Creatinine Clearance Calculator (Cockcroft–Gault)
Estimated creatinine clearance in mL/min from age, weight, sex and serum creatinine, the equation behind many drug-dosing tables.
Results
What this tool does
Cockcroft and Gault published this equation in 1976 and it is still the one most drug leaflets use to adjust doses for reduced kidney function. It assumes a steady creatinine, falls with age because muscle mass does, and takes 15 % off for women. The weight matters: in people who are markedly overweight or underweight, clinicians often use ideal or adjusted weight instead of actual weight. Modern lab reports quote eGFR from the CKD-EPI equation, which is normalised to body surface area and gives different numbers, so the two are not interchangeable.
Formula
CrCl = (140 − age) × weight ÷ (72 × creatinine) · × 0.85 for women (creatinine in mg/dL, weight in kg)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
ag | Age | a |
kg | Body weight | kg |
sc | Serum creatinine | — |
u | Unit of the creatinine value | — |
sx | Sex | — |
CG | Creatinine clearance (Cockcroft–Gault) | mL/min |
CS | The same in mL/s | mL/s |
MG | Creatinine in mg/dL | mg/dL |
UM | Creatinine in µmol/L | µmol/L |
Worked example
- Age60 a
- Body weight75 kg
- Serum creatinine1
- Unit of the creatinine value1
- Sex1
- Creatinine clearance (Cockcroft–Gault)83.3 mL/min
- The same in mL/s1.39 mL/s
- Creatinine in mg/dL1.00 mg/dL
- Creatinine in µmol/L88 µmol/L
Limitations
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.