GFR Calculator
0 mL/min/1.73m²
How This eGFR Calculator Works
This calculator estimates glomerular filtration rate (eGFR) using the CKD-EPI 2021 creatinine equation, the race-free formula now recommended by the National Kidney Foundation and American Society of Nephrology as the current clinical standard, replacing the older race-based CKD-EPI (2009) and MDRD equations. The formula combines serum creatinine, age, and sex using equation constants that differ by sex and by whether creatinine falls above or below a sex-specific threshold (0.7 mg/dL for women, 0.9 mg/dL for men), reflecting the non-linear relationship between creatinine and filtration rate.
Understanding CKD Stages
eGFR results are grouped into chronic kidney disease (CKD) stages: Stage 1 (90+, normal or high, but only a CKD stage if other kidney damage markers are present), Stage 2 (60-89, mildly decreased), Stage 3a (45-59), Stage 3b (30-44), Stage 4 (15-29, severely decreased), and Stage 5 (below 15, kidney failure). A single eGFR reading is a snapshot — nephrologists typically want to see the trend over at least two readings taken three or more months apart before diagnosing chronic kidney disease.
This Is an Estimate, Not a Diagnosis
eGFR is an estimate only. It can be affected by muscle mass, diet, hydration, pregnancy, acute illness, and certain medications, and it becomes less accurate at very high or very low creatinine values. This tool is for educational purposes and cannot replace a proper clinical evaluation — always discuss your kidney function and any test results with a doctor, who may also order additional tests such as a urine albumin-to-creatinine ratio (uACR) for a complete picture. If you're also tracking related health metrics, the BMI calculator and BMR calculator can round out a general wellness check, but neither substitutes for kidney-specific testing.
Frequently Asked Questions
What is a normal eGFR result?
An eGFR of 90 or above is generally considered normal kidney function, assuming there's no other evidence of kidney damage. Values between 60 and 89 are considered mildly decreased and may be normal for some older adults, while a sustained reading below 60 for three or more months is one of the criteria used to diagnose chronic kidney disease (CKD).
Why does this calculator ask for sex but not race?
The CKD-EPI 2021 equation used here is the current race-free clinical standard, adopted after research showed that including a race coefficient in earlier formulas (like the 2009 CKD-EPI or MDRD equations) could overestimate kidney function in Black patients and lead to delayed care. Sex is still a factor because average muscle mass, and therefore baseline creatinine production, differs between men and women.