Creatinine Clearance Calculator
Estimate adult CrCl with the Cockcroft–Gault equation using age, equation weight and serum creatinine. See the arithmetic and optionally compare a second weight assumption.
Estimated CrCl is not a medicine dose. Results are in mL/min. This tool does not choose the appropriate weight, diagnose CKD or replace a prescriber’s assessment.
Use the calculatorCalculate CrCl With an Explicit Weight Assumption
Use a serum creatinine laboratory result. The equation assumes stable creatinine; weight selection and clinical suitability require care, especially at extremes of body size.
Your CrCl estimate will appear here
Identify the weight assumption, enter the laboratory creatinine value and check its units. The result is an estimate, not a treatment decision.
The weight assumption matters
This equation scales directly with its weight input. A comparison does not identify which convention is right for you.
CrCl and eGFR differ
This result is estimated CrCl in mL/min, not indexed eGFR in mL/min/1.73 m².
No automatic medicine advice
The tool does not select a dose, label a medicine safe or assign a CKD stage.
Your estimated creatinine clearance
mL/min · estimated CrCl, not indexed to 1.73 m²
Alternative-weight comparison
Review before acting: This number alone cannot diagnose kidney disease, select a medicine dose or prove that a weight assumption is suitable. Discuss new, unexpectedly low or changing laboratory results with your care team.
View inputs and arithmetic ↓Medical disclaimer: This is an educational Cockcroft–Gault estimate, not measured clearance or a prescribing recommendation. Do not rely on it for children, pregnancy, acute kidney injury, rapidly changing creatinine or dialysis. Body composition, fluid retention and laboratory methods can affect interpretation. Do not change medicines, fluids or diet from this result; ask your clinician or pharmacist which kidney-function estimate and weight convention apply.
Trace the Cockcroft–Gault arithmetic
| Step | Calculation | Value |
|---|
How age, weight and creatinine form the estimate
Review the exact equation and load all three examples to check the inputs and outputs.
Estimated CrCl (mL/min) = [(140 − age in years) × equation weight in kg] ÷ [72 × serum creatinine in mg/dL] × sex factor
| Quantity | Implementation | What to check |
|---|---|---|
| Age | Completed whole years; 140 − age is the numerator term. | This page accepts adult inputs only. |
| Equation weight | The entered primary weight converted to kg. | The weight-basis label records your choice; it does not change or validate the weight. |
| Serum creatinine | Use mg/dL; divide a µmol/L value by 88.4. | No automatic rounding up to 1 mg/dL. |
| Sex factor | Male coefficient 1; female coefficient 0.85. | A historical equation adjustment, not a measured personal correction. |
| Output | Estimated CrCl in mL/min, rounded to one decimal. | No body-surface-area indexation, stage or dose is added. |
Original equation: Cockcroft and Gault, Nephron (1976). Practical interpretation and an independent example: NHS Specialist Pharmacy Service.
Age 60 · 70 kg · male coefficient
With serum creatinine 1.00 mg/dL, the equation gives 77.8 mL/min. These are fictional inputs to demonstrate the arithmetic, not a normal-range target.
Same inputs · female coefficient
70 kg equivalent is loaded in lb and creatinine as 88.4 µmol/L. The ×0.85 factor gives 66.1 mL/min. Unit conversion does not account for that coefficient difference.
Age 80 · 120 µmol/L · two weights
At 60 kg with the male coefficient: 36.8 mL/min. Changing only the equation weight to 50 kg gives 30.7 mL/min. The 60 kg case reproduces the SPS example, which reports a rounded 37.
Interpret the weight assumption and the kind of kidney estimate
Keep the equation result separate from a diagnosis or prescribing decision.
| Result or test | Typical units | Why it is different |
|---|---|---|
| Estimated CrCl on this page | mL/min | Cockcroft–Gault calculation from age, weight, sex coefficient and serum creatinine. |
| Indexed eGFR on many lab reports | mL/min/1.73 m² | A different equation and body-size reference; the number cannot simply be relabelled as CrCl. |
| BSA-adjusted absolute eGFR | mL/min | Even with matching units, it remains estimated GFR rather than Cockcroft–Gault CrCl. |
| Measured creatinine clearance | mL/min, or indexed units if the lab specifies | Requires urine collection and laboratory measurements. This page does not perform that test. |
Which weight belongs in the equation?
A weight entered into the numerator directly changes the estimate. A clinician may specify actual, ideal or adjusted weight for a particular context. The basis selector is a label for the primary input, not an algorithm that chooses the weight. Do not infer a dosing rule from the default units.
