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eGFR Calculator

The estimated Glomerular Filtration Rate (eGFR) is a calculated estimate of how well your kidneys are filtering waste from your blood, expressed in mL/min/1.73 m². It is not a direct measurement — it is derived from serum creatinine combined with age and sex using a validated mathematical equation. The equation used here is the CKD-EPI 2021 race-free formula, the current standard recommended by the National Kidney Foundation and the American Society of Nephrology. eGFR is the primary metric used to stage chronic kidney disease (CKD) and is one of the most clinically important numbers in metabolic health. This tool provides estimates for educational purposes only. Lab results must be interpreted by a qualified healthcare provider in the context of your full medical history.

Reviewed by GetHealthyCalculators Editorial Team · Updated April 11, 2026

Quick Answer

eGFR ≥ 90 is normal (G1), 60–89 is mildly decreased (G2), 45–59 is G3a, 30–44 is G3b, 15–29 is G4 (severe), and below 15 may suggest kidney failure (G5). Any result below 60 should be discussed with a doctor.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

From a routine blood test (serum, not urine). Normal range: approx. 0.6–1.2 mg/dL.

Biological Sex (used in the CKD-EPI formula)

Enter your serum creatinine, age, and biological sex to estimate your eGFR.

How the Formula Works

  1. Obtain a serum creatinine value (mg/dL) from a routine blood test. The sample does not need to be fasting.

  2. Determine the sex-specific constants: κ (kappa) and α (alpha).

    Female: κ = 0.7, α = −0.241 | Male: κ = 0.9, α = −0.302

  3. Calculate the ratio of serum creatinine (Scr) to κ.

    ratio = Scr / κ

  4. Apply the CKD-EPI 2021 piecewise power function.

    eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200) × 0.9938^Age × (1.012 if female)

  5. Interpret the result using CKD staging (G1–G5). A single eGFR measurement should be confirmed with a repeat test before any clinical decision is made.

Methodology & Sources

Reviewed and updated April 11, 2026 · Prepared by GetHealthyCalculators Editorial Team

This calculator implements the CKD-EPI Creatinine 2021 equation, published by Inker et al. in the New England Journal of Medicine (2021). The 2021 revision removed race as a variable compared to the 2009 equation, following recommendations from the National Kidney Foundation–American Society of Nephrology Task Force. This equation is now the standard recommended for eGFR reporting in the United States. Creatinine must be calibrated to the isotope dilution mass spectrometry (IDMS) traceable standard, which has been the laboratory standard since approximately 2011.

References

Limitations

  • eGFR is an estimate, not a direct measurement of kidney filtration rate. The true GFR requires invasive clearance studies.
  • The CKD-EPI equation was derived from specific study populations and may be less accurate at extremes of body composition, very high muscle mass (e.g., bodybuilders), or very low muscle mass (e.g., elderly, amputees).
  • A single eGFR value does not diagnose chronic kidney disease — CKD is defined by values sustained over at least 3 months.
  • Creatinine levels can fluctuate with diet (high meat intake temporarily raises creatinine), dehydration, and intense exercise.
  • This calculator uses creatinine-based eGFR only. Cystatin C-based eGFR provides a complementary estimate and may be more accurate in some populations — ask your doctor.
  • This tool is for adults aged 18 and older. Pediatric kidney function uses different equations (Schwartz formula).

Frequently Asked Questions

What is eGFR and what does it measure?
eGFR stands for estimated Glomerular Filtration Rate. It estimates how many milliliters of blood your kidneys filter per minute per 1.73 m² of body surface area. It is calculated from your serum creatinine level combined with your age and sex — it is not directly measured. A higher eGFR generally means better kidney function.
What eGFR is considered normal?
An eGFR of 90 or above is considered normal for most adults (CKD G1 stage). Values between 60 and 89 represent mild reduction (G2) and are common in older adults without kidney disease. Any value consistently below 60 may suggest chronic kidney disease and should be discussed with a doctor.
Why was race removed from the CKD-EPI 2021 equation?
The original 2009 CKD-EPI equation included a race adjustment that produced higher eGFR estimates for Black patients. The NKF-ASN Task Force concluded in 2021 that race is a social — not biological — variable and its inclusion led to delayed CKD diagnosis and referral for Black patients. The 2021 race-free equation produces equivalent estimates for all patients without using race.
Can a low eGFR be temporary?
Yes. Dehydration, high-protein meals, intense exercise, certain medications (e.g., NSAIDs, ACE inhibitors, contrast dye), and acute illness can all temporarily reduce eGFR. This is why CKD is defined by persistent values below 60 over at least 3 months, not a single test result.
At what eGFR should I see a nephrologist?
Guidelines generally recommend referral to a nephrologist when eGFR falls below 30 (G4 stage) or earlier if eGFR is declining rapidly, protein is detected in urine, or the cause of CKD is unclear. Your primary care doctor will guide the timing of referral based on your full clinical picture.
Does diet affect creatinine and eGFR?
Yes. A high-protein or high-meat diet temporarily raises serum creatinine, which lowers the calculated eGFR. Creatine supplementation can also raise creatinine. If you eat large amounts of meat or take creatine, inform your doctor — your true kidney function may be better than the eGFR estimate suggests.
Is this calculator suitable for children?
No. The CKD-EPI equation is validated for adults 18 years and older. Kidney function in children and adolescents is estimated using the Schwartz formula, which incorporates height. Consult a pediatric nephrologist for age-appropriate evaluation.

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