Glomerular filtration rate (GFR) is the best overall index of kidney function and is used to stage chronic kidney disease (CKD), guide drug dosing, and time renal replacement therapy. The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation was developed in 2009 and updated in 2021 to remove the race coefficient, making it race-free and reducing racial disparities in CKD care. It uses serum creatinine, age, and sex to estimate GFR and is more accurate than the Cockcroft-Gault and MDRD equations, particularly at higher GFR values. The National Kidney Foundation now recommends the 2021 race-free CKD-EPI as the primary equation for CKD staging.