GFR Calculator

Estimated Glomerular Filtration Rate (eGFR) is a commonly used metric to assess how well the kidneys are filtering waste products from the blood. It is derived from the serum creatinine concentration together with patient age, sex and other factors. Modern equations such as CKD-EPI (recent updates) provide estimates intended to be broadly applicable across populations.

This calculator uses accepted clinical formulas to provide an estimated eGFR value. Keep in mind that eGFR is a screening and monitoring tool — definitive clinical interpretation should be made by a healthcare professional who can consider symptoms, laboratory trends, medications and comorbidities that may affect kidney function.

Interpreting eGFR Values

Values are typically grouped into stages that describe the degree of kidney function. For example, values of 90 and above are considered normal, while values below 60 may indicate chronic kidney disease when persistent. Lower values indicate greater loss of filtering capacity and may require specialist care.

Factors That Influence eGFR

• Hydration status — dehydration can increase serum creatinine and lower eGFR.
• Medications — some drugs impact creatinine secretion or kidney function.
• Acute illness — acute kidney injury can cause rapid changes in eGFR that require immediate attention.
• Muscle mass — creatinine is produced by muscle; very low or very high muscle mass can skew results.

What To Do With Your Result

If your estimated eGFR is below the expected range, consider repeating the lab test, review medications with your clinician, and assess for reversible causes such as dehydration. Persistent reductions should prompt clinical follow-up and possible referral to a nephrologist for staging, monitoring and management.

Use this tool as an informative guide rather than a diagnostic determination. Combining eGFR with urine tests, imaging and clinical assessment gives a complete picture of kidney health.