eGFR Calculator

Estimate your kidney function using the 2021 CKD-EPI race-free equation. eGFR is the primary measure used to detect, stage, and monitor chronic kidney disease (CKD).

This calculator uses the 2021 CKD-EPI equation, which removed the race coefficient to improve equity and accuracy across all populations.

eGFR = 142 × min(Cr/κ, 1)α × max(Cr/κ, 1)-1.200 × 0.9938Age × Ssex

Important: eGFR is an estimate — confirm with your physician. Do not change medications or treatments based on this result alone. A single eGFR value does not diagnose CKD; diagnosis requires two measurements at least 90 days apart.

CKD Staging Reference

≥ 90G1 — Stage 1Normal or high
60 – 89G2 — Stage 2Mildly decreased
45 – 59G3a — Stage 3aMild–moderate decrease
30 – 44G3b — Stage 3bModerate–severe decrease
15 – 29G4 — Stage 4Severely decreased
< 15G5 — Stage 5Kidney failure

Units: mL/min/1.73m². Source: KDIGO 2012 Clinical Practice Guideline.

What Is eGFR and Why It Matters

The estimated glomerular filtration rate (eGFR) measures how well your kidneys filter waste from your blood. Your kidneys contain roughly one million tiny filters called glomeruli. eGFR estimates how many milliliters of blood they clean per minute, adjusted for body surface area (1.73 m²).

Why it matters: CKD affects approximately 1 in 7 adults in the United States and is often completely asymptomatic until late stages. eGFR is the most sensitive routine marker for detecting kidney function decline early, when lifestyle and medical interventions have the greatest impact.

The 2021 CKD-EPI update: The original CKD-EPI equation included a race coefficient that assigned higher eGFR values to Black patients, which led to delayed referrals and treatment. The 2021 race-free equation was validated in over 1.2 million individuals and is now recommended by the National Kidney Foundation and American Society of Nephrology.

Creatinine vs cystatin C: eGFR based on serum creatinine (used here) can be affected by muscle mass — athletes and very muscular individuals may have higher creatinine without worse kidney function. If your eGFR is borderline, your doctor may order cystatin C, which is less influenced by muscle mass.

When to See a Nephrologist

The National Kidney Foundation recommends nephrology referral when:

  • eGFR falls below 30 mL/min/1.73m² (Stage 4)
  • eGFR drops more than 5 mL/min/1.73m² per year
  • Urine albumin-to-creatinine ratio (UACR) is above 300 mg/g
  • The cause of CKD is unclear or there is a suspicion of glomerulonephritis
  • Blood pressure is difficult to control despite multiple medications
  • You have Stage 3 CKD with additional complications (anemia, mineral/bone disorder)

Even if your eGFR is in Stage 1 or 2, it's important to identify and treat the underlying cause (diabetes, hypertension, autoimmune disease) to slow progression.

Frequently Asked Questions

What does eGFR mean?
Estimated Glomerular Filtration Rate measures how well your kidneys filter waste from your blood. Normal is above 90 mL/min/1.73m². It is calculated from serum creatinine, age, and sex.
Can eGFR be temporarily low?
Yes. Dehydration, high-protein meals before the test, intense exercise, and medications like NSAIDs or ACE inhibitors can all temporarily lower eGFR without indicating kidney disease.
What is the 2021 CKD-EPI equation?
The updated formula that removed the race coefficient, providing more equitable kidney function estimates. This calculator uses the race-free version, which is now the clinical standard.
When should I see a nephrologist?
If eGFR is persistently below 60 on two tests taken 3 months apart, if you have protein in your urine, or if eGFR is declining rapidly (more than 5 mL/min/year).
Does creatine supplementation affect eGFR?
Yes. Creatine supplements raise serum creatinine and can falsely lower calculated eGFR by 5-15 points. Tell your doctor if you take creatine so they can interpret results correctly.

Track your kidney labs over time with Vitalix

Upload your creatinine results to Vitalix and track your eGFR trend alongside blood pressure, medications, and other biomarkers. AI flags meaningful changes and recommends next steps.

Start Tracking Free

This calculator is for informational purposes only and does not constitute medical advice. eGFR is an estimate — confirm with your physician. Do not change medications based on this result. Always consult a qualified healthcare provider for interpretation of lab results and treatment decisions.