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Ideal Weight Calculator

Ideal Body Weight (IBW) was originally conceptualized by pharmacologists and clinicians to estimate lean body mass for drug clearance calculations. Ra

Health & Fitness
Published ideal body weight equations contain sex-specific baseline constants
Select preferred unit system
Standing height (cm in metric, inches in imperial)
Current weight (kg in metric, lb in imperial) for reference comparison
Formula & Methodology
Devine (1974): Men = 50.0 kg + 2.3 kg/in over 5ft; Women = 45.5 kg + 2.3 kg/in | Robinson (1983): Men = 52.0 + 1.9 kg/in; Women = 49.0 + 1.7 kg/in

Published IBW formulas begin with a baseline weight at 5 feet (60 inches) of height and add an incremental weight factor for each additional inch. Because the equations were derived on different historical cohorts, their outputs vary by several percent. Presenting the range between formulas accurately reflects physiological diversity.

Ideal Body Weight Reference Range (69–72 kg)

68.7 – 72.0 kg kg

Overview

Ideal Body Weight (IBW) was originally conceptualized by pharmacologists and clinicians to estimate lean body mass for drug clearance calculations. Rather than asserting a single rigid "ideal" number, this Ideal Weight Calculator synthesizes the four most widely cited published equations—Devine, Robinson, Miller, and Hamwi—alongside the World Health Organization healthy BMI interval to provide an evidence-based reference range.

Educational & Health Disclaimer: This calculator provides generalized statistical ranges from historical published equations. It is not medical advice, does not prescribe a target weight, and does not evaluate personal body composition. A healthy weight depends on muscle mass, bone density, age, and individual metabolic health. Consult a physician or registered dietitian for personal guidance.

Worked Examples

Male Adult at 175 cm (68.9 inches)

Male, Height = 175 cm (68.9 in), 8.9 inches over 60 in.

  1. Inches over 5 feet: 68.9 − 60 = 8.9 in.
  2. Devine formula: 50.0 + (2.3 × 8.9) = 50.0 + 20.47 = 70.5 kg (155.4 lb).
  3. Robinson formula: 52.0 + (1.9 × 8.9) = 52.0 + 16.91 = 68.9 kg (151.9 lb).
  4. Miller formula: 56.2 + (1.41 × 8.9) = 56.2 + 12.55 = 68.8 kg (151.7 lb).
  5. Hamwi formula: 48.0 + (2.7 × 8.9) = 48.0 + 24.03 = 72.0 kg (158.7 lb).
  6. Reference Range: 68.8 kg to 72.0 kg (151.7 to 158.7 lb).
Final Answer: 68.8 – 72.0 kg (151.7 – 158.7 lb)

Female Adult at 165 cm (65.0 inches)

Female, Height = 165 cm (65.0 in), 5.0 inches over 60 in.

  1. Inches over 5 feet: 65.0 − 60 = 5.0 in.
  2. Devine formula: 45.5 + (2.3 × 5.0) = 45.5 + 11.5 = 57.0 kg (125.7 lb).
  3. Robinson formula: 49.0 + (1.7 × 5.0) = 49.0 + 8.5 = 57.5 kg (126.8 lb).
  4. Miller formula: 53.1 + (1.36 × 5.0) = 53.1 + 6.8 = 59.9 kg (132.1 lb).
  5. Hamwi formula: 45.5 + (2.2 × 5.0) = 45.5 + 11.0 = 56.5 kg (124.6 lb).
  6. Reference Range: 56.5 kg to 59.9 kg (124.6 to 132.1 lb).
Final Answer: 56.5 – 59.9 kg (124.6 – 132.1 lb)

Imperial Evaluation: Male at 6 feet (72 inches)

Male, Height = 72 in (12 inches over 60 in).

  1. Devine: 50.0 + (2.3 × 12) = 77.6 kg (171.1 lb).
  2. Hamwi: 48.0 + (2.7 × 12) = 80.4 kg (177.3 lb).
  3. Range spans 165 lb to 177 lb across formulas.
Final Answer: 74.8 – 80.4 kg (164.9 – 177.3 lb)

How to Use This Calculator

  1. Select your biological sex to load the corresponding baseline coefficients.
  2. Choose metric (cm/kg) or imperial (in/lb) units.
  3. Enter your exact standing height and optional current weight.
  4. Examine the resulting reference range across Devine, Robinson, Miller, and Hamwi equations.

Frequently Asked Questions

Why do the Devine, Robinson, Miller, and Hamwi equations give different numbers?
Each equation was formulated by different medical researchers analyzing different population cohorts. Dr. Hamwi developed his rule of thumb in 1964; Dr. Devine adapted it in 1974 for drug dosing; and Robinson and Miller modified the slope in 1983 based on empirical insurance mortality tables. Their disagreement demonstrates that biological weight is a distribution rather than a single fixed number.
Is my ideal weight the weight I should force myself to reach?
No. These equations are statistical reference models originally created for clinical drug dosing (such as aminoglycosides and theophylline). They do not account for muscle mass, skeletal frame, ethnic background, or personal athletic training.
How does frame size affect ideal body weight?
Traditional anthropometry suggests that individuals with a small wrist circumference / skeletal frame sit approximately 10% below formula averages, while individuals with a broad frame sit approximately 10% above.
Which formula is most commonly used in hospitals?
The Devine formula (1974) is by far the most widely utilized in clinical pharmacology for determining weight-based medication dosages in renally cleared medications and mechanical ventilation tidal volumes.
How does the WHO healthy BMI range compare to ideal weight formulas?
The WHO healthy BMI range (18.5 to 24.9 kg/m²) provides a much wider, more realistic population interval (typically spanning 15 to 20 kg for an average adult), accommodating variations in body fat and muscle.

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Reviewed & Authored by: OnlineConvers Health & Quantitative Science Editorial Team · Last Updated: 2026-10-07
Evaluates published pharmacological Ideal Body Weight formulas across a 60-inch (5-foot) baseline: Devine (1974) [M: 50 + 2.3/in, F: 45.5 + 2.3/in]; Robinson (1983) [M: 52 + 1.9/in, F: 49 + 1.7/in]; Miller (1983) [M: 56.2 + 1.41/in, F: 53.1 + 1.36/in]; Hamwi (1964) [M: 48 + 2.7/in, F: 45.5 + 2.2/in]. Height conversions use the exact international constant 1 in = 2.54 cm. The composite output is presented as an evidence-based reference range.
Citations: Gentamicin therapy in clinical practice (Current Therapeutic Research (Devine BJ, 1974)) · Determination of ideal body weight for drug dosage calculations (American Journal of Hospital Pharmacy (Robinson JD et al. 1983)) · Compilation of comparison of formulas for ideal body weight (International Journal of Clinical Pharmacy (Miller DR et al. 1983)) · Changing dietary concepts: The Hamwi formula (Diabetes Outlook (Hamwi GJ, 1964))