What this calculator returns
IBW means ideal body weight. This page returns Devine IBW as the primary adult clinical reference weight and can optionally show Robinson and Miller comparison estimates.
Clinical Ideal Body Weight (IBW) Calculator
Clinical body-weight calculation
What is the patient’s Devine IBW?
Select the Devine equation specified by the clinical reference, then enter the adult patient’s height.
Sex used by the Devine equation
The Devine equations use different base weights. Use the equation specified by the relevant clinical reference or protocol.
Height entry
cm
Enter 152.4 cm or taller without the unit, such as 175.
Height limit for this calculator
For adults under 5 feet (152.4 cm), MedMaths does not extrapolate the standard Devine equation. Follow the method specified by the relevant medicine reference or local protocol.
Selected equation explained
How the Male Devine equation works
Select male or female above to update this equation. The calculator remains first so the clinical reference weight can be obtained without reading the longer explanation.
Male Devine ideal body weight formula
In simple words
Convert height to inches, subtract 60 inches (5 feet), multiply the inches above 5 feet by 2.3 kg, then add 50 kg.
- IBW
- = ideal body weight returned by the Devine equation, in kilograms
- height
- = adult height in inches; centimetres are divided by 2.54 first
- 60
- = 60 inches, which equals 5 feet
- 2.3
- = kilograms added for each inch above 5 feet
Why the male and female Devine results differ
Both equations add 2.3 kg for each inch above 5 feet. The male equation starts from 50 kg and the female equation starts from 45.5 kg, so the same height produces results that differ by 4.5 kg.
Use the IBW method and weight measure named by the protocol
Devine is the primary result. Optional Robinson and Miller values are separate estimates, not substitutes for a named protocol method. This calculator does not decide whether a medicine requires actual, ideal, adjusted, lean, or another body-weight measure.
Verify the height, equation sex term, named IBW method, required body-weight measure, and final calculation independently.
IBW formula (Devine). Men: 50 kg + 2.3 kg for every inch over 5 feet (60 in, 152.4 cm). Women: 45.5 kg + 2.3 kg for every inch over 5 feet. Example: a woman 165 cm tall is about 65 in, which is 5 in over 5 feet, so her IBW is about 56.9 kg. Use the formula your protocol names, and remember IBW is a formula result, not a measured weight.
Simple answer
How to calculate ideal body weight (IBW)
MedMaths uses the Devine equation as its default adult clinical IBW result. For adults at or above 5 feet (152.4 cm), Devine uses a base weight at 5 feet and adds 2.3 kg for each inch above 5 feet.
Male
Female
Example: A 175 cm male adult is 68.90 inches tall, or 8.90 inches above 5 feet. 50 + (2.3 × 8.90) = about 70.5 kg.
Devine IBW is a clinical reference weight, not a healthy target weight. The calculator can optionally show Robinson and Miller estimates for comparison, but the methods should not be averaged or substituted for a protocol that names one equation.
What it does not return
It does not calculate a healthy target weight, adjusted body weight, measured actual weight, ventilation predicted body weight, or a “best” average across IBW formulas.
Clinical interpretation
A result such as 70.5 kg means the Devine equation returned 70.5 kg for the entered adult height. Optional Robinson and Miller values are separate estimates; use the method named by the medication reference or protocol. If that source explicitly requires adjusted body weight (AdjBW) rather than IBW, continue to the Adjusted Body Weight Calculator.
Clinical use and safety
When to use this calculator — and its limits
The arithmetic can be correct while the clinical decision is still wrong. These boundaries show what the calculator can and cannot establish.
When to use
- Use when an adult medication reference, clinical equation, or local protocol requires an IBW estimate; Devine remains the default MedMaths method.
- Enter adult height and select the male or female term used by the Devine equation named in the source you are following.
- Treat the result as a historical clinical reference weight, not as the patient’s measured weight or a target weight.
Key limitations
- The Devine equations are historical height-based estimates first published in a 1974 gentamicin case study; they were not developed as a modern outcome-based definition of an individual’s healthy or optimal weight.
