Dosing
Creatinine clearance calculator
The renal-dosing number: Cockcroft-Gault creatinine clearance, with South African units first and the dosing caveats stated.
How to read the result
Creatinine clearance (mL/min) falls into these published bands.
A 75-year-old woman weighing 60 kg with a creatinine of 106 µmol/L (1.2 mg/dL).
CrCl 38 mL/min — reduced
Squarely in dose-adjustment territory for many renally cleared drugs, despite a creatinine that can read as unremarkable.
Who this is for
For prescribers adjusting renally cleared drugs — DOACs, low-molecular-weight heparins, aminoglycosides, and more — whose dosing references were validated against Cockcroft-Gault, not eGFR. Especially important in older patients, where a reassuring eGFR can hide a clearance low enough to change the dose.
How it works
What it calculates
Creatinine clearance by Cockcroft-Gault — the estimate against which most renal drug-dosing recommendations were originally validated.
When to use it
Renal dose adjustment (DOACs, aminoglycosides, LMWH and many more), especially in older patients where eGFR can look deceptively reassuring.
Weight matters
The formula uses actual body weight, which overestimates clearance in obesity — many references recommend adjusted body weight (IBW + 40% of the excess) when actual weight exceeds ideal by more than 20%. Pair with the IBW tool.
Built on published evidence
- CrCl = (140 − age) × weight / (72 × SCr) × 0.85 if female. Reference: Cockcroft & Gault 1976
Codification last reviewed 2026-08-28, and checked against published reference values in automated tests on every release — see the full evidence ledger.
Questions clinicians ask
CrCl or eGFR — which one for drug dosing?
Most drug references (DOACs prominently) were validated against Cockcroft-Gault creatinine clearance, so use CrCl for those decisions. eGFR is normalised to 1.73 m² and is the right tool for CKD staging.
Which weight should I enter?
The formula uses actual body weight, which overestimates clearance in obesity — many references recommend adjusted body weight (ideal plus 40% of the excess) when actual exceeds ideal by more than 20%. The IBW tool in the app pairs with this one.
Is it valid in acute kidney injury?
No — like all creatinine-based estimates it assumes a steady state. In AKI the creatinine is still moving, and the true clearance is usually worse than the number suggests.
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