Health

eGFR Calculator

Estimate your glomerular filtration rate using the CKD-EPI 2021 race-free equation. See your kidney function stage and clinical interpretation.

Quick Answer

eGFR estimates how well your kidneys filter waste from the blood. The CKD-EPI 2021 equation uses serum creatinine, age, and sex (no race variable). Normal eGFR is 90+ mL/min/1.73m². Values below 60 for 3+ months indicate chronic kidney disease. Below 15 indicates kidney failure requiring dialysis or transplant.

Serum Creatinine

mg/dL

Age

years

Sex

Your Results

Estimated GFR

91.7

mL/min/1.73m²

CKD Stage

G1 — Normal or High

eGFR Scale

G3b

G3a

01530456090120

Clinical Interpretation

Kidney function is normal. Monitor if other risk factors are present.

CKD Stages

G1Normal or High90+You

G2Mildly Decreased60-89

G3aMild to Moderate45-59

G3bModerate to Severe30-44

G4Severely Decreased15-29

G5Kidney Failure< 15

Important: This calculator provides an estimate for educational purposes only. eGFR results should be interpreted by a qualified healthcare provider in the context of your complete medical history, other lab results, and clinical presentation. Do not make medical decisions based solely on this calculator. If you have concerns about kidney function, consult a nephrologist or your primary care physician.

About This Tool

The estimated glomerular filtration rate (eGFR) is the single most important number for assessing kidney function. Your kidneys contain roughly one million tiny filters called glomeruli, which clean approximately 180 liters of blood every day. The GFR measures how much blood these filters process per minute, expressed in milliliters per minute per 1.73 square meters of body surface area (mL/min/1.73m²). A healthy young adult typically has a GFR around 120 mL/min/1.73m², though this naturally declines with age.

The CKD-EPI 2021 Equation

This calculator uses the CKD-EPI 2021 equation, which is the current standard recommended by the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN). The 2021 update is critically important because it removed the race coefficient that was present in earlier versions of the equation. The original CKD-EPI 2009 equation included a race multiplier that gave Black patients a higher eGFR for the same creatinine level, which many experts argued could delay diagnosis and treatment of kidney disease in Black patients. The 2021 version eliminates this variable entirely, relying only on serum creatinine, age, and sex to produce a more equitable estimate of kidney function across all populations.

Understanding Serum Creatinine

Serum creatinine is a waste product generated by normal muscle metabolism. Your kidneys filter creatinine from the blood and excrete it in urine. When kidney function declines, creatinine levels in the blood rise because the kidneys cannot clear it as efficiently. Normal serum creatinine ranges are typically 0.7 to 1.3 mg/dL for men and 0.6 to 1.1 mg/dL for women, though these ranges can vary by laboratory. It is important to note that creatinine levels are influenced by muscle mass, diet (particularly protein intake), and certain medications. A muscular individual may have higher creatinine without any kidney impairment, while a frail elderly patient may have apparently normal creatinine despite significant kidney disease.

CKD Stages Explained

Chronic kidney disease is classified into five stages based on eGFR. Stage G1 (eGFR 90 or above) indicates normal kidney function, though kidney damage from other markers like proteinuria may still be present. Stage G2 (eGFR 60 to 89) represents a mild decrease in function. Stage G3 is subdivided into G3a (45 to 59, mild to moderate) and G3b (30 to 44, moderate to severe). Stage G4 (eGFR 15 to 29) is severely decreased function where patients typically need specialist care and preparation for possible renal replacement therapy. Stage G5 (eGFR below 15) represents kidney failure, where dialysis or transplant becomes necessary to sustain life.

Limitations of eGFR

While eGFR is the best single-number summary of kidney function, it has important limitations. The estimate is based on serum creatinine, which can be affected by factors other than kidney function including muscle mass, diet, hydration status, and certain medications. For patients at extremes of body size, very elderly patients, pregnant women, or those with acute kidney injury, eGFR may be less accurate. In these situations, clinicians may order a 24-hour urine collection for a measured creatinine clearance, or use cystatin C-based equations as an alternative or confirmatory test. The CKD-EPI equation also includes a cystatin C version that can be used when creatinine-based estimates are unreliable.

When to See a Doctor

If your eGFR is below 60 mL/min/1.73m² on two or more occasions separated by at least 90 days, this meets the definition of chronic kidney disease and warrants medical attention. Even a single low reading should prompt follow-up testing. Symptoms of advanced kidney disease include fatigue, swelling in the legs or ankles, decreased urine output, nausea, shortness of breath, and confusion. However, early kidney disease is often completely asymptomatic, which is why regular screening with serum creatinine and eGFR is important for people with risk factors such as diabetes, hypertension, family history of kidney disease, or age over 60. Early detection allows for interventions that can slow or halt the progression of kidney disease.

Frequently Asked Questions

What is a normal eGFR level?

A normal eGFR is 90 mL/min/1.73m² or higher. However, eGFR naturally declines with age. A healthy 70-year-old may have an eGFR around 75-80, which is normal for their age. The key concern is when eGFR drops below 60, especially if it persists for three or more months, as this indicates chronic kidney disease.

Why did the CKD-EPI 2021 equation remove the race variable?

The race variable was removed because race is a social, not biological, construct. The original race coefficient was based on the observation that Black patients tended to have higher creatinine levels due to greater average muscle mass, but this generalization does not apply to all individuals. The NKF and ASN recommended removal to promote health equity and avoid potentially delaying care for Black patients whose kidney disease might be underestimated.

How is eGFR different from creatinine clearance?

eGFR is an estimate calculated from a single blood test using an equation. Creatinine clearance is measured directly by collecting all urine produced over 24 hours and comparing the creatinine in the urine to the creatinine in the blood. Creatinine clearance is more accurate in certain situations but is inconvenient and prone to collection errors. For most clinical purposes, eGFR is sufficient and preferred.

Can eGFR improve after being low?

Yes, eGFR can improve in some cases. If the decrease was caused by a reversible factor such as dehydration, medication side effects, or an acute illness, eGFR may return to normal once the cause is addressed. In chronic kidney disease, eGFR decline can be slowed or stabilized with proper treatment, including blood pressure control, blood sugar management in diabetics, and avoiding nephrotoxic medications.

How often should I check my eGFR?

For healthy adults with no risk factors, eGFR is typically checked during routine annual physicals as part of a comprehensive metabolic panel. For those with diabetes, hypertension, or known kidney disease, testing may be recommended every 3-6 months. If your eGFR is between 30-59 (stage G3), monitoring every 3-6 months is standard. Below 30, more frequent monitoring is usually necessary.

Does diet affect eGFR results?

Diet can influence serum creatinine levels, which affects eGFR calculations. A high-protein diet, especially large amounts of cooked meat, can temporarily raise creatinine levels and lower eGFR. Creatine supplements also raise creatinine. For the most accurate results, clinicians may recommend fasting or avoiding heavy protein consumption before blood work. However, these dietary effects are usually modest and temporary.

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