- IBW is not the same as lean body weight, fat-free mass, predicted body weight for ventilation, or adjusted body weight.
- Other published IBW equations use different constants and can return different values for the same height; optional Robinson and Miller comparisons are not interchangeable with Devine.
- The original Devine equation is expressed for inches above 5 feet. MedMaths deliberately does not extrapolate it below 152.4 cm (5 feet).
- This page is an adult Devine calculator; paediatric ideal-weight methods are different and should not be substituted with this equation.
What MedMaths does not decide
- Whether a medicine should use actual, ideal, adjusted, lean, or another dosing weight, or which IBW equation a protocol intends when it names one specifically.
- A patient’s healthy target weight, nutrition goal, or body-composition status.
- Ventilation predicted body weight or any ventilator setting.
- A medication dose, maximum dose, dose reduction, or dosing frequency.
Evidence and method checks
- The Origin of the ‘Ideal’ Body Weight Equations — Annals of Pharmacotherapy / SAGE
- Clinical Pharmacy: Case Studies: Case Number 25 Gentamicin Therapy — Drug Intelligence & Clinical Pharmacy / SAGE
- eviQ body-size formula reference — eviQ / Cancer Institute NSW
- Universal equation for estimating ideal body weight and body weight at any BMI — American Journal of Clinical Nutrition / PubMed
Formula logic and known-value examples are checked as part of the MedMaths review process.
See how MedMaths checks calculator methods →Formula, examples and learning guide
Review the Devine formula, optional comparison formulas, worked examples, body-weight distinctions and common questions.
Formula, examples and learning guide
Review the Devine formula, optional comparison formulas, worked examples, body-weight distinctions and common questions.
How is ideal body weight calculated?
Height in centimetres is divided by 2.54 to convert it to inches. For adults at least 5 feet tall, the equation subtracts 60 inches, multiplies the inches above 5 feet by 2.3 kg, and adds the selected base weight.
Male Devine ideal body weight formula
In simple words
Convert height to inches, subtract 60 inches (5 feet), multiply the inches above 5 feet by 2.3 kg, then add 50 kg.
- IBW
- = ideal body weight in kilograms
- height
- = height in inches; divide centimetres by 2.54 first
- 60
- = 60 inches, equal to 5 feet
Female Devine ideal body weight formula
In simple words
Convert height to inches, subtract 60 inches (5 feet), multiply the inches above 5 feet by 2.3 kg, then add 45.5 kg.
- IBW
- = ideal body weight in kilograms
- height
- = height in inches; divide centimetres by 2.54 first
- 60
- = 60 inches, equal to 5 feet
Both Devine equations use 2.3 kg for each inch above 5 feet. The male base is 50 kg and the female base is 45.5 kg, so the same height produces results that differ by 4.5 kg.
Optional clinical IBW comparisons
These are separate published height-weight equations. MedMaths keeps Devine as the primary answer and does not average the methods.
Robinson comparison — common rounded form
Male: IBW = 52 + 1.9 × (height in inches − 60)
Female: IBW = 49 + 1.7 × (height in inches − 60)
MedMaths uses the commonly reproduced rounded clinical form. The original Robinson paper reported more precise regression coefficients.
Miller (1983)
Male: IBW = 56.2 + 1.41 × (height in inches − 60)
Female: IBW = 53.1 + 1.36 × (height in inches − 60)
Miller is shown as a comparison estimate only; use it when the governing source specifically names that method.
Where the Devine IBW equation came from
The equations now commonly called the Devine ideal body weight formulas appeared in a 1974 Drug Intelligence & Clinical Pharmacy case study on gentamicin therapy. The original SAGE record lists Margaret M. McCarron, MD and Ben J. Devine, PharmD as the publication authors.
Later historical review by Pai and Paloucek traced the Devine equations to an older rule based on height-weight tables. That matters because the word “ideal” can be misleading: the equation is a historical clinical reference-weight estimate, not a measurement of lean mass and not a personalised healthy-weight target.
The formula is conventionally named for Devine, so MedMaths lists Ben J. Devine as the formula author while preserving Margaret McCarron’s role as co-author of the original publication.
