Clinical & Hospital Pharmacy
Creatinine Clearance Calculator
Estimates creatinine clearance (Cockcroft-Gault) for renal drug dosing, with the CKD-EPI 2021 eGFR and the matching dose-adjustment tier.
Creatinine clearance (Cockcroft-Gault)
54.2mL/min
G3a (Mild-to-Moderate: 45–59 mL/min)
Patient details
Sex
Validated in adults (18 years and over).
Adult normal is about 0.6–1.2 mg/dL (53–106 µmol/L). 1 mg/dL = 88.4 µmol/L.
Actual (total) body weight today.
Needed for ideal and adjusted body weight.
Try an example patient
Dosing weight
Which weight goes into the Cockcroft-Gault equation.
Using: Ideal Body Weight (70.5 kg)
Results & working
Dosing recommendation
Renal dose-adjustment tiers
General tiers by CrCl. The patient's tier is highlighted.
> 50 mL/min · Normal / Mild
Patient tier100% standard maintenance dose. Standard intervals.
30 – 50 mL/min · Moderate Reduction
Reduce dose by 25–50% or extend dosing interval (e.g. q12h -> q24h).
15 – 29 mL/min · Severe Reduction
Reduce dose by 50–75% (e.g. Enoxaparin 1 mg/kg q24h, Cefepime 1g q24h).
< 15 mL/min · ESRD / Dialysis
Avoid renally cleared drugs if possible. Dose post-hemodialysis.
CrCl across ages 20–90
How Cockcroft-Gault falls with age if weight and creatinine stayed the same.
1. Cockcroft-Gault (1976)
CrCl (mL/min) = [(140 − age) × weight (kg)] ÷ [72 × SCr (mg/dL)] × 0.85 if female
2. Devine ideal body weight and adjusted body weight
Male IBW = 50.0 kg + 2.3 × (height in inches − 60)
Female IBW = 45.5 kg + 2.3 × (height in inches − 60)
AdjBW (40%) = IBW + 0.4 × (actual weight − IBW)
IBW is never taken below 50 kg (male) or 45.5 kg (female). Auto uses actual weight when it is below IBW, adjusted weight when it is more than 120% of IBW, and IBW otherwise.
3. CKD-EPI 2021 (race-free)
eGFR = 142 × min(SCr/κ, 1)^α × max(SCr/κ, 1)^−1.200 × 0.9938^age × 1.012 if female
κ = 0.7 (female) or 0.9 (male); α = −0.241 (female) or −0.302 (male). eGFR uses the measured SCr, not the 0.8 floor. µmol/L is divided by 88.4 and rounded to 0.01 mg/dL first. The stage shown on the result (G1–G5) is applied to the Cockcroft-Gault CrCl.
References: Cockcroft DW, Gault MH. Nephron 1976. Inker LA, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749.
Keep learning
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41.
Common questions
Most renal dose recommendations in drug labels were derived with Cockcroft-Gault CrCl in mL/min, so use it for dosing — especially for narrow-therapeutic-index drugs such as DOACs, aminoglycosides and enoxaparin. eGFR is indexed to 1.73 m² and is designed for staging chronic kidney disease.
There is no single agreed answer. A common approach, used by Auto here, is actual weight if the patient weighs less than their ideal weight, ideal weight if they are near it, and adjusted weight (IBW + 40% of the excess) if they weigh more than 120% of ideal. Follow your institution's policy.
Elderly and frail patients make little creatinine because they have little muscle, so a very low SCr can make CrCl look falsely high and lead to overdosing. Rounding up is a conservative habit, but it can also underestimate clearance — switch it off when you judge the low value to be genuine.
Not reliably. Creatinine lags behind a sudden change in kidney function, so any estimating equation will be wrong until creatinine is stable again. Use urine output, repeated creatinine and, where available, drug-level monitoring.
Switch the unit next to the creatinine field to µmol/L. The calculator divides by 88.4 to get mg/dL, which both equations need.
Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy