eGFR Calculator — Estimated Kidney Function

How it works

CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × (1.012 if female) · κ = 0.7 (female) / 0.9 (male) · α = −0.241 (female) / −0.302 (male)

The estimated glomerular filtration rate approximates how many millilitres of blood the kidneys clear of creatinine each minute, normalised to a standard 1.73 m² body surface. The 2021 CKD-EPI creatinine equation dropped the older race coefficient and is now the recommended default in the US; it uses serum creatinine, age and sex only. eGFR falls naturally with age and defines chronic-kidney-disease stages G1–G5, but a single value can be thrown off by muscle mass, diet and acute illness, so trends and confirmatory testing matter more than one reading.

Worked example

For a 55-year-old man with serum creatinine 1.0 mg/dL: κ = 0.9 so the ratio is 1.11; min(1.11,1)^−0.302 = 1, max(1.11,1)^−1.2 = 0.881, and 0.9938^55 = 0.710. eGFR = 142 × 1 × 0.881 × 0.710 ≈ 89 mL/min/1.73m² — CKD stage G2.

Sources: CKD-EPI 2021 creatinine equation (NKF)

Frequently asked questions