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.

Serum Creatinine

Switch to µmol/L if your lab reports creatinine that way.

Age

years

Sex

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

≥90

Normal or high

60–89

Mildly decreased

G3a

45–59

Mildly–moderately decreased

G3b

30–44

Moderately–severely decreased

15–29

Severely decreased

<15

Kidney failure

Formula — CKD-EPI 2021 (race-free)

Female, Scr ≤ 0.7: eGFR = 142 × (Scr/0.7)^-0.241 × 0.9938^Age × 1.012 Female, Scr > 0.7: eGFR = 142 × (Scr/0.7)^-1.200 × 0.9938^Age × 1.012 Male, Scr ≤ 0.9: eGFR = 142 × (Scr/0.9)^-0.302 × 0.9938^Age Male, Scr > 0.9: eGFR = 142 × (Scr/0.9)^-1.200 × 0.9938^Age

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