The Quick Answer
Ideal body weight (IBW) is a clinical estimate of how much a person should weigh based on their height and sex, originally developed for drug dosing calculations rather than fitness goals.
The four most widely used IBW formulas are Devine (1974), Hamwi (1964), Robinson (1983), and Miller (1983). For a 5'10" male, they produce a range of approximately 66-75 kg (146-165 lbs). For a 5'5" female, the range is roughly 55-62 kg (121-136 lbs).
All four formulas share the same basic structure: a baseline weight for a height of 5 feet (60 inches), plus an increment for each additional inch of height.
The Four Formulas
Each formula calculates IBW in kilograms. Height is measured in inches, and the variable portion applies to each inch above 60 inches (5 feet).
Devine (1974)
- Men: IBW = 50 + 2.3 x (height in inches - 60)
- Women: IBW = 45.5 + 2.3 x (height in inches - 60)
Published by B.J. Devine in 1974, this is the most commonly cited formula in clinical practice. It was originally developed for calculating gentamicin dosages and was not based on large-scale population data. Despite this, it became the default IBW formula in pharmacy and medicine.
Hamwi (1964)
- Men: IBW = 48 + 2.7 x (height in inches - 60)
- Women: IBW = 45.5 + 2.2 x (height in inches - 60)
The Hamwi method predates Devine and was developed by G.J. Hamwi as a quick clinical estimation tool. It uses a higher per-inch increment for men (2.7 kg vs. 2.3 kg), which means it diverges more from Devine at taller heights.
Robinson (1983)
- Men: IBW = 52 + 1.9 x (height in inches - 60)
- Women: IBW = 49 + 1.7 x (height in inches - 60)
Robinson and colleagues published this formula as a refinement based on mortality statistics from the Metropolitan Life Insurance tables. It uses a lower per-inch factor, which produces more conservative estimates for taller individuals.
Miller (1983)
- Men: IBW = 56.2 + 1.41 x (height in inches - 60)
- Women: IBW = 53.1 + 1.36 x (height in inches - 60)
The Miller formula has the highest baseline weight but the lowest per-inch increment. It was developed as another alternative based on actuarial data and tends to produce the least variation across heights.
Worked Example: Male, 5'10" (70 inches)
Each inch above 60 inches = 70 - 60 = 10 inches.
| Formula | Calculation | Result (kg) | Result (lbs) |
|---|---|---|---|
| Devine | 50 + 2.3 x 10 | 73.0 | 160.9 |
| Hamwi | 48 + 2.7 x 10 | 75.0 | 165.3 |
| Robinson | 52 + 1.9 x 10 | 71.0 | 156.5 |
| Miller | 56.2 + 1.41 x 10 | 70.3 | 155.0 |
Range: 70.3 - 75.0 kg (155 - 165 lbs)
The four formulas agree within about 5 kg (11 lbs) for a 5'10" male. Devine and Hamwi produce higher results; Robinson and Miller are more conservative.
Worked Example: Female, 5'5" (65 inches)
Each inch above 60 inches = 65 - 60 = 5 inches.
| Formula | Calculation | Result (kg) | Result (lbs) |
|---|---|---|---|
| Devine | 45.5 + 2.3 x 5 | 57.0 | 125.7 |
| Hamwi | 45.5 + 2.2 x 5 | 56.5 | 124.6 |
| Robinson | 49 + 1.7 x 5 | 57.5 | 126.8 |
| Miller | 53.1 + 1.36 x 5 | 59.9 | 132.0 |
Range: 56.5 - 59.9 kg (125 - 132 lbs)
For women closer to 5 feet, the formulas converge more tightly. The Miller formula produces the highest estimate here because of its higher baseline (53.1 kg vs. 45.5 kg).
Full Comparison Table
| Formula | Year | Male 5'10" (kg) | Female 5'5" (kg) | Originally designed for |
|---|---|---|---|---|
| Devine | 1974 | 73.0 | 57.0 | Drug dosing (gentamicin) |
| Hamwi | 1964 | 75.0 | 56.5 | Quick clinical estimation |
| Robinson | 1983 | 71.0 | 57.5 | Refinement from mortality data |
| Miller | 1983 | 70.3 | 59.9 | Refinement from actuarial data |
Adjusted Body Weight for Clinical Use
When a patient's actual weight significantly exceeds their IBW, clinicians often use adjusted body weight (ABW) for dosing calculations:
ABW = IBW + 0.4 x (actual weight - IBW)
Worked example: A male patient is 5'10" (Devine IBW = 73.0 kg) but weighs 110 kg.
