GFR Calculator

How the CKD-EPI GFR formula works

The CKD-EPI 2009 equation estimates filtration using serum creatinine, age, and sex. It compares creatinine to a sex-specific constant, applies an exponent for higher values, and then adjusts for age. When race is selected as Black, the equation includes the historical 1.159 factor used in many lab reports.

• Creatinine normalization: We divide creatinine by a constant (0.7 for women, 0.9 for men).
• Age adjustment: The equation multiplies by 0.993 raised to your age.
• Optional race factor: The Black coefficient is applied only when selected.

GFR stage interpretation

GFR staging is based on KDIGO categories. A value above 90 is considered normal if no other markers of kidney damage are present. Results between 60–89 indicate mildly reduced filtration, and values below 60 may signal chronic kidney disease when persistent. Stage alone doesn't confirm diagnosis—lab context matters.

Unit conversion notes

Many labs outside the U.S. report creatinine in µmol/L. We convert µmol/L to mg/dL by dividing by 88.4 before applying CKD-EPI. This keeps results consistent regardless of the unit you select.

Important limitations

eGFR is designed for adults with stable kidney function. It may be less accurate for people who are pregnant, have very high or very low muscle mass, or are experiencing acute kidney injury. Always interpret results with a clinician who can review your full lab panel.