eGFR Calculator
Calculate your estimated glomerular filtration rate (eGFR) using the race-free CKD-EPI 2021 equation. Assess kidney function and CKD stage from age, gender, and serum creatinine.
About This Calculator
The eGFR (estimated Glomerular Filtration Rate) calculator estimates how efficiently your kidneys filter waste from your blood. It uses the race-free CKD-EPI 2021 creatinine equation — the current international standard recommended by the National Kidney Foundation and the American Society of Nephrology. This calculator is intended for adults aged 18 and above and is designed for both patients and healthcare professionals.
The CKD-EPI 2021 equation calculates eGFR as 142 × min(SCr/κ, 1)^α × max(SCr/κ, 1)^(-1.200) × 0.9938^Age × (1.012 if female), where SCr is serum creatinine in mg/dL, κ is 0.7 for females or 0.9 for males, and α is -0.241 for females or -0.302 for males. Results are expressed in mL/min/1.73m² and classified into CKD stages G1 through G5. This formula was updated in 2021 to remove race as a variable, making it equitable across all populations.
Regional Notes
India: The CKD-EPI 2021 equation is recommended by the Indian Society of Nephrology. Serum creatinine is commonly reported in mg/dL. The prevalence of CKD in India is estimated at 17.2%, with diabetes and hypertension as leading causes. Many Indian laboratories now use IDMS-standardized creatinine assays, which this equation requires for accuracy.
US: The National Kidney Foundation recommends annual eGFR screening for adults with diabetes, hypertension, or family history of kidney disease. Most US laboratories automatically report eGFR alongside creatinine using the CKD-EPI equation. Medicare covers annual kidney function testing for at-risk individuals.
UK: NICE guidelines recommend CKD-EPI eGFR reporting with all serum creatinine requests in adults. UK laboratories report eGFR in mL/min/1.73m² with CKD stage. The NHS Health Check includes kidney function testing for adults aged 40-74.
Frequently Asked Questions
What is eGFR and how is it calculated?
eGFR (estimated Glomerular Filtration Rate) estimates how well your kidneys filter blood. This calculator uses the race-free CKD-EPI 2021 creatinine equation: eGFR = 142 × min(SCr/κ, 1)^α × max(SCr/κ, 1)^(-1.200) × 0.9938^Age × F, where κ, α, and F differ for males and females. It uses your age, gender, and serum creatinine level to estimate kidney function in mL/min/1.73m².
What is a normal eGFR range?
A normal eGFR is 90 mL/min/1.73m² or above, which is classified as CKD Stage G1. Values between 60-89 indicate mildly reduced function (Stage G2). eGFR naturally declines with age — a value above 60 is generally considered normal for older adults. Values below 60 for three months or more indicate chronic kidney disease (CKD).
How accurate is the CKD-EPI 2021 equation?
The CKD-EPI 2021 creatinine equation is the current gold standard recommended by the National Kidney Foundation and the American Society of Nephrology. It was updated in 2021 to remove race as a variable, making it more equitable. The equation has been validated in large multinational studies and is accurate for most adults. However, eGFR remains an estimate — measured GFR (mGFR) using exogenous filtration markers is more precise but not routinely performed.
How do I interpret my CKD stage?
CKD staging ranges from G1 to G5. Stage G1 (eGFR ≥ 90) indicates normal kidney function. Stage G2 (60-89) mildly decreased. Stage G3a (45-59) mildly to moderately decreased. Stage G3b (30-44) moderately to severely decreased. Stage G4 (15-29) severely decreased. Stage G5 (< 15) indicates kidney failure. Your stage helps guide monitoring frequency, medication adjustments, and specialist referral. These thresholds are the same worldwide.
What factors can affect eGFR results?
Several factors can affect eGFR accuracy: recent high-protein meals, extreme muscle mass or amputation, pregnancy, certain medications (trimethoprim, cimetidine), acute kidney injury, and non-standardized creatinine assays. eGFR is most reliable when calculated from a steady-state creatinine. Always confirm abnormal results with repeat testing and discuss with your healthcare provider.
How does the NHS or health systems in the UK and US use eGFR?
In the US, the National Kidney Foundation recommends annual eGFR screening for adults with diabetes, hypertension, or family history of kidney disease. In the UK, NICE guidelines recommend eGFR testing for the same risk groups and automatically report eGFR alongside creatinine. Both systems use the CKD-EPI equation and classify CKD using the same G1-G5 staging system. The threshold for CKD diagnosis (eGFR < 60 for ≥ 3 months) is uniform internationally.
Is an eGFR of 60 or above always normal?
Not necessarily. An eGFR of 60 or above without other markers of kidney damage is generally considered normal. However, eGFR naturally declines with age at about 1 mL/min/1.73m² per year after age 40. A young adult with eGFR of 65 may have underlying kidney disease, while the same value in an 80-year-old may be age-appropriate. Always consider eGFR alongside urine albumin-to-creatinine ratio (uACR) for complete kidney health assessment.
Can I use this calculator if I am from India, the UK, or the US?
Yes, the CKD-EPI 2021 equation is validated for use worldwide. It was developed using data from multi-ethnic populations including North American, European, Chinese, and African cohorts. The race-free formula applies equally to all populations. Serum creatinine reference ranges may vary slightly between laboratories, but the equation itself is universal. Your healthcare provider can interpret results based on local reference ranges.