eGFR Calculator — CKD-EPI 2021 (Glomerular Filtration Rate)

eGFR stands for estimated glomerular filtration rate. It estimates how many milliliters of blood your kidneys filter per minute, adjusted to a standard body surface area of 1.73 square meters (mL/min/1.73m²). This calculator uses the race-free CKD-EPI 2021 creatinine equation with your age, sex, and serum creatinine. It is an estimate, not a directly measured GFR, and it is not medical advice.

The 2021 CKD-EPI creatinine equation (Inker et al., New England Journal of Medicine 2021) is: eGFR = 142 × min(SCr/κ,1)^α × max(SCr/κ,1)^−1.200 × 0.9938^age × 1.012 if female, where κ is 0.7 for women and 0.9 for men, α is −0.241 for women and −0.302 for men, and SCr is serum creatinine in mg/dL. The 2021 version removed the race coefficient used in older equations.

Divide the µmol/L value by 88.4. For example, 88.4 µmol/L equals 1.0 mg/dL. This calculator performs the conversion automatically when you select µmol/L as the unit.

KDIGO groups eGFR into G categories: G1 (≥90, normal or high), G2 (60–89, mildly decreased), G3a (45–59, mildly to moderately decreased), G3b (30–44, moderately to severely decreased), G4 (15–29, severely decreased), and G5 (below 15, kidney failure). A G category alone is not a CKD stage — staging also needs albuminuria and persistence over 3 months.

Not necessarily. KDIGO defines chronic kidney disease by cause, GFR category, and albuminuria category together, plus persistence for more than 3 months. An eGFR in G1 or G2 without markers of kidney damage is not CKD. Only a clinician with your full history and repeat laboratory tests can diagnose CKD — talk to your doctor or a nephrologist.

CKD-EPI 2021 is the current standard recommended by the National Kidney Foundation for estimating GFR and CKD screening; it is the most accurate of the three at higher GFR values. MDRD is an older equation still shown on some lab reports — it tends to underestimate at eGFR above 60, so a small difference from this calculator is expected. Cockcroft-Gault estimates creatinine clearance in mL/min (not adjusted to 1.73 m²) and needs body weight; drug labels use it for dosing, so it answers a different question.

The 2021 CKD-EPI equation was developed without a race coefficient. The older 2009 equation included one, but it was found to overestimate GFR in Black patients. The National Kidney Foundation now recommends the race-free 2021 equations for reporting eGFR.

No. Most drug dosing guidelines and FDA labels are based on creatinine clearance from the Cockcroft-Gault equation, expressed in mL/min, which is not the same as eGFR (mL/min/1.73m²). Never start, stop, or change a medication dose based on this calculator. For creatinine clearance, use a Cockcroft-Gault calculator and always confirm dosing with a clinician or pharmacist.

The equation is less precise at high GFR values, where tiny differences in creatinine produce large swings in eGFR. Many laboratories therefore report values above 90 as ≥90 rather than a specific number. This calculator shows the exact computed value for transparency, but treat high values as approximate.

Common referral triggers include eGFR below 30 (G4–G5), a rapid or sustained decline in eGFR, heavy albuminuria, or CKD with difficult-to-control blood pressure or blood sugar. This tool cannot tell you whether you need a referral — if your result worries you, discuss it with your doctor promptly.