- ABW = 73.0 + 0.4 x (110 - 73.0)
- ABW = 73.0 + 0.4 x 37.0
- ABW = 73.0 + 14.8
- ABW = 87.8 kg
The 0.4 factor accounts for the fact that excess body mass above IBW is not purely fat -- it includes some lean tissue and increased blood volume. Different medications may use different adjustment factors; this is a general guideline. The ABW concept is reviewed in detail by Pai and Paloucek (2000) in the Annals of Pharmacotherapy.
Limitations
These formulas have several well-documented shortcomings:
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No muscle mass distinction. A 5'10" male bodybuilder at 95 kg with 10% body fat is far healthier than the formulas suggest. IBW treats all weight equally.
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No frame size adjustment. People have different skeletal frames (small, medium, large). A large-framed person will naturally weigh more at the same height without being overweight.
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No ethnicity consideration. All four formulas were developed from predominantly Western populations. Body composition norms vary across ethnic groups.
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No age factor. Body composition changes with age. These formulas produce the same result for a 25-year-old and a 70-year-old at the same height.
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Not designed as health targets. The Devine formula -- the most commonly used -- was created for pharmaceutical dosing. Using it as a personal weight goal misapplies its intended purpose.
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Height range. The formulas are designed for adults 60 inches (152.4 cm) and taller. They are not validated for shorter individuals.
For a more complete picture, IBW should be considered alongside BMI, body fat percentage, waist circumference, and clinical assessment.
Frequently Asked Questions
Which ideal weight formula is most accurate?
No single formula is universally most accurate. Devine is the most widely used clinically, but Robinson and Miller were developed using broader data. Calculating all four and examining the range gives the most balanced picture.
Why do the four IBW formulas give different results?
Each was developed by different researchers, from different populations, with different methods. The per-inch coefficient and baseline weight differ based on the data and assumptions each researcher used.
Is ideal body weight the same as healthy weight?
No. IBW is a clinical estimate using only height and sex. Healthy weight depends on body composition, fitness, age, genetics, and medical history. A person can be medically healthy at a weight outside their IBW range.
Do these formulas work for athletes?
Generally not. Athletes with significant muscle mass will exceed their calculated IBW. Body fat percentage and lean mass measurements are more appropriate for athletic populations.
Why was ideal body weight originally developed?
The Devine (1974) formula was published for calculating gentamicin drug dosages. Many medications are dosed relative to lean body mass, and IBW served as a practical estimate. It was adopted for broader use despite never being validated as a health or fitness metric.
What is adjusted body weight and when is it used?
ABW = IBW + 0.4 x (actual weight - IBW). It is used when a patient weighs substantially more than their IBW, typically for medication dosing in obese patients. The factor 0.4 reflects that excess weight includes some metabolically active tissue.
Do ideal body weight formulas apply to all ethnicities?
These formulas were developed from primarily Caucasian American populations. Bone density, frame size, and body composition vary across ethnicities, which limits their cross-cultural applicability.
Can I use these formulas if I am under 5 feet tall?
The formulas are designed for heights of 60 inches (5 feet) and above. Below this height, they return only the baseline value, which has not been validated for shorter stature.
How do I convert ideal body weight from kilograms to pounds?
Multiply kilograms by 2.205. For example, 70 kg x 2.205 = 154.3 lbs.
Should I aim to weigh exactly my ideal body weight?
No. The four formulas produce a range spanning 10-20 lbs for most people. IBW is a rough reference point, not a precise target. Overall health, body composition, and how you feel matter more than matching a single number.
Calculate Your Ideal Weight
Use the ideal weight calculator to calculate your IBW using all four formulas instantly. Enter your height and sex, and see results from Devine, Hamwi, Robinson, and Miller side by side.
For related metrics, try the BMI calculator or the body fat calculator.
This content is for educational purposes only and does not constitute medical advice. Consult a healthcare provider for guidance on weight management and medication dosing.