GFR Calculator
Estimate glomerular filtration rate — a key measure of kidney function — from serum creatinine, age, and sex using the race-free CKD-EPI 2021 equation. Informational only; interpret lab results with your clinician.
Inputs explained
- Serum creatinine — Your blood creatinine level in mg/dL, from a lab report.
- Age — Age in years (18+; the equation is validated for adults).
- Sex — The equation uses different constants for male and female.
How to use it
- Fill in the fields above — each input has a hint describing exactly what to enter
- Press Calculate to get your result instantly, right on this page
- Copy the result, save the tool to favorites, or share and embed it anywhere
Understanding the result
Example: A 55-year-old woman with creatinine of 1.1 mg/dL has an estimated GFR of about 59.3 mL/min/1.73m² (stage G3a borderline).
Frequently asked questions
Why does this calculator ask for sex but not race, when older GFR formulas used race? It uses the 2021 CKD-EPI equation, which removed the race coefficient present in earlier versions after research found the race adjustment wasn't scientifically justified and could disadvantage Black patients in care decisions.
What does a GFR result mean for kidney health? GFR estimates are grouped into stages (for example, around 60-89 mL/min/1.73m² is stage G2, and below 60 signals reduced kidney function), but a single estimate is informational only and should be interpreted by a clinician alongside other tests.
Is the GFR Calculator free to use? Yes — it is completely free, with no sign-up, no download and no usage limits. You can use it as often as you need.
Is my data private? Yes. The calculation runs entirely in your browser — the values you enter are never sent to our servers, stored or shared with anyone.
What information do I need? Just the following: Serum creatinine, Age, Sex. Each field includes a hint explaining exactly what to enter.
Can I use it on my phone? Yes — the