Printed on 3/17/2026
For informational purposes only. This is not medical advice.
Estimated glomerular filtration rate (eGFR) is the gold standard for assessing kidney function. This calculator uses the CKD-EPI 2021 equation — the latest race-free formula recommended by KDIGO — to estimate how well your kidneys filter waste based on serum creatinine, age, and sex. Results include CKD staging from G1 (normal) to G5 (kidney failure).
Formula: CKD-EPI 2021: 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.200 × 0.9938^Age × (1.012 if female)
Input your serum creatinine level from a recent blood test, along with your age and sex. Creatinine is measured in mg/dL (US) or μmol/L (international).
The CKD-EPI 2021 equation processes your values to estimate kidney filtration rate. Results are expressed in mL/min/1.73m², adjusted for body surface area.
Your eGFR maps to a chronic kidney disease stage (G1–G5). See what your stage means, when to see a nephrologist, and how to protect remaining kidney function.
Primary care physicians
Routine screening for chronic kidney disease in patients with diabetes, hypertension, cardiovascular disease (assess with [ASCVD Risk Calculator](/tools/ascvd-risk)), or family history of kidney failure. KDIGO recommends annual eGFR for at-risk populations.
Pharmacists & prescribers
Many medications require dose adjustment based on kidney function. eGFR guides dosing for metformin, DOACs, antibiotics, and nephrotoxic drugs to prevent accumulation and toxicity. For precise drug dosing calculations, use [Creatinine Clearance](/tools/creatinine-clearance).
Nephrologists
Serial eGFR measurements track CKD progression over months to years. A decline >5 mL/min/year is considered rapid progression and may warrant intensified management.
Radiologists & surgeons
eGFR is checked before contrast-enhanced imaging to assess risk of contrast-induced nephropathy. Prophylactic hydration protocols are guided by baseline kidney function.
Transplant teams
eGFR helps determine when to list patients for kidney transplant (typically eGFR <20) and is used to assess donor kidney function in living donor evaluation.
CKD patients
Patients with known kidney disease can track their eGFR trend between appointments to understand disease trajectory and the impact of lifestyle modifications.
This calculator uses the 2021 race-free equation recommended by KDIGO and NKF. Avoid older formulas (MDRD, CKD-EPI 2009 with race) which are now considered outdated.
CKD requires eGFR <60 or kidney damage markers (proteinuria, hematuria) sustained for ≥3 months. A single low eGFR may reflect acute illness, dehydration, or lab variation. Assess for acute metabolic issues with [Anion Gap](/tools/anion-gap) or [Corrected Calcium](/tools/corrected-calcium).
A stable eGFR of 55 is very different from an eGFR declining from 75→55 over one year. Plot serial values to identify rapid progressors who need aggressive intervention.
US labs report creatinine in mg/dL; international labs use μmol/L. The difference is ~88-fold. Entering the wrong unit produces wildly inaccurate eGFR.
In patients with extremes of muscle mass (bodybuilders, amputees, cachexia), cystatin C–based eGFR or a combined creatinine-cystatin C equation is more accurate.
eGFR is invalid in acute kidney injury (rapidly changing creatinine), pregnancy, children <18, and extreme body size. Use other assessments in these populations.
KDIGO staging uses both eGFR and albuminuria. Two patients with eGFR 50 have very different prognoses if one has UACR 30 vs. 300 mg/g. For patients with cirrhosis and CKD (hepatorenal syndrome), also calculate [MELD Score](/tools/meld-score).
Trimethoprim, cimetidine, and cobicistat inhibit tubular creatinine secretion, raising serum creatinine ~0.2 mg/dL without affecting true GFR. This causes falsely low eGFR.
KDIGO recommends nephrology referral for CKD G4–G5 (eGFR <30), rapid decline (>5 mL/min/year), or persistent significant proteinuria. Earlier referral improves outcomes. For patients with concurrent liver disease, calculate [MELD Score](/tools/meld-score) to assess transplant candidacy.
Blood pressure control, diabetes management, avoiding NSAIDs, and ACE inhibitor/ARB use are the pillars of CKD management. eGFR decline can be slowed significantly.
This calculator implements the CKD-EPI 2021 creatinine equation, recommended by KDIGO (Kidney Disease: Improving Global Outcomes), the National Kidney Foundation, and the American Society of Nephrology. The race-free equation was adopted following the 2021 NKF-ASN Task Force report on reassessing the inclusion of race in diagnosing kidney diseases.
Your eGFR result is reported in mL/min/1.73 m² and corresponds to a CKD stage. An eGFR of 90 or above (G1) indicates normal kidney function, though kidney disease may still be present if there are other markers such as proteinuria. An eGFR of 60–89 (G2) suggests mildly decreased function. Stage G3a (45–59) and G3b (30–44) represent moderate kidney function loss and are the stages where clinical management to slow progression becomes critical. Stage G4 (15–29) is severe loss, and G5 (below 15) indicates kidney failure where dialysis or transplant may be necessary.
A single eGFR value is a snapshot — kidney function should be confirmed with repeat testing over at least 3 months before diagnosing CKD. Trending eGFR over time is more clinically meaningful than any individual reading.
eGFR is used in routine screening for chronic kidney disease, particularly in patients with risk factors such as diabetes, hypertension, cardiovascular disease, or a family history of kidney failure. It is also essential when prescribing medications that are renally cleared, as many drugs require dose adjustments based on kidney function.
Clinicians use eGFR to monitor CKD progression over time, assess eligibility for nephrology referral (generally recommended at eGFR < 30 or with rapidly declining function), and guide decisions about dialysis planning.
eGFR equations estimate filtration from serum creatinine, which is influenced by muscle mass. The result may overestimate kidney function in patients with low muscle mass (e.g., elderly, malnourished, amputees) and underestimate it in very muscular individuals.
The CKD-EPI 2021 equation is validated for adults aged 18 and older and should not be used in children or pregnant women. Acute kidney injury (AKI) cannot be assessed with eGFR — when creatinine is rapidly changing, eGFR does not reflect real-time filtration.
Certain substances (e.g., trimethoprim, cimetidine) can elevate serum creatinine without affecting actual kidney function, producing a falsely low eGFR. Cystatin C–based equations may be preferred when creatinine-based estimates are unreliable.
For related assessments, see Creatinine Clearance, BUN/Cr Ratio and BSA Calculator.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
Calculate creatinine clearance (CrCl) using the Cockcroft-Gault equation. Used for renal drug dosing adjustments based on kidney function.
NephrologyCalculate the BUN/Creatinine ratio to distinguish pre-renal from intrinsic acute kidney injury. Normal ratio 10–20. Ratio >20 suggests pre-renal azotemia; <10 suggests intrinsic renal disease.
Body MetricsCalculate body surface area using Du Bois, Mosteller, and Haycock formulas. Free BSA calculator for chemotherapy dosing, cardiac index, and clinical calculations. BSA depends on weight — check [BMI Calculator](/tools/bmi-calculator).
PharmacyDetermine renal dose adjustment guidance by GFR stage for antibiotics, anticoagulants, metformin, NSAIDs, and 20+ drug classes. Based on current KDIGO CKD staging and prescribing guidelines.