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eGFR Calculator (CKD-EPI 2021)
Estimate glomerular filtration rate from serum creatinine, age, and sex using the race-free CKD-EPI 2021 creatinine equation, with instant KDIGO CKD stage classification.
Enter patient values
Use a steady-state serum creatinine (avoid samples from acute illness or rapidly changing renal function). Tap the unit badge to switch mg/dL ⇆ µmol/L.
years
This equation is validated for adults (age 18+). Results for pediatric patients are not reliable — use a pediatric (e.g. bedside Schwartz) equation instead.
Estimated GFR
– mL/min/1.73m²
–
G5
G3–G4
G1–G2
Scale capped for display at 120 mL/min/1.73m². A single result should be interpreted alongside trend, ACR, and clinical context — CKD is confirmed only when abnormalities persist >3 months.
KDIGO GFR Categories
G1
≥90
Normal or high
G2
60–89
Mildly decreased
G3a
45–59
Mildly–moderately decreased
G3b
30–44
Moderately–severely decreased
G4
15–29
Severely decreased
G5
<15
Kidney failure
Formula — CKD-EPI 2021 (race-free)
Female, Scr ≤ 0.7: eGFR = 142 × (Scr/0.7)-0.241 × 0.9938Age × 1.012
Female, Scr > 0.7: eGFR = 142 × (Scr/0.7)-1.200 × 0.9938Age × 1.012
Male, Scr ≤ 0.9: eGFR = 142 × (Scr/0.9)-0.302 × 0.9938Age
Male, Scr > 0.9: eGFR = 142 × (Scr/0.9)-1.200 × 0.9938Age
Scr = serum creatinine in mg/dL. Result is expressed per 1.73m² body surface area and does not require a race coefficient (2021 refit, recommended by KDIGO/NKF-ASN).
About the eGFR
Estimated glomerular filtration rate (eGFR) approximates how well the kidneys filter blood, calculated from serum creatinine adjusted for age and sex. The CKD-EPI 2021 creatinine equation is the current KDIGO/NKF-ASN-recommended formula and removed the race coefficient used in earlier versions, giving a single equation for all adults.
Clinical significance
- eGFR is the primary measure used to stage chronic kidney disease (CKD) and, combined with ACR, to assign overall CKD risk (KDIGO heat map)
- A sustained eGFR <60 mL/min/1.73m² for >3 months meets one criterion for a CKD diagnosis
- Rate of decline over time is often more clinically meaningful than any single value
- eGFR is used to guide drug dosing, contrast media decisions, and nephrology referral timing (typically at G4–G5 or rapid decline)
Limitations & causes of inaccuracy
- Not validated for age <18, pregnancy, or acute kidney injury (creatinine must be at steady state)
- Less accurate at extremes of muscle mass or body size (amputees, bodybuilders, malnutrition, sarcopenia)
- High protein intake, cooked meat consumption, and vigorous exercise can transiently raise creatinine
- Certain drugs (e.g. trimethoprim, cimetidine) block creatinine tubular secretion without affecting true GFR
- Cystatin C-based or combined creatinine-cystatin C equations are preferred when creatinine-based estimates are unreliable
Best practice
- Confirm an abnormal eGFR on a repeat sample, ideally with a urine ACR, before diagnosing CKD
- Ensure the creatinine assay is IDMS-traceable, as required by the CKD-EPI equation
- Interpret alongside clinical context: hydration status, recent illness, medications, and trend over time
