GFR calculator.
Use this free gfr calculator to get fast estimates, compare scenarios, and understand the numbers with clear step-by-step context.
Use the GFR Calculator.
Results update automatically as you type. No account is required.
Enter your values
About the GFR Calculator
Glomerular Filtration Rate (GFR) measures how well your kidneys filter waste from the blood, and estimated GFR (eGFR) is the standard screening number for kidney function. This calculator uses the modern 2021 CKD-EPI creatinine equation to estimate eGFR and the matching chronic kidney disease (CKD) stage.
How it works
It applies the race-free 2021 CKD-EPI creatinine equation, which combines your serum creatinine, age, and sex to estimate filtration rate per 1.73 m² of body surface area. Higher numbers mean better kidney function; results map to CKD stages G1 (normal) through G5 (kidney failure).
Reading the chart
The band chart places your eGFR across the CKD stages so you can see where the estimate sits — but staging requires repeat testing and clinical context.
⚠ Disclaimer: This calculator provides general estimates for education only and is not medical advice. Individual needs vary with health conditions, medication, and body composition. Consult a qualified healthcare professional before making health, nutrition, or medical decisions.
FAQ
Is a single eGFR enough to diagnose CKD?
No. Diagnosis needs repeated results over at least three months plus other findings. One value can be affected by hydration, diet, and recent activity.
What raises or lowers creatinine?
Muscle mass, meat intake, hydration, and some medications affect creatinine and therefore eGFR. Your doctor interprets it alongside other tests.
What can I do for kidney health?
Manage blood pressure and blood sugar, stay hydrated, avoid unnecessary NSAIDs, and follow medical advice. Always discuss results with a clinician.