Ideal Body Weight (IBW) Calculator
Calculate IBW in kilograms using the Devine formula (male/female) with worked examples, practice questions, FAQs, and references.
Important: This is a clinical IBW calculator (a height-based estimate used in some ICU and dosing contexts). It is not a “healthy target weight” tool and does not measure body fat. Follow local protocol for which weight metric to use (Actual, IBW, or Adjusted).
Commas accepted (e.g., 1,750). Press Enter to calculate.
Actual weight (optional)
This does not change IBW — it only adds an optional comparison.
Commas accepted. Leave blank if you don’t want the comparison.
Educational use only. Always interpret results in clinical context and follow local policy/protocols.
How to calculate IBW
Ideal body weight (IBW) is a height-based estimate. In practice, it’s used when a protocol asks for a standardized weight that is less influenced by adipose mass than total body weight (TBW). Examples include some drug-dosing guidance and some ICU workflows.
This page uses the Devine equation. To compute it reliably:
- Step 1: Convert height from cm → inches using in = cm ÷ 2.54
- Step 2: Compute inches over 60: (in − 60)
- Step 3: Apply the Devine formula for male or female.
- Step 4: Follow your workplace’s rounding policy (e.g., 0.1 kg or 0.5 kg).
Quick note on common queries: “Female IBW” uses the same structure, but the base constant changes (45.5 kg). “Predicted body weight (PBW)” in ventilation protocols is also height-based and may use a cm-based coefficient.
Formula
IBW formula in cm (quick estimate)
Some people search for “ideal body weight formula in cm”. You can derive an approximate cm-form from Devine (because 2.3 ÷ 2.54 ≈ 0.9055):
Use the cm→inches method for exact consistency with protocols. Shortcut formulas can differ slightly due to rounding.
Predicted Body Weight (PBW) note (ventilation)
If your search is about “predicted body weight”, many ventilation protocols use a cm-based PBW formula. Always follow your ICU guideline (especially for patients < 5 feet).
Worked examples
Example 1 (Male): Height 175 cm
Answer: 70.5 kg
Example 2 (Female): Height 160 cm
Answer: 52.4 kg
Practice questions
Designed for student nurses, junior doctors, and pharmacists who want to verify their steps. Try it first, then reveal the answer and working.
Practice 1: Male, height 175 cm. What is IBW (kg) using Devine (to 1 decimal)?
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Answer: 70.5 kg
Practice 2: Female, height 160 cm. What is IBW (kg) using Devine (to 1 decimal)?
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Answer: 52.4 kg
Practice 3: Male, height 190 cm. What is IBW (kg) using Devine (to 1 decimal)?
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Answer: 84.0 kg
Practice 4: Female, height 182 cm. What is IBW (kg) using Devine (to 1 decimal)?
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Answer: 72.3 kg
Practice 5: Female, height 150 cm. What happens with Devine when height is under 60 inches?
Show answer + working
Answer: 43.3 kg
Clinical safety note
IBW is an estimate used in some protocols. Always confirm which weight metric your guideline requires (actual, ideal, adjusted, or PBW) and follow local pharmacy/ICU protocols, including rounding rules.
Related calculators
FAQs
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.
References & Sources
Primary & historical context
Pai MP, Paloucek FP — The origin of the “ideal” body weight equations
PubMedAnn Pharmacother (2000)
Historical perspective on where common IBW equations came from and why sources differ.
Peterson CM et al. — Universal equation for estimating ideal body weight
PMCAm J Clin Nutr (2016)
Compares multiple IBW equations (including Devine) and provides broader context.
Clinical use (ventilation / PBW)
ARDSNet trial — Lower tidal volume ventilation (PBW formula in methods)
JournalNEJM (2000)
Landmark ARDS ventilation strategy paper that defines PBW using height-based formulas.
MPOG chart — IBW / tidal volume chart (PBW formula, cm-based)
PDFMichigan Program on Value Enhancement
Quick reference chart showing PBW formulas in cm and guidance for patients < 5 feet.
Bedside calculators & summaries
MDCalc — Ideal Body Weight & Adjusted Body Weight
ClinicalMDCalc
Widely used bedside reference summarizing IBW/AdjBW equations and common use-cases.
ClinCalc — Ideal, Adjusted, and Nutritional Body Weight
ClinicalClinCalc.com
Clear explanation of IBW and related weight metrics (including adjusted approaches).
References are provided for education. Always follow local protocol and pharmacist/ICU guidance.