● Clinical health

Know your kidney function in seconds.

eGFR estimates how well your kidneys are filtering blood using the CKD-EPI 2021 race-free equation — just enter your serum creatinine, age and sex.

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eGFR — Estimated Glomerular Filtration Rate

Kidney function from creatinine, age & sex — CKD-EPI 2021

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Your data

Creatinine units

Serum creatinine

mg/dL

Age — years (18–110)

Sex — as used in CKD-EPI equation

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Your result

— mL/min/1.73m²

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Enter your values above

CKD Stage—

eGFR mL/min/1.73m²—

Kidney function—

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How it's calculated

CKD-EPI 2021 — the race-free creatinine equation

The eGFR (estimated Glomerular Filtration Rate) calculator uses the CKD-EPI Creatinine 2021 equation, endorsed by KDIGO guidelines. For a 45-year-old male with serum creatinine 1.0 mg/dL, eGFR ≈ 90 mL/min/1.73m² (G1, normal). For a 65-year-old female with creatinine 1.4 mg/dL, eGFR ≈ 47 mL/min/1.73m² (G3a, mildly to moderately decreased).

The CKD-EPI 2021 equation replaced earlier versions to remove race as a variable, following recommendations from the NKF-ASN Task Force. It uses serum creatinine relative to sex-specific thresholds (kappa) to estimate kidney function without systematic bias across racial groups.

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × Sex factor
Male: κ=0.9, α=−0.302, Sex factor=1 | Female: κ=0.7, α=−0.241, Sex factor=1.012

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Convert creatinine to mg/dL if entered in µmol/L
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2
Compute Scr/κ ratio and determine which branch of the equation applies
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3
Apply CKD-EPI 2021 power terms and age factor
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4
Map eGFR to CKD stage
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Understand the terms

eGFR (estimated Glomerular Filtration Rate): A calculated estimate of how much blood the kidney nephrons filter per minute, normalized to a standard body surface area of 1.73 m². The primary marker for CKD diagnosis and staging.
Serum creatinine: A waste product of muscle creatine metabolism. Healthy kidneys continuously clear it from the blood; elevated levels suggest reduced filtration capacity.
CKD (Chronic Kidney Disease): Long-term loss of kidney function, classified in five stages (G1–G5) based on eGFR and other markers such as urine albumin. G5 represents kidney failure.
Glomerular filtration: The process by which the glomeruli (tiny capillary clusters in each nephron) filter small molecules and waste from the blood into the kidney tubules.
Nephron: The functional unit of the kidney. Each kidney contains about one million nephrons; CKD progressively reduces the number of functioning nephrons.

See the full glossary →

Disclaimer: estimation tool for informational and planning purposes, using the CKD-EPI 2021 creatinine equation (reference year 2021). The actual eGFR may differ depending on laboratory method, measurement conditions and individual factors. A single eGFR value does not diagnose CKD — KDIGO recommends confirming with a second measurement ≥90 days apart. This tool does not replace assessment by a physician or nephrologist.

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Frequently asked questions — eGFR

What is eGFR and why does it matter?

eGFR (estimated Glomerular Filtration Rate) measures how well your kidneys filter waste from the blood, in mL/min/1.73 m². It is the primary marker used to diagnose and stage Chronic Kidney Disease (CKD). A value of 90 or above is generally normal; values below 15 indicate kidney failure requiring dialysis or transplant.

What equation does this calculator use?

This calculator uses the CKD-EPI Creatinine 2021 equation, which is race-free and recommended by KDIGO 2024 guidelines. It takes serum creatinine, age and sex as inputs. The formula applies different power-law coefficients depending on whether creatinine is above or below a sex-specific kappa threshold (0.9 for males, 0.7 for females).

What are the CKD stages based on eGFR?

G1: eGFR ≥ 90 (normal or high). G2: 60–89 (mildly decreased). G3a: 45–59 (mild to moderately decreased). G3b: 30–44 (moderately to severely decreased). G4: 15–29 (severely decreased). G5: below 15 (kidney failure). These stages are defined by KDIGO guidelines and are used worldwide to guide treatment decisions.

What is serum creatinine and how do I get it?

Serum creatinine is a waste product of muscle metabolism that healthy kidneys continuously filter out. It is measured from a routine blood test ordered by a physician. Levels vary with muscle mass, diet and hydration, which is why the CKD-EPI formula also uses age and sex to convert it into an eGFR estimate.

Can eGFR confirm kidney disease on its own?

A single eGFR value is not sufficient to confirm CKD. KDIGO guidelines require two eGFR measurements at least 90 days apart, and may also consider the urine albumin-to-creatinine ratio (UACR) and other markers. Always discuss any abnormal result with a nephrologist or primary care physician.

📚 Learn more — official sources

🔬 Study Inker et al. (2021) — New CKD-EPI Creatinine Equation (NEJM) Original publication of the 2021 race-free CKD-EPI creatinine equation in the New England Journal of Medicine, validated in a large multi-ethnic cohort. Read on NEJM → 📋 Guideline KDIGO 2024 CKD Guidelines — Evaluation and Management International clinical practice guidelines from KDIGO (Kidney Disease: Improving Global Outcomes) defining CKD stages and recommending eGFR as the primary diagnostic marker. See KDIGO guidelines → 🏛️ Organization National Kidney Foundation — eGFR & CKD Stages NKF patient and clinician resource explaining eGFR, CKD stages, what the numbers mean and next steps when a result is abnormal. See official source → 🏛️ Organization NIDDK — Chronic Kidney Disease (CKD) National Institute of Diabetes and Digestive and Kidney Diseases overview of CKD causes, risk factors, diagnosis (including eGFR) and management options. See official source →

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About the eGFR Calculator

The eGFR (estimated Glomerular Filtration Rate) is the primary measure of kidney function used worldwide. This calculator implements the CKD-EPI Creatinine 2021 equation — the race-free formula published by Inker et al. in the New England Journal of Medicine and endorsed by KDIGO 2024 guidelines. It uses serum creatinine, age and sex to estimate filtration rate without systematic bias across racial groups.

Results are mapped to the six KDIGO CKD stages (G1–G5), shown on a visual gauge with color-coded zones from normal (green) to kidney failure (dark red). A single eGFR value should always be interpreted by a physician; KDIGO requires two measurements at least 90 days apart to confirm CKD. For a fuller picture, pair eGFR with the urine albumin-to-creatinine ratio (UACR).