What the optional comparison shows
The second result changes only the equation weight while holding age, creatinine and coefficient fixed. It illustrates sensitivity to an assumption. The two outputs are not a clinical uncertainty range, two test dates or competing treatment recommendations.
Current guidance is not one universal rule
NKF now supports moving medication-related decisions toward appropriately body-size-adjusted, race-free eGFR. UK MHRA guidance still names Cockcroft–Gault for specific prescribing circumstances. Use the relevant medicine information and local clinical guidance; this page cannot resolve that choice.
A low creatinine value is not automatically raised
The script uses your entered serum creatinine after unit conversion. It does not replace a value below 1 mg/dL with 1. Low muscle mass and other factors can make interpretation difficult, but inventing a higher creatinine value is not a general fix.
Stable creatinine is a prerequisite
A rapidly changing blood creatinine concentration can make this steady-state estimate misleading. This calculator is not for assessing acute kidney injury, dialysis or pregnancy, and it does not model recovery or future kidney function.
Body composition needs individual review
Fluid retention, amputation, muscle wasting and unusually high muscle mass can complicate a weight-and-creatinine model. Accepted inputs do not establish that the estimate suits the person. A pharmacist or clinician can assess a different measure when needed.
Do not translate CrCl into a CKD stage
This page intentionally provides no G1–G5 classification or “normal kidney” badge. An estimated creatinine clearance is not an indexed eGFR result, and CKD assessment involves duration and other evidence. See the separate eGFR tool for that named equation.
A dose threshold needs more than this number
Even when a drug’s instructions mention CrCl, the dose may depend on the indication, other medicines, test trend and the weight convention. The calculator does not identify a medicine, recommend a dose or decide whether treatment should stop.
Read the NKF discussion of Cockcroft–Gault limitations and current direction, MHRA prescribing guidance, and NIDDK’s kidney-function and drug-dosing overview. These sources describe clinical decisions; they do not endorse this calculator.
Related tools and original CrCl references
Follow the named equations and clinical sources when comparing a laboratory report or discussing a medicine.
Useful resources
Equation attribution: Cockcroft DW and Gault MH, Nephron 16:31–41 (1976). Bhavin Sheth is the page maintainer; independent medical review or clinical validation of this implementation is not claimed. A related weight calculator does not determine a suitable dosing weight.
Questions about equation weight, creatinine and CrCl
Check which assumptions the number depends on before comparing it with a report.
Which CrCl equation is used?
Cockcroft–Gault: [(140 − age) × equation weight in kg] ÷ [72 × serum creatinine in mg/dL], multiplied by 0.85 for the female coefficient or 1 for the male coefficient. The result is estimated creatinine clearance in mL/min.
Does the weight-basis selector calculate ideal or adjusted weight?
No. It records whether the primary input is actual weight or a clinician-selected equation weight. The entered number is used without an ideal-weight formula, adjusted-weight rule or automatic substitution.
What does the alternative-weight result mean?
It shows what the same equation returns if only the weight input changes. It is not a confidence interval, a recommendation to use either weight or a result from a second blood test.
How are pounds and µmol/L handled?
Pounds are multiplied by 0.45359237 to obtain kg. Creatinine in µmol/L is divided by 88.4 to obtain mg/dL. Switching a unit converts an already-entered measurement; select the unit first when typing a new value.
Does the calculator round low creatinine up to 1 mg/dL?
No. The entered value is used after unit conversion, within the stated software limits. The script does not apply an automatic creatinine floor of 1 mg/dL or an age-based replacement value.
Is this the same as eGFR or a 24-hour urine test?
No. Cockcroft–Gault estimates CrCl without urine collection. Indexed eGFR is a different calculation, usually reported per 1.73 m². Matching units alone do not make different kidney-function measures interchangeable.
Can the result tell me my CKD stage or medicine dose?
No. This page does not assign CKD stages, identify a medicine or recommend a dose. Ask your clinician or pharmacist which kidney-function measure and weight convention apply to the actual clinical decision.
Is Cockcroft–Gault required for every medicine?
No. Guidance and medicine information differ. NKF supports transition toward appropriately body-size-adjusted race-free eGFR for medication decisions, while UK MHRA guidance specifies Cockcroft–Gault in certain circumstances. Follow the relevant clinical guidance.
When should I avoid relying on this equation?
Do not rely on this adult implementation for children, pregnancy, dialysis or rapidly changing creatinine such as acute kidney injury. Extremes of body composition and fluid retention also need individual clinical interpretation.
Are my weight and laboratory entries saved or uploaded?
This calculator script keeps entries in browser memory without uploading them or saving them to browser storage. Fonts and other website scripts may make separate requests; the statement applies to this calculator script only.