 lb | 167 lb | 190 lb | 144–194 lb |
| 6 ft 4 in | 191 lb | 182 lb | 174 lb | 202 lb | 152–205 lb |
Women
| Height | Devine | Robinson | Miller | Hamwi | Healthy BMI range |
|---|---|---|---|---|---|
| 5 ft 0 in | 100 lb | 108 lb | 117 lb | 100 lb | 95–127 lb |
| 5 ft 2 in | 110 lb | 116 lb | 123 lb | 110 lb | 101–136 lb |
| 5 ft 4 in | 121 lb | 123 lb | 129 lb | 120 lb | 108–145 lb |
| 5 ft 6 in | 131 lb | 131 lb | 135 lb | 130 lb | 115–154 lb |
| 5 ft 8 in | 141 lb | 138 lb | 141 lb | 140 lb | 122–164 lb |
| 5 ft 10 in | 151 lb | 146 lb | 147 lb | 150 lb | 129–174 lb |
| 6 ft 0 in | 161 lb | 153 lb | 153 lb | 160 lb | 136–184 lb |
The formulas agree closely at average heights and spread apart for tall men: at 6 ft 4 in, Miller and Hamwi differ by 28 lb. The BMI range is the same for both sexes because BMI does not depend on sex.
Ideal weight vs. a healthy weight range
The IBW formulas began as tools for dosing medicines and were never meant as personal goals. Peterson and colleagues showed in 2016 that each one implies a different BMI: about 22.8 for Devine’s male formula, for example, and 21.0 for Robinson’s female formula. In practice, they all land near the middle of the healthy BMI range.
The BMI range is wider and usually more useful. For most adults, any weight inside it is associated with lower health risk. Neither measure accounts for muscle, though, so a strong, muscular person may sit above both and still be lean. The body fat calculator estimates how much of your weight is fat, and the BMI calculator shows where your current weight falls.
Ways people use an ideal weight calculator
- Setting a realistic goal. Aim for somewhere in the healthy BMI range rather than one exact number. If you need a target, the formula average is a reasonable middle point.
- Planning calories. Once you have a goal weight, the calorie calculator estimates how much to eat to move toward it gradually.
- Understanding clinical paperwork. Hospital notes and drug labels often mention “IBW”. It almost always means the Devine formula.
Common mistakes
- Treating the ideal weight calculator result as a target you must hit. Weights a few pounds either side of every formula can be perfectly healthy.
- Entering height in shoes. An extra inch adds 5 to 6 lb to the Devine and Hamwi results.
- Using the formulas for children. They were built for adults; children need age- and sex-specific growth charts.
- Ignoring body composition. Athletes often exceed their ideal weight because of muscle, not fat.
If your current weight is well outside the healthy BMI range, or you are unsure what goal is right for you, a doctor or registered dietitian can help you set one that suits your health.
Worked examples
A man 5 ft 11 in tall
Male, 71 inches (5 ft 11 in), results in pounds.
Inputs: Sex = Male; Height = 71; Height unit = Inches; Show weights in = Pounds (lb)
Height: 71 in, which is 11 in over 5 ft Devine: 50 kg + 2.3 kg × 11 = 75.3 kg = 166.0 lb Robinson: 52 kg + 1.9 kg × 11 = 72.9 kg = 160.7 lb Miller: 56.2 kg + 1.41 kg × 11 = 71.7 kg = 158.1 lb Hamwi: 106 lb + 6 lb × 11 = 172.0 lb Healthy BMI range: 18.5 × 1.8034² = 60.2 kg to 24.9 × 1.8034² = 81.0 kg
Answer: Ideal weight for a male 71 in tall: 158.1–172.0 lb across the Devine, Robinson, Miller and Hamwi formulas; healthy BMI range 132.6–178.5 lb. An estimate, not medical advice.
A woman 160 cm tall, in kilograms
Female, 160 cm (about 5 ft 3 in), results in kilograms.
Inputs: Sex = Female; Height = 160; Height unit = Centimeters; Show weights in = Kilograms (kg)
Height: 62.99 in, which is 2.99 in over 5 ft Devine: 45.5 kg + 2.3 kg × 2.99 = 52.4 kg Robinson: 49 kg + 1.7 kg × 2.99 = 54.1 kg Miller: 53.1 kg + 1.36 kg × 2.99 = 57.2 kg Hamwi: 100 lb + 5 lb × 2.99 = 115.0 lb = 52.1 kg Healthy BMI range: 18.5 × 1.6² = 47.4 kg to 24.9 × 1.6² = 63.7 kg
Answer: Ideal weight for a female 62.99 in tall: 52.1–57.2 kg across the Devine, Robinson, Miller and Hamwi formulas; healthy BMI range 47.4–63.7 kg. An estimate, not medical advice.
