GFR Calculator

What Is eGFR?

Estimated glomerular filtration rate (eGFR) measures how well your kidneys filter waste from your blood. It is calculated from your blood creatinine level, age, sex, and sometimes race, using the CKD-EPI 2021 equation, the current clinical standard. A normal eGFR is 90 or above. Lower values indicate reduced kidney function, which may require monitoring, treatment, or lifestyle adjustments to slow further decline.

eGFR Stages and What They Mean

Stage 1 (eGFR 90+): normal kidney function. Stage 2 (60–89): mildly reduced, often no symptoms. Stage 3a (45–59): mild to moderate reduction. Stage 3b (30–44): moderate to severe. Stage 4 (15–29): severe reduction, referral to a nephrologist is recommended. Stage 5 (below 15): kidney failure, dialysis or transplant may be needed. Many people with Stage 2 or early Stage 3 have no symptoms and discover reduced function through routine blood work.

How eGFR Is Calculated

The CKD-EPI 2021 equation uses serum creatinine, age, and sex. Creatinine is a waste product from normal muscle metabolism that your kidneys filter out. When kidney function declines, creatinine accumulates in the blood. This calculator applies the CKD-EPI formula to your lab values and classifies your result by CKD stage. Note that muscle mass, diet (especially high-protein intake), and hydration can temporarily affect creatinine levels and therefore the eGFR estimate.

The 2021 Race-Free eGFR Equation

Until 2021, the standard eGFR equations applied a separate coefficient for Black patients, which produced a higher reported eGFR for the same creatinine value. In 2021 a joint task force of the National Kidney Foundation and the American Society of Nephrology recommended dropping race from the calculation, and the CKD-EPI 2021 creatinine equation, which contains no race term, is now the US standard. For the same creatinine, the 2021 equation reports a somewhat lower eGFR for Black patients and a slightly higher one for others than the old race-based version. Where more precision is needed, the task force recommends confirming with a cystatin C test, a second blood marker that does not depend on muscle mass the way creatinine does.

eGFR vs Creatinine Clearance

These two are related but not the same. Creatinine clearance, often estimated with the older Cockcroft-Gault formula, measures how much blood the kidneys clear of creatinine per minute and can also be measured directly from a 24-hour urine collection. eGFR is a modeled estimate from a single blood draw. Most drug dosing references and CKD staging now use eGFR, but some medication package inserts still specify creatinine clearance, so the two are not interchangeable when a dose depends on it. When a lab reports your number, it is almost always eGFR from the CKD-EPI 2021 equation unless the order specified otherwise.

Protecting Kidney Health

Managing blood pressure and blood sugar are the two most important steps for preserving kidney function. High blood pressure and diabetes are responsible for roughly two-thirds of all chronic kidney disease cases. Staying hydrated, limiting sodium intake to under 2,300 mg per day, maintaining a healthy weight, and avoiding excessive use of NSAIDs (ibuprofen, naproxen) all support kidney health. If your eGFR is below 60, your doctor may recommend dietary protein adjustments and closer monitoring of kidney function over time.

Frequently asked questions