eGFR Kidney Function Calculator | kidney disease calculator

Enter Your Lab Values

Serum Creatinine

mg/dL

From a recent blood test (fasting not required)

Age (years)

yrs

CKD-EPI 2021 is validated for adults 18+

Gender

The equation uses gender-specific coefficients (no race variable, per 2021 update)

—

Where Your eGFR Falls

eGFR

G5G4G3bG3aG1-G2

G1-G2

60+

G3a

45-59

G3b

30-44

15-29

<15

✓

Medically reviewed against the CKD-EPI 2021 race-free equation (Inker et al., NEJM 2021), recommended by the National Kidney Foundation. Last checked: July 2026.

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CKD Stages Reference (NKF / KDIGO)

Stage	eGFR (mL/min/1.73m²)	Description
G1	90 or higher	Normal kidney function (CKD only if other damage markers present)
G2	60–89	Mildly decreased (CKD only if other damage markers present)
G3a	45–59	Mild to moderate decrease
G3b	30–44	Moderate to severe decrease
G4	15–29	Severely decreased kidney function
G5	Below 15	Kidney failure — may require dialysis or transplant evaluation

Stages G1 and G2 only count as CKD if other markers of kidney damage (such as protein in the urine) are also present for 3+ months. eGFR alone below 60 for 3+ months is used to define stages G3-G5.

What Is eGFR?

eGFR (estimated glomerular filtration rate) is a calculated estimate of how well your kidneys filter waste and excess fluid from your blood, expressed in milliliters per minute per 1.73 square meters of body surface area. It's calculated from a routine blood test measuring serum creatinine, combined with your age and gender, and is the primary screening and staging test for chronic kidney disease (CKD) used by doctors worldwide.

This calculator uses the CKD-EPI 2021 equation, the current standard recommended by the National Kidney Foundation and American Society of Nephrology (NKF-ASN) Joint Task Force. This 2021 update removed a race coefficient that was part of earlier versions of the equation (used from 1999 through 2020), following a comprehensive review that found the race-based adjustment was not well justified and could contribute to disparities in kidney care, particularly for Black patients.

The CKD-EPI 2021 Formula

The equation is: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.200 × 0.9938^age × 1.012 (if female), where Scr is standardized serum creatinine in mg/dL, κ (kappa) is 0.7 for women or 0.9 for men, and α (alpha) is -0.241 for women or -0.302 for men. The equation's piecewise structure reflects the non-linear relationship between creatinine and true GFR — at low creatinine levels, small changes have a larger relative effect on estimated kidney function than at high creatinine levels.

Why the Race-Free Update Matters

For over two decades, standard eGFR equations included a coefficient that produced higher (seemingly better) eGFR values for patients identified as Black, based on population data suggesting higher average creatinine levels. In 2020, the NKF-ASN Task Force reviewed this practice and concluded it wasn't adequately justified biologically and could delay diagnosis, specialist referral, and transplant eligibility for Black patients. The CKD-EPI 2021 equation used in this calculator removes that variable entirely, providing the same formula for everyone regardless of race — now the standard across US labs and increasingly adopted in UK and international settings as well.

Why a Single Reading Isn't a Diagnosis

Chronic kidney disease is formally defined by reduced eGFR (or other markers of kidney damage) persisting for at least 3 months. Creatinine — and therefore calculated eGFR — can shift temporarily due to dehydration, a recent high-protein meal, intense exercise, certain medications, or acute illness. This is exactly why a single low reading should prompt repeat testing and clinical evaluation rather than immediate alarm, and why doctors interpret eGFR trends over time rather than any one isolated result.

Factors That Can Affect Accuracy

Muscle mass — creatinine comes from muscle breakdown, so very high or very low muscle mass (bodybuilders, amputees, older adults with muscle loss) can skew results
Diet — a recent large meat meal can temporarily raise creatinine
Hydration status — dehydration can artificially lower calculated eGFR
Certain medications — some drugs affect creatinine measurement or kidney filtration temporarily without reflecting true long-term kidney damage
Pregnancy — this equation is not validated for use during pregnancy

Common Causes of Reduced Kidney Function

Diabetes — the leading cause of chronic kidney disease worldwide
High blood pressure — the second most common cause, creating a damaging cycle since CKD can also raise blood pressure
Glomerulonephritis and other kidney-specific conditions — inflammation or damage to the kidney's filtering units
Family history and genetic conditions — such as polycystic kidney disease
Long-term use of certain medications — including some over-the-counter pain relievers when used excessively over years

Given the strong links between kidney function, blood pressure, and blood sugar, this is exactly why nephrology guidelines recommend evaluating these markers together rather than in isolation.

⚕️ Medical Disclaimer: This tool provides estimates for informational purposes only and is not a substitute for professional medical advice or diagnosis. A single eGFR result cannot diagnose chronic kidney disease. Always discuss your lab results with a qualified healthcare provider.

Frequently Asked Questions

eGFR (estimated glomerular filtration rate) is a calculated estimate of how well your kidneys are filtering waste from your blood, expressed in mL/min/1.73m2. It is calculated from serum creatinine, age, and gender, and is the primary test used to detect and stage chronic kidney disease.

This calculator uses the CKD-EPI 2021 creatinine equation, the current race-free formula recommended by the National Kidney Foundation and American Society of Nephrology Task Force, which replaced earlier equations that included a race coefficient.

An eGFR of 90 mL/min/1.73m2 or higher is generally considered normal kidney function, though it naturally declines somewhat with age. An eGFR consistently below 60 for more than 3 months is used to help define chronic kidney disease.

No. Chronic kidney disease is generally defined by reduced eGFR or other markers of kidney damage persisting for at least 3 months, so a single low reading is not enough for diagnosis on its own and should be confirmed with repeat testing and clinical evaluation.

Dehydration, very high or very low muscle mass, a recent high-protein meal, certain medications, and acute illness can all temporarily affect creatinine levels and therefore eGFR, which is why single readings are interpreted cautiously and often repeated.

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