About

The estimated Glomerular Filtration Rate (eGFR) is the gold standard for assessing renal function. This calculator implements the 2021 CKD-EPI Creatinine Equation, recommended by the National Kidney Foundation and the American Society of Nephrology. Unlike older formulas, this updated standard removes race as a variable to ensure equitable clinical assessment for all patient populations.

Early detection of Chronic Kidney Disease (CKD) allows for interventions that can slow progression. This tool interprets Serum Creatinine levels relative to age and biological sex to categorize kidney function into one of five stages, from normal function (Stage 1) to kidney failure (Stage 5).

Formulas

The 2021 CKD-EPI equation calculates eGFR based on serum creatinine (S_cr), age, and sex using the following logic:

eGFR = 142 × min(S_crκ, 1)^α × max(S_crκ, 1)^-1.200 × 0.9938^Age × F

{

Female: κ = 0.7, α = -0.241, F = 1.012Male: κ = 0.9, α = -0.302, F = 1

Reference Data

Stage	eGFR Range (mL/min/1.73m²)	Clinical Description
1	≥ 90	Normal or high function (if other signs of kidney damage are present)
2	60 to 89	Mildly decreased function
3a	45 to 59	Mildly to moderately decreased
3b	30 to 44	Moderately to severely decreased
4	15 to 29	Severely decreased function
5	< 15	Kidney failure (End Stage Renal Disease)

Frequently Asked Questions

The MDRD study equation was the previous standard but is known to underestimate eGFR in healthy individuals. The 2021 CKD-EPI equation provides better accuracy across a broader range of kidney function and age groups.

Historically, equations included a coefficient for Black individuals. However, the 2021 consensus by the NKF and ASN determined that removing the race variable leads to more unbiased clinical decisions and diagnosis.

Yes. Serum creatinine can fluctuate based on hydration, protein intake, and muscle mass. A single abnormal result should usually be confirmed with a repeat test or additional markers like Cystatin C.

This tool accepts mg/dL (standard in the US) and automatically handles the calculation. If your lab results are in µmol/L (international standard), you must convert them first: divide µmol/L by 88.4 to get mg/dL.