Cockcroft-Gault Adjusted Body Weight Calculator

About this calculator

The Cockcroft-Gault equation estimates creatinine clearance (a proxy for kidney function/glomerular filtration rate) from age, weight, sex, and serum creatinine. In overweight or obese patients, however, using actual body weight overestimates renal function because excess fat mass doesn't contribute proportionally to creatinine production, so this calculator first computes the Devine ideal body weight (IBW) from height and sex, then uses an adjusted body weight — a weighted blend of IBW and actual weight — in place of raw weight in the Cockcroft-Gault formula.

This adjusted-weight approach is standard practice among pharmacists, nephrologists, and hospital clinicians when dosing renally-cleared medications (such as certain antibiotics, anticoagulants, and chemotherapy agents) for heavier patients, since using unadjusted actual weight in these cases can lead to overdosing and using ideal weight alone can underestimate true clearance — the adjusted figure balances both to better reflect real renal drug clearance.