Ideal Body Weight: Clinical Guide

Overview

The Devine formula estimates ideal body weight from height and sex. It was developed for dosing rather than defining a universally healthy target weight.

Clinical Significance

IBW may support dosing of selected medicines and calculations such as adjusted body weight. It should not be presented as an individual patient weight goal.

When to Use

• Use only where a protocol specifies ideal body weight.
• Use as an input to selected respiratory or pharmacokinetic calculations.
• Check whether the protocol specifies Devine or another equation.

How It Is Calculated

• Devine formula: male 50 kg and female 45.5 kg at 5 feet, plus 2.3 kg for each inch above 5 feet.
• For heights below 5 feet this implementation does not subtract weight below the base value.

Interpretation

• The result is an equation-derived dosing weight.
• It is not a direct measure of healthy body composition.
• Apply the result only within the relevant protocol.

Worked Example

A male adult who is 70 inches tall has an estimated IBW of 73 kg using the Devine formula.

Patient Considerations

• Body composition, age, ethnicity, disability, oedema and clinical condition are not represented by the equation.

Limitations

• The formula was not designed as a target body weight.
• It uses binary sex-specific constants.
• Different IBW equations produce different estimates.

Clinical Pearls

• Document the equation used.
• Use adjusted body weight only when the relevant protocol recommends it.
• Do not substitute IBW for measured weight without a clear indication.

Common Mistakes

• Treating IBW as a healthy-weight prescription.
• Using the wrong height unit.
• Assuming every medicine should be dosed using IBW.

Evidence Base

The Devine equation was introduced for aminoglycoside dosing and remains a commonly referenced IBW method, although its original evidence base was limited.

References

1. Peterson CM et al. Universal equation for estimating ideal body weight and body weight at any BMI. Am J Clin Nutr. 2016;103:1197–1203. — Independent review and comparison of established IBW equations, including Devine.
2. NICE guideline NG246: Overweight and obesity management — UK guidance on assessing and managing overweight, obesity and central adiposity.