Devine formula worked examples
Male example: 175 cm
Height (inches) = height (cm) ÷ 2.54
Height = 175 ÷ 2.54 = 68.8976 inches
Inches above 5 feet = 68.8976 − 60 = 8.8976
IBW (kg) = 50 + 2.3 × [height (inches) − 60]
IBW = 50 + 2.3 × 8.8976
IBW = 50 + 20.4646
IBW = 70.4646 kg
Unrounded formula result: 70.4646 kg. Displayed to one decimal place: 70.5 kg.
Female example: 160 cm
Height (inches) = height (cm) ÷ 2.54
Height = 160 ÷ 2.54 = 62.9921 inches
Inches above 5 feet = 62.9921 − 60 = 2.9921
IBW (kg) = 45.5 + 2.3 × [height (inches) − 60]
IBW = 45.5 + 2.3 × 2.9921
IBW = 45.5 + 6.8819
IBW = 52.3819 kg
Unrounded formula result: 52.3819 kg. Displayed to one decimal place: 52.4 kg.
Quick reference
Devine IBW by height
Use this table for a quick adult Devine IBW estimate at common heights. Values are calculated from the same formula as the calculator above and rounded to one decimal place. This is a clinical formula reference, not a healthy-weight or target-weight chart.
| Height | Height (cm) | Male Devine IBW | Female Devine IBW |
|---|---|---|---|
| 5 ft 0 in | 152.4 cm | 50 kg | 45.5 kg |
| 5 ft 2 in | 157.5 cm | 54.6 kg | 50.1 kg |
| 5 ft 4 in | 162.6 cm | 59.2 kg | 54.7 kg |
| 5 ft 6 in | 167.6 cm | 63.8 kg | 59.3 kg |
| 5 ft 8 in | 172.7 cm | 68.4 kg | 63.9 kg |
| 5 ft 10 in | 177.8 cm | 73 kg | 68.5 kg |
| 6 ft 0 in | 182.9 cm | 77.6 kg | 73.1 kg |
| 6 ft 2 in | 188 cm | 82.2 kg | 77.7 kg |
| 6 ft 4 in | 193 cm | 86.8 kg | 82.3 kg |
| 6 ft 6 in | 198.1 cm | 91.4 kg | 86.9 kg |
For heights between the rows shown, use the calculator so the exact entered height is used rather than interpolating between table values.
Important limitations of Devine IBW
- It is an estimate, not a body-composition measurement: Devine IBW does not measure fat mass, muscle mass or lean body mass.
- “Ideal” does not mean a personal target weight: the terminology comes from historical height-weight concepts and should not be used as an individual nutrition, fitness or obesity goal.
- It is not a universal medication-dosing weight: actual, ideal, adjusted and lean body-weight methods are medicine- and protocol-specific. Use the weight descriptor required by the current source.
- The 5-foot boundary is deliberate on MedMaths: the published equations are written as a base weight at 5 feet plus 2.3 kg per inch above 5 feet, so this calculator does not extrapolate the formula below 152.4 cm.
- Do not substitute it for ventilation predicted body weight: ventilation PBW is a protocol-defined construct. Some PBW protocols use coefficients numerically similar to Devine, but the protocol applicability and boundary rules remain separate.
- “IBW” does not always mean generic Devine: if a drug label or protocol gives its own IBW equation, use that equation rather than assuming this calculator is interchangeable.
Which body-weight measure does this page calculate?
Devine IBW
Devine is the default IBW result. Robinson and Miller may be shown as optional IBW comparisons, but they remain the same body-weight concept calculated by different equations.
Actual or adjusted weight
Actual weight is measured. Adjusted weight is a separate formula that uses actual weight and IBW. Neither is calculated here.
Ventilation PBW
Predicted body weight for ventilation is a protocol-defined construct. Some PBW equations use coefficients numerically similar to Devine, but you should still follow the ventilation protocol rather than substitute this medication-oriented IBW page automatically.
Ideal body weight FAQShowHide
What is the IBW formula for females?
Devine female IBW is 45.5 kg plus 2.3 kg for every inch of height over 5 feet.
