Ideal Body Weight Calculator
Estimate your ideal body weight using four established medical formulas, based on your height and sex.
Please Note:
The Ideal Body Weight Calculator provides general information only and is not a substitute for professional medical advice.
Please consult your GP or healthcare provider for personalised guidance about your health.
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About the Formulas
- Devine (1974): The most widely used formula in clinical medicine, originally designed for drug dosing calculations.
- Robinson (1983): A refinement of the Devine formula based on updated population data.
- Miller (1983): Tends to produce slightly lower estimates than Devine and Robinson.
- Hamwi (1964): A simple, quick-reference formula that has long been used in dietetics.
Frequently Asked Questions
Ideal body weight (IBW) formulas were originally developed to help calculate drug dosages, not to define a single "correct" weight. The most common formulas - Devine, Robinson, Miller and Hamwi - all estimate a healthy weight from your height and sex, and typically produce slightly different results.
No single formula is universally "most accurate" - they were derived from different population samples decades apart. The Devine formula is the most widely used in clinical practice today, particularly for medication dosing, but all four give a reasonable estimate. Averaging them, as this calculator does, smooths out the differences between individual formulas.
BMI-based healthy weight ranges (BMI 18.5-24.9) are calculated purely from height, while IBW formulas also factor in typical body proportions by sex. For taller or shorter people especially, the two methods can diverge - this is normal, and both are just estimates rather than precise targets.
Frame size adjustments are a common rule-of-thumb refinement (roughly -10% for a small frame and +10% for a large frame) that account for the fact that bone structure varies between people of the same height. It is not a precise science, but it can make the estimate feel more personalised.
Not necessarily. These formulas produce a single number, but healthy weight is really a range, and factors like muscle mass, age, and overall body composition matter too. Use this calculator as a general reference point rather than a strict target, and speak to a healthcare professional for personalised advice.
Disclaimer
This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment.
- Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition.
- Never disregard professional medical advice or delay seeking it because of information from this tool.
- Clinical decision-making should always incorporate the full clinical context, patient preferences, and local protocols.
- The creators of this tool accept no liability for decisions made based on its output.
If you are a patient: please discuss any results with your healthcare provider. This tool is designed for use by medical professionals and may not be appropriate for self-assessment.