GFR Calculator (2021 CKD-EPI)
Estimate adult eGFR from age, sex and serum creatinine using the race-free 2021 CKD-EPI creatinine equation.
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Change any assumption and calculate again to compare results.
2021 race-free CKD-EPI equation
The National Kidney Foundation recommends the 2021 CKD-EPI creatinine equation for estimating GFR in adults from standardized serum creatinine, age and sex. The equation does not include race.
This calculator implements the published constants directly. If creatinine is entered in micromoles per litre, it is converted to mg/dL before calculation. The result is expressed as mL/min/1.73 m².
How to interpret the category label
The calculator also shows the common GFR category: G1 at 90 or above, G2 at 60–89, G3a at 45–59, G3b at 30–44, G4 at 15–29 and G5 below 15.
A category by itself does not diagnose chronic kidney disease. The National Kidney Foundation notes that G1 or G2 without evidence of kidney damage does not meet CKD criteria. Persistence over time, urine albumin and clinical context matter.
Important limitations
eGFR is an estimate, not a direct measurement. Creatinine can be affected by muscle mass, diet, medications and acute illness. The equation is intended for adults and should not replace a laboratory report or clinician interpretation.
Do not use this page to make medication, dialysis or emergency-care decisions. If a result is unexpectedly low or changing quickly, discuss the laboratory value with a healthcare professional.
Important information
This calculator is for general education and planning. It is not a diagnosis, medical device or substitute for individualized healthcare advice. Measurements and formula estimates can differ from clinical assessments.
If the result could affect treatment, pregnancy care, medication, driving, military status or another safety-sensitive decision, confirm it with the appropriate qualified professional or official process.
Frequently Asked Questions
Which GFR formula does this use?
The race-free 2021 CKD-EPI serum-creatinine equation for adults.
Does eGFR alone diagnose CKD?
No. Kidney-damage markers, persistence over time and clinical context are also important.
Can I enter creatinine in µmol/L?
Yes. Choose µmol/L and the calculator converts the value before applying the equation.