Health & Fitness

Ideal Body Weight Calculator

Calculate your ideal body weight using 5 evidence-based formulas: Devine, Robinson, Miller, Hamwi, and BMI-based ranges.

cm or ft in

What Is Ideal Body Weight?

Ideal Body Weight (IBW) is a concept used in medicine and pharmacy to estimate the weight at which a person's health risks are minimised, or to calculate medication doses that are based on lean body mass rather than total weight.

Unlike BMI, which considers only height and weight, IBW formulas are typically based on height, sex, and frame size. There is no single universally accepted formula — different medical fields use different ones depending on their purpose.

The Five IBW Formulas Explained

  • Devine Formula (1974): The most widely used in clinical practice, especially for calculating drug dosing in pharmacy. Originally developed for creatinine clearance calculations.
  • Robinson Formula (1983): A modification of Devine's formula that produced slightly lower estimates, considered more appropriate for general weight management guidance.
  • Miller Formula (1983): Another modification with slightly higher values than Robinson, sometimes used in pulmonary medicine.
  • Hamwi Formula (1964): One of the oldest formulas, originally developed for diabetes management. Uses a different base weight and increment per inch.
  • BMI-Based Range (18.5–24.9): Rather than a single number, this gives the full healthy weight range for your height based on WHO BMI classifications.

Limitations of IBW Formulas

All IBW formulas have significant limitations when applied as personal weight targets:

  • They were developed from population statistics, not as individual targets
  • They do not account for body composition (muscle vs. fat), age, or ethnic differences
  • Athletes and muscular individuals will appear "overweight" by these formulas
  • The formulas break down for people below 5 feet (152 cm) tall

Important: Use these numbers as context, not as strict goals. Consult a healthcare professional before making significant changes to diet or exercise based on any weight metric.

Medical Disclaimer: This calculator is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making health decisions.

Frequently Asked Questions

Which ideal weight formula is most accurate?
There is no single most accurate formula — they were developed for different clinical contexts. The BMI-based range (18.5–24.9) is the most commonly used by healthcare providers for general weight assessment. For medication dosing, the Devine formula is standard.
Is ideal body weight the same as healthy weight?
Not exactly. IBW formulas give a single number, while "healthy weight" is typically expressed as a range (the BMI 18.5–24.9 range). The IBW single number usually falls within this healthy range but doesn't account for individual body composition differences.
Why do men and women have different ideal weights?
Women generally have a higher percentage of body fat and lower muscle mass than men at the same height. IBW formulas account for this by using different base values and increments per inch above 5 feet.
Can I use this calculator if I'm under 5 feet tall?
The Devine, Robinson, Miller, and Hamwi formulas were designed for heights above 5 feet (152 cm) and may give inaccurate or even negative results below this threshold. The BMI-based range is still valid for any height.
What should I do if my weight is above my "ideal" weight?
First, consult a healthcare professional — weight goals should be personalised. General guidance: a moderate calorie deficit (300–500 kcal/day below TDEE) combined with strength training preserves muscle while reducing fat. Gradual weight loss (0.5 kg/week) is more sustainable than aggressive cutting.