eGFR Calculator — CKD-EPI 2021 Race-Free

What this eGFR Calculator does

This English-language eGFR estimator computes your estimated glomerular filtration rate from three values — serum creatinine, age, and sex at birth — using the CKD-EPI 2021 race-free equation endorsed by the National Kidney Foundation and the American Society of Nephrology. Roughly 1 in 7 U.S. adults has chronic kidney disease, and most don't know it; a quick GFR estimate from a routine creatinine panel is often the first signal. The calculator returns your eGFR in mL/min/1.73 m², maps it to a KDIGO G1–G5 stage, and shows the guideline-recommended recheck interval for that stage. It accepts creatinine in both mg/dL (standard in U.S. labs) and µmol/L (used in most other countries), so you can paste the number directly from your lab report without manual conversion. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs. The CDC BMI page is a useful parallel for understanding how population-level screening statistics translate — imperfectly — to individual health decisions, and the same nuance applies here: eGFR is a screening estimate, not a measured GFR.

Features

CKD-EPI 2021 race-free equation. Uses the current NKF/ASN-endorsed formula, not the deprecated 2009 version that included a race coefficient. Many online glomerular filtration calculators still ship the old equation; this one doesn't.
Dual creatinine units. Enter serum creatinine in mg/dL (U.S. labs) or µmol/L (international labs). The converter handles the ~88× unit difference internally, so you can't silently swap units and get a wildly wrong GFR estimate.
KDIGO G1–G5 staging. Each result maps to a KDIGO GFR category with a plain-English label (e.g. 'Mild to moderate') and the guideline-recommended recheck interval — 12 months for G1, down to every 3 months for G4.
Cystatin C confirmation reminder. When your computed eGFR lands near a clinical decision threshold (60 or 30 mL/min/1.73 m²), the tool flags that a cystatin C-based eGFR should be used to confirm before any management change.
Full formula transparency. The exact CKD-EPI 2021 expression — including κ and α constants for each sex — is displayed alongside the result so you can verify the computation against the published equation.
Privacy-first, no account needed. All calculations run in JavaScript in your browser. No data is transmitted, stored, or logged. You can use the tool offline once the page has loaded.

How to use the eGFR Calculator

Enter three values from your lab report, pick your creatinine unit, and the result updates instantly — no form submission needed.

Select sex at birth. Choose Male or Female. The CKD-EPI 2021 equation uses different κ and α constants for each sex (κ = 0.7 female / 0.9 male), so this field directly affects the computed eGFR.
Choose your creatinine unit. Pick mg/dL if your report is from a U.S. lab, or µmol/L for an international result. If you're unsure, U.S. creatinine values are typically between 0.5 and 1.5; international values in µmol/L are roughly 88× larger.
Enter age and serum creatinine. Type your age in whole years and paste the serum creatinine value exactly as it appears on the lab report. The formula is sensitive to creatinine precision — use at least one decimal place (e.g. 1.0 or 88.4).
Read the result. The calculator shows eGFR in mL/min/1.73 m², the KDIGO stage (G1 through G5), and a recommended recheck interval. If your eGFR is flagged near a decision threshold, follow the cystatin C confirmation note.

Common use cases

Pre-appointment sanity check. Got a creatinine result from a routine metabolic panel and heading to a primary-care visit in Austin or anywhere else? Compute the GFR estimate beforehand so you can ask informed questions about what the number means for your stage.
Medication dose adjustment planning. Many drugs — metformin, NSAIDs, certain antibiotics, and contrast agents — are renally cleared and require dose adjustment or avoidance below specific eGFR thresholds. Estimating your current GFR helps you flag the conversation with your prescriber.
Tracking kidney function over time. Paste creatinine values from multiple lab draws to estimate how your GFR has changed. A sustained decline of more than 5 mL/min/1.73 m² per year is considered rapid progression under KDIGO guidelines.
Medical education and training. Medical students and NP/PA trainees can use this GFR estimator alongside the visible formula to learn KDIGO staging hands-on. Pair it with the [BMI calculator](/en/bmi-calculator/) when teaching how population-derived screening equations differ from measured gold standards.
Patient self-education between nephrology visits. Understanding your CKD stage can help you follow dietary and fluid guidance more consistently. This tool gives you context — not a clinical decision — to bring to your next nephrology appointment.

Frequently asked questions

What is a normal eGFR range?

An estimated glomerular filtration rate of 60 mL/min/1.73 m² or higher is generally considered within the normal or mildly decreased range (KDIGO G1–G2) for adults. G1 is ≥ 90, G2 is 60–89. Values below 60 sustained for three or more months indicate CKD. Age naturally lowers GFR — a value of 65 in a 75-year-old means something different than in a 35-year-old, which is why eGFR should always be interpreted alongside albuminuria (urine ACR) and clinical context, not as an isolated number.

Why does this calculator use the 2021 equation instead of the older one?

The original 2009 CKD-EPI equation included a race coefficient that systematically estimated higher GFR for Black patients, which had the effect of delaying referrals and treatment. In 2021, the National Kidney Foundation and American Society of Nephrology convened a task force that developed and endorsed a race-free equation with comparable accuracy. This tool implements only the 2021 version. If another calculator you've used gives a different result, it may still be running the deprecated 2009 formula.

Is my health data sent anywhere when I use this tool?

No. This eGFR calculator is 100% client-side. All computation happens in your browser using JavaScript. Your age, creatinine, and sex are never transmitted to any server, never logged, and never stored. You can verify this by loading the page, disconnecting from the internet, and running the calculator — it still works.

Can I use this calculator for a patient under 18?

No. The CKD-EPI equation is validated only for adults 18 and older. Pediatric kidney function should be estimated with the Schwartz (or revised Schwartz) equation, which accounts for height and uses age-appropriate creatinine reference ranges. Using this tool for children will produce a meaningless result.

My eGFR came back near 60. Should I be worried?

A single eGFR near 60 is a snapshot, not a diagnosis. CKD requires the abnormality to persist for at least three months, and the KDIGO guideline is two-dimensional — GFR category plus albuminuria category (urine albumin-to-creatinine ratio). An eGFR of 58 with a normal ACR carries a very different risk profile than the same eGFR with significant proteinuria. Near the 60 threshold, the KDIGO 2024 guideline also recommends confirming with a cystatin C-based eGFR before changing management. Talk to your provider rather than interpreting this number in isolation.

How does eGFR relate to other health calculators like BMI?

Both eGFR and BMI are population-derived screening estimates, not direct measurements. BMI was developed in the 1830s as a population statistic — not an individual diagnostic — and the CDC BMI page makes this point explicitly. eGFR shares that limitation: it estimates kidney function from a proxy marker (creatinine) rather than measuring it directly with inulin or iohexol clearance. For a fuller metabolic picture alongside kidney function, the [TDEE calculator](/en/tdee-calculator/) can help you understand energy balance, which matters in CKD nutritional planning.