How to use this CKD-EPI calculator
Enter an adult age, the sex parameter used for the equation and a laboratory serum creatinine result. Choose the unit printed on the lab report: mg/dL or µmol/L. Switching units converts the entered value. The result is indexed to a body surface area of 1.73 m².
What does “eGFR CKD-EPI Cr 2021” mean?
eGFR means estimated glomerular filtration rate. CKD-EPI names the equation group; Cr means creatinine and 2021 identifies the race-free equation version. This tool uses creatinine alone, not the separate creatinine–cystatin C equation.
Equation and example
eGFR = 142 × min(Scr / κ, 1)^α × max(Scr / κ, 1)^−1.200 × 0.9938^age × F
Scr is creatinine in mg/dL. For the female parameter, κ = 0.7, α = −0.241 and F = 1.012. For the male parameter, κ = 0.9, α = −0.302 and F = 1. Convert µmol/L to mg/dL by dividing by 88.4.
Example: age 60, male parameter and creatinine 1.2 mg/dL (106.08 µmol/L) gives approximately 69 mL/min/1.73 m² with either unit selection.
Limits of an estimate
This adult equation is not a pediatric calculator. A single result does not diagnose chronic kidney disease. Duration, urine albumin and other evidence matter; G1 or G2 alone does not establish CKD. Creatinine-based estimates can be less reliable when creatinine is changing rapidly or muscle mass differs substantially. Discuss results and medication decisions with your clinician.
Reference: National Kidney Foundation CKD-EPI 2021 equation.
About the CKD-EPI 2021 eGFR Equation
The Estimated Glomerular Filtration Rate (eGFR) is the primary clinical indicator used by nephrologists to assess renal (kidney) function. It measures how well your kidneys are filtering creatinine (a waste product from muscle breakdown) out of your blood.
The National Kidney Foundation and the American Society of Nephrology formally recommend using the updated 2021 CKD-EPI equation.
The Shift to a Race-Free Clinical Standard
Importantly, the 2021 CKD-EPI equation is race-free. Previous versions of the eGFR calculation included a race multiplier for Black patients based on outdated clinical assumptions about muscle mass. This multiplier was removed to promote health equity, as it systematically overestimated kidney function in Black patients, causing harmful delays in the diagnosis and treatment of chronic kidney disease.
Understanding the Stages of CKD
The following GFR categories describe the filtration estimate. CKD assessment also uses duration, albuminuria and other findings; this table alone is not a diagnosis:
| Stage | eGFR Range | Clinical Description |
|---|---|---|
| Stage 1 (G1) | ≥ 90 | Normal or high kidney function |
| Stage 2 (G2) | 60 - 89 | Mildly decreased kidney function |
| Stage 3a (G3a) | 45 - 59 | Mild to moderately decreased kidney function |
| Stage 3b (G3b) | 30 - 44 | Moderate to severely decreased kidney function |
| Stage 4 (G4) | 15 - 29 | Severely decreased kidney function |
| Stage 5 (G5) | < 15 | Kidney failure (ESRD) |