- Over 5 feet means over 60 inches, or 152.4 cm.
- Use the equation the medication reference or protocol names.
A woman 165 cm tall is about 65 inches, which is 5 inches over 5 feet, so her Devine IBW is about 56.9 kg.
Is ideal body weight the same as predicted body weight on a ventilator?
Not necessarily. Ventilator protocols often use predicted body weight (PBW), which is also worked out from height and sex but is defined by the protocol. Use the formula your protocol names.
- Some PBW equations use the same base weights as Devine (50 kg male, 45.5 kg female) and about 0.91 kg for each cm over 152.4 cm.
- This calculator returns Devine IBW. It does not calculate ventilation predicted body weight.
Check your ventilator protocol for the exact equation before using any weight for tidal volumes.
What does IBW mean, and what does the result represent?
IBW means ideal body weight. Here it is the adult reference weight returned by the selected Devine equation from height and sex.
- The result is reported in kilograms.
- It is not measured body weight, a healthy-weight target, or a direct body-composition measurement.
- Use it only when the medication reference or clinical protocol specifically requires Devine IBW.
A 175 cm male adult has a Devine IBW of about 70.5 kg.
Which ideal body weight formula does this calculator use?
Devine is the default MedMaths result. You can optionally compare the common Robinson and Miller clinical IBW equations without replacing the Devine answer.
- Devine male: 50 + 2.3 × (height in inches − 60).
- Devine female: 45.5 + 2.3 × (height in inches − 60).
- Robinson and Miller use different base weights and per-inch increments, so their estimates can differ for the same height.
Male 5 ft 10 in: 50 + 2.3×10 = 73 kg.
Can I calculate Devine IBW using centimetres or feet and inches?
Yes. The calculator accepts either system and converts centimetres to inches using 1 inch = 2.54 cm before applying Devine.
- The measurement-system switch converts a valid entered height.
- The formula is then applied using the full, unrounded height conversion.
- The step-by-step working shows the conversion used.
175 cm ÷ 2.54 = 68.8976 inches before the Devine equation is applied.
Why can two IBW calculators give different results?
They may use a different IBW equation, a different version of that equation, or round height at a different stage.
- Devine, Robinson, Miller, and Hamwi use different constants and are not interchangeable.
- MedMaths keeps Devine as the primary result and offers Robinson and Miller only as optional comparison estimates.
- Use the named method required by the relevant clinical reference rather than averaging formulas.
At the same height, Devine, Robinson and Miller can return different kilogram estimates because the equations are different.
When should ideal body weight be used for medication calculations?
Only when the medicine information, prescription, pharmacist, or local protocol specifies ideal body weight or the Devine method.
- Many medicines use actual body weight instead.
- Some medicine-specific protocols use adjusted body weight.
- This calculator does not select the correct body-weight measure for a medicine.
Do not replace a prescribed actual-weight calculation with IBW simply because IBW is available.
If a drug label says ideal body weight, can I assume it means the MedMaths Devine formula?
No. Use the exact IBW equation or dosing-weight method named by the active drug label, protocol, study, or pharmacist guidance.
- Some U.S. product labels use the term ideal body weight without asking MedMaths to choose a formula.
- Other labels provide their own explicit IBW or adjusted-IBW equation, which can differ from the generic Devine implementation on this page.
- Do not substitute a generic Devine result when the governing source defines a different equation.
BUSULFEX labeling provides its own IBW method, so follow that source rather than assuming every mention of IBW means generic Devine.
Why does this calculator stop below 5 feet (152.4 cm)?
The Devine equations use 5 feet as their reference point, and this clinical calculator does not extrapolate them below that height.
- Some clinical tools and protocols restrict Devine IBW to people at least 60 inches tall.
- Short-stature policies can differ between organisations and calculations.
- Use the method explicitly specified by the applicable protocol.
A height of 150 cm is below this calculator's supported Devine range.
Is Devine IBW the same as actual, adjusted, or predicted body weight?
No. These are separate body-weight measures and may use different inputs and equations.
- Actual body weight is measured on a scale.
