Last updated: 2026-06-29

eGFR (CKD-EPI 2021)

The estimated glomerular filtration rate (eGFR) approximates how much blood your kidneys filter each minute, normalised to a body surface area of 1.73 m². This calculator uses the CKD-EPI 2021 creatinine equation — the international, race-free standard — to estimate eGFR from a serum creatinine value, your age, and your sex, then maps the result to the chronic kidney disease (CKD) GFR categories G1 through G5.

What the 2021 update changed

The earlier 2009 CKD-EPI equation included a coefficient that raised the estimate for patients recorded as Black. In 2021 a joint task force of the National Kidney Foundation and the American Society of Nephrology recommended removing that race term, because race is a social rather than biological variable and a race-based adjustment could delay care. The equation was refit without race and validated to maintain accuracy across the population. The version used here is that 2021 refit.

The equation

With serum creatinine (Scr) in mg/dL:

$\mathrm{eGFR} = 142 \times \min\!\left(\tfrac{\mathrm{Scr}}{\kappa}, 1\right)^{\alpha} \times \max\!\left(\tfrac{\mathrm{Scr}}{\kappa}, 1\right)^{-1.200} \times 0.9938^{\,\mathrm{Age}} \times F$

Here the constant κ is 0.7 for females and 0.9 for males, α is −0.241 for females and −0.302 for males, and F is 1.012 for females (otherwise 1). The paired min and max terms automatically pick the correct branch depending on whether creatinine sits below or above κ, so the same formula covers low and high creatinine without a manual switch.

Reading the result

eGFR is reported in mL/min/1.73 m². Higher numbers mean better-preserved filtering capacity. The CKD GFR categories are:

A category on its own does not diagnose kidney disease. G1 and G2 fall in the normal-to-mild range, and chronic kidney disease is defined by a reduced eGFR sustained for at least three months or by markers of kidney damage such as albuminuria. The estimate is most meaningful read alongside those markers and the wider clinical picture.

Units: mg/dL and µmol/L

US laboratories usually report creatinine in mg/dL, while most other countries use µmol/L. You can enter either — switching the unit to µmol/L converts the value internally (dividing by about 88.4 to reach mg/dL) before the equation is applied.

When it does not apply

CKD-EPI 2021 was developed for non-pregnant adults aged 18 and over. It is unreliable in acute kidney injury, in pregnancy, and at the extremes of muscle mass, where creatinine no longer tracks filtration well. Children need a paediatric equation such as the CKiD U25 or Schwartz formula. For the Japanese population, the Japanese Society of Nephrology (JSN) equation is the local standard and gives different numbers. To estimate an absolute clearance for drug dosing, the Creatinine Clearance Calculator uses the Cockcroft-Gault formula instead.