GFR Calculator
Estimated glomerular filtration rate — the standard measure of kidney function. Uses the CKD-EPI 2021 (race-free) equation.
Estimated GFR
mL / min / 1.73 m²
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CKD stage
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Description
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⚕ This is a screening estimate. Diagnosis of chronic kidney disease requires repeat testing over 3+ months and clinical context. Talk to your doctor.
What GFR measures
The glomerular filtration rate is how much fluid your kidneys filter per minute. Healthy adults filter ~120 mL/min — the equivalent of ~180 L of plasma per day. (You don't urinate that much because the tubules reabsorb most of it.)
Creatinine is a muscle breakdown product cleared by the kidneys. If kidney function drops, creatinine rises. The CKD-EPI equation back-calculates GFR from creatinine, adjusting for age and sex.
The 2021 race-free update
Until 2021, GFR equations included a race coefficient that gave Black patients ~1.16× higher estimates for the same creatinine — based on body composition assumptions that have since been challenged as harmful. The new CKD-EPI 2021 formula removed the race term. This calculator uses the new version.
CKD stages
- G1 (≥90): Normal kidney function — but with markers of damage (proteinuria) you'd still have CKD.
- G2 (60–89): Mild decrease, very common.
- G3a (45–59), G3b (30–44): Moderate decrease — many people don't have symptoms here.
- G4 (15–29): Severe. Specialist care.
- G5 (<15): Kidney failure. Dialysis or transplant territory.
Estimate — not medical advice
eGFR is an estimate, and a fragile one at the edges. It can mislead at very high or very low muscle mass, in pregnancy, in amputees, and during acute illness. Kidney function is assessed by a clinician using trends across repeated labs, never a single computed value.
This is an estimate, not medical advice, and not a diagnosis. It doesn't know your history, your medications, or your other results, and it should never be used to start, stop, or change treatment. If a number here concerns you, take it to a doctor or pharmacist rather than acting on it.