eGFR Calculator — Kidney Function & CKD Stage (CKD-EPI 2021)
What do your kidney numbers mean?
⚕️ Educational tool only. Interpret results with your healthcare provider — they have access to your full medical history, symptoms, and repeat measurements. CKD is diagnosed after 3+ months of results, not a single reading.
eGFR & CKD Stage Calculator
Enter your serum creatinine, age, and sex to estimate kidney function using the CKD-EPI 2021 (race-free) formula. Results update live as you type.
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Calculate your estimated Glomerular Filtration Rate (eGFR) from a serum creatinine lab result using the CKD-EPI 2021 equation — the current clinical standard recommended by KDIGO guidelines. EGFR is the primary measure of kidney function and the basis for Chronic Kidney Disease (CKD) staging. A single low result doesn't diagnose CKD — the diagnosis requires readings below 60 mL/min/1.73m² or evidence of kidney damage for at least 3 months. This tool provides educational context for a lab result, not a clinical diagnosis. The CKD-EPI 2021 equation is race-free, replacing the 2009 version that included a race adjustment now considered clinically inappropriate. Results from this calculator reflect current best-practice calculation methodology. This is an educational tool. Always interpret lab results with your healthcare provider who has access to your full medical history, symptoms, trends, and clinical judgment. Understanding your eGFR stage and what it implies for management — blood pressure targets, medication review, follow-up frequency — helps you have a more informed conversation with your nephrologist or primary care doctor.
- →Looking up what a creatinine lab result means in terms of kidney function stage
- →Comparing your eGFR to the age-expected value for context
- →Understanding which CKD stage corresponds to your eGFR reading
- →Seeing what clinical monitoring and management guidelines apply to each stage
- →Educational research on chronic kidney disease staging criteria
Your bloodwork shows serum creatinine of 1.4 mg/dL. You're 58 years old, male. Enter those values — result: eGFR of approximately 52 mL/min/1.73m², placing you in CKD Stage 3a (Mildly-Moderately Decreased). The age-expected value for 58 is about 86; your result is 60% of expected. The management card shows: BP target below 130/80, avoid NSAIDs, review medications, check every 6 months.
What is a normal eGFR reading?
An eGFR of 60 or above generally indicates adequate kidney function for most clinical purposes, though eGFR naturally declines with age — the expected value for a healthy 70-year-old is around 75, not 100. An eGFR above 90 (Stage 1) is considered normal. Values between 60–89 (Stage 2) represent mildly decreased function. Below 60 for 3+ months indicates CKD, which is further staged by the degree of reduction.
What causes eGFR to decrease?
The most common causes are diabetes (diabetic nephropathy) and high blood pressure (hypertensive nephropathy), which together account for over 70% of CKD cases. Other causes include glomerulonephritis, polycystic kidney disease, recurrent kidney infections, prolonged NSAID use, contrast dye from imaging procedures, and certain medications. Dehydration, high-protein meals before the blood draw, and intense exercise can temporarily lower eGFR without reflecting underlying kidney disease.
What is the difference between eGFR and creatinine?
Serum creatinine is the raw measurement — the blood concentration of creatinine, a muscle waste product filtered by the kidneys. When kidney function declines, creatinine builds up in the blood. eGFR is a calculated estimate of kidney filtration capacity that incorporates creatinine along with age and sex to produce a standardized number comparable across different patients. eGFR is more clinically useful than creatinine alone because a value of 1.4 mg/dL means very different things for a 25-year-old vs. a 75-year-old.
Can you have a normal creatinine but low eGFR, or vice versa?
Yes. Older patients and those with low muscle mass produce less creatinine, so their creatinine level may appear 'normal' (within lab reference ranges) even when kidney function is significantly reduced. The eGFR calculation adjusts for age specifically to catch this. Conversely, a muscular young person may have a creatinine slightly above the reference range while eGFR is completely normal. This is why eGFR is preferred over creatinine alone for assessing kidney function.
Should I be concerned about a single low eGFR reading?
A single result below 60 warrants follow-up testing, but CKD is only diagnosed after low readings persist for 3+ months or when there's structural evidence of kidney damage. Transient causes — dehydration, illness, certain medications, and intense exercise — can temporarily reduce eGFR. Your doctor will typically order repeat testing and may add other markers like urine albumin-to-creatinine ratio (uACR) to assess whether any reduction is persistent and clinically significant.