Ideal Weight Calculator
Estimate ideal body weight using the Devine and Robinson formulas based on height and sex.
About the Ideal Weight Calculator
Ideal body weight formulas were originally developed for medical dosing calculations but are widely used today as a general reference point for a healthy weight range based purely on height and sex. This calculator applies two well-known formulas, Devine and Robinson, for comparison.
How It Works
Both formulas start from a base weight for 5 feet of height and add a fixed amount for every inch over that, with different constants for men and women reflecting typical frame differences. The calculator converts your height to inches, applies both formulas, and returns each result.
Devine (kg) = (50 male / 45.5 female) + 2.3 × inches over 5 feet. Robinson (kg) = 52 + 1.9 × inches over 5 feet for men, or 49 + 1.7 × inches over 5 feet for women.
Worked example
Scenario: A man who is 175 cm (68.9 inches) tall.
- Inches over 5 feet: 68.9 − 60 = 8.9.
- Devine: 50 + 2.3 × 8.9 = 70.5 kg.
- Robinson: 52 + 1.9 × 8.9 = 68.9 kg.
Result: About 70.5 kg (Devine) and 68.9 kg (Robinson).
Tips and common mistakes
- For women the formulas start lower: Devine 45.5 kg + 2.3 kg per inch, Robinson 49 kg + 1.7 kg per inch.
- These formulas were created for drug dosing, not as personal weight targets.
- The BMI Calculator shows the healthy weight range for your height, which is usually more useful than a single number.
Assumptions & Limitations
- These formulas were developed decades ago primarily for clinical medication dosing, not as a fitness or aesthetic target.
- Assumes a medium body frame; larger or smaller frame sizes would reasonably fall outside these formulas' single-point estimate.
- Ideal weight formulas do not account for muscle mass, bone density, or individual body composition, and should be treated as a rough reference, not a personal goal.
- Different formulas (Devine, Robinson, Miller, Hamwi) all give somewhat different answers for the same height, illustrating that there is no single 'correct' ideal weight.
Why there is no single ideal weight
Devine and Robinson are historical height-based equations, so their outputs should be treated as reference estimates—not medically defined “ideal” targets. They do not incorporate body composition, waist size, health history, fitness, or laboratory measures.
For general adult screening, a BMI-based healthy-weight range provides a range rather than one target number. Even that range is only one part of health assessment.
Sources and review
Method: Devine and Robinson formulas: base weight at 5 ft plus a fixed amount per additional inch.
Sources:
- Devine BJ. Gentamicin therapy. Drug Intelligence and Clinical Pharmacy, 1974;8:650–655.
- Robinson JD, Lupkiewicz SM, Palenik L, et al. Determination of ideal body weight for drug dosage calculations. American Journal of Hospital Pharmacy, 1983;40:1016–1019.
Last reviewed: October 2026 by Faheem Ali, founder of CalculatorAnything. The method and examples are provided for transparency; results remain estimates and may contain errors.
Results are estimates for general information and screening, not a diagnosis or medical advice. Talk to a qualified healthcare professional before making health or diet decisions. Spotted an error? Tell us — see our editorial policy for how corrections are handled.