A short woman under 5 ft (edge case)
Female, 58 inches (4 ft 10 in). Below 5 ft the formulas subtract weight, so the BMI range matters more.
Inputs: Sex = Female; Height = 58; Height unit = Inches; Show weights in = Pounds (lb)
Height: 58 in, which is 2 in under 5 ft Devine: 45.5 kg + 2.3 kg × −2 = 40.9 kg = 90.2 lb Robinson: 49 kg + 1.7 kg × −2 = 45.6 kg = 100.5 lb Miller: 53.1 kg + 1.36 kg × −2 = 50.4 kg = 111.1 lb Hamwi: 100 lb + 5 lb × −2 = 90.0 lb Healthy BMI range: 18.5 × 1.4732² = 40.2 kg to 24.9 × 1.4732² = 54.0 kg
Answer: Ideal weight for a female 58 in tall: 90.0–111.1 lb across the Devine, Robinson, Miller and Hamwi formulas; healthy BMI range 88.5–119.1 lb. An estimate, not medical advice.
Assumptions and limitations
- This is an estimate, not medical advice. Ideal body weight formulas give a single reference number for a height; they do not account for frame size, muscle mass, age or health conditions.
- Devine, Robinson and Miller are applied in kilograms and Hamwi in pounds, exactly as published, then converted to the unit you choose (1 lb = 0.45359237 kg).
- The formulas were built for adults 5 ft (152.4 cm) and taller. Heights from 4 ft 6 in to 7 ft 6 in are accepted, but below 5 ft the formulas subtract weight per inch and a note recommends relying on the BMI range and a doctor's advice.
- The healthy BMI range uses BMI 18.5 to 24.9, the adult healthy-weight category used by the CDC and NIH. It applies to adults 20 and over, not to children, teens or pregnant women.
- Results are rounded to 0.1 lb or 0.1 kg.
Frequently asked questions
Which ideal weight formula is the most accurate for men and women?
None is accurate for an individual, because they were built from population height-weight tables. In a 2016 comparison with BMI, the Robinson formula tracked a constant BMI most closely. Devine is the most widely used, mainly for drug dosing. The spread between all four is a better guide than any single number.
Why do the four formulas give different answers?
Each was fitted to different data. Hamwi (1964) was a quick clinical rule of thumb, Devine (1974) was written for gentamicin dosing, and Robinson and Miller (1983) were refits to Metropolitan Life height-weight tables. They agree closely around 5 ft 6 in and spread apart for very tall people.
What is the ideal weight for a woman who is 5 ft 4 in?
The four formulas give about 120 to 129 lb for a woman 64 in tall, and the healthy BMI range is about 108 to 145 lb. Any weight in the BMI range is considered a healthy weight for an adult of that height.
Is ideal weight the same as a healthy weight?
Not exactly. Ideal body weight is one reference number per height, originally used to dose medicines. A healthy weight is a range, usually BMI 18.5 to 24.9. A muscular person can be above their ideal weight and still be healthy, so body composition and waist size matter too.
Do these formulas work for people under 5 ft?
They were not designed for it. Below 5 ft they subtract a fixed amount per inch, which drifts toward implausibly low weights. Use the healthy BMI range instead and check with a doctor or dietitian.
How is ideal body weight used in medicine?
Doctors and pharmacists use it to dose some drugs that do not dissolve well in fat, such as certain antibiotics, and to set ventilator volumes in intensive care. The Devine formula is the usual choice for this.
Sources
- Universal equation for estimating ideal body weight and body weight at any BMI — American Journal of Clinical Nutrition (Peterson et al., 2016), via PubMed Central. Checked October 10, 2026.
- The origin of the "ideal" body weight equations — Annals of Pharmacotherapy (Pai & Paloucek, 2000), via PubMed. Checked October 10, 2026.
- Determination of ideal body weight for drug dosage calculations — American Journal of Hospital Pharmacy (Robinson et al., 1983), via PubMed. Checked October 10, 2026.
- Adult BMI Categories — Centers for Disease Control and Prevention. Checked October 10, 2026.
- Calculate Your BMI — National Heart, Lung, and Blood Institute (NIH). Checked October 10, 2026.