- Adjusted body weight is a separate medicine-specific calculation that uses actual weight and IBW.
- Ventilation predicted body weight is a protocol-defined construct and is not calculated here; some PBW protocols use coefficients numerically similar to Devine, but the clinical application and protocol rules are separate.
A Devine IBW result should not be copied into a ventilation PBW field unless the protocol explicitly says to do so.
Can this adult Devine calculator be used for children?
No. It is an adult clinical IBW calculator and is not a paediatric growth or dosing tool.
- Children and adolescents require age- and growth-specific methods.
- Do not substitute adult Devine IBW for a paediatric dosing policy.
- Follow the prescription, product information, and local paediatric protocol.
A paediatric mg/kg order normally begins with the prescribed paediatric weight method, not adult Devine IBW.
Need to understand why a dosing source might choose IBW, AdjBW or actual weight? Read Ideal vs adjusted body weight for medication dosing →
Continue calculating
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Open calculatorAdjusted Body Weight Calculator
Calculate Devine + 0.4 adjusted body weight (AdjBW), with actual weight shown as a percentage of IBW for source-specific threshold comparison.
Open calculatorReferences and sources
Open the Devine, Robinson and Miller source publications plus supporting clinical references used for this calculator.
References and sources
Open the Devine, Robinson and Miller source publications plus supporting clinical references used for this calculator.
Original publication and formula history
McCarron MM, Devine BJ — Clinical Pharmacy: Case Studies: Case Number 25 Gentamicin Therapy
Original articleDrug Intelligence & Clinical Pharmacy (1974); 8(11):650–655
The 1974 case-study publication in which the equations now commonly called the Devine IBW formulas appeared. SAGE lists Margaret M. McCarron first and Ben J. Devine second as publication authors.
Pai MP, Paloucek FP — The origin of the ideal body weight equations
Historical reviewAnn Pharmacother (2000); 34(9):1066–1069
Historical review explaining the origins of the Devine and other IBW equations, and why IBW should not be treated as synonymous with lean body weight.
Robinson JD, et al. — Determination of ideal body weight for drug dosage calculations
Original studyAm J Hosp Pharm (1983); 40(6):1016–1019
Study deriving Robinson height-weight equations from Metropolitan Life data. The original paper reports precise coefficients; the optional MedMaths comparison uses the commonly reproduced rounded clinical form.
Miller DR, et al. — Determining Ideal Body Weight (and Mass)
Original publicationAm J Hosp Pharm (1983); 40(10):1622–1627
1983 publication associated with the Miller height-weight IBW equation used as an optional comparison on MedMaths.
Peterson CM, et al. — Universal equation for estimating ideal body weight and body weight at any BMI
Modern reviewAm J Clin Nutr (2016); 103(5):1197–1203
Modern review tabulating the Devine, Robinson and Miller equations and demonstrating why different IBW formulas can return different estimates.
Current clinical context
Pharmacokinetics in Patients with Impaired Renal Function
FDA guidanceU.S. Food and Drug Administration
Current renal-impairment guidance noting that ideal or adjusted body-weight metrics may be used with Cockcroft-Gault in overweight or obese individuals when clinically appropriate.
Acyclovir Sodium Injection — professional labeling
U.S. drug labelDailyMed / U.S. National Library of Medicine
Medicine labelling provides a medicine-specific example in which obese adults are dosed using Ideal Body Weight, reinforcing that the active drug source determines the dosing-weight method.
BUSULFEX (busulfan) — professional labeling
U.S. drug labelDailyMed / U.S. National Library of Medicine
Medicine labelling defines its own IBW and adjusted-IBW methods, illustrating why a medicine-specific formula must take precedence over a generic Devine assumption.
Low-Tidal-Volume Ventilation facilitator guide
GovernmentAgency for Healthcare Research and Quality
Ventilation predicted body weight is a protocol-defined construct. Some low-tidal-volume PBW equations use coefficients numerically similar to Devine, but that does not make a medication-oriented IBW result a substitute for the ventilation protocol.
References are provided for education. Follow the medication reference, pharmacist guidance, and local clinical protocol.