GFR Calculator

How the 2021 CKD-EPI equation works

This calculator uses the 2021 CKD-EPI creatinine equation for adults. It estimates filtration using standardized serum creatinine, age, and sex. The equation does not use race.

• Creatinine normalization: We divide creatinine by a constant (0.7 for women, 0.9 for men).
• Age adjustment: The equation multiplies by 0.9938 raised to your age.
• Race-free calculation: No race coefficient is collected or applied.

GFR stage interpretation

GFR categories follow KDIGO guidance. G1 and G2 do not establish chronic kidney disease without other evidence of kidney damage. Chronicity generally requires findings lasting at least three months. A single calculator result cannot confirm a diagnosis.

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.

When to discuss your result with a professional

eGFR is designed for adults with stable kidney function. Creatinine may be a less reliable marker during pregnancy, acute kidney injury, major changes in muscle mass, amputation, bodybuilding, or some diets and medicines. Near important clinical decisions, combined creatinine-cystatin C testing is more accurate. Discuss results with a qualified healthcare professional.

Formula and clinical references

This calculator uses the adult formula published by the U.S. National Institute of Diabetes and Digestive and Kidney Diseases. Interpretation language follows the KDIGO 2024 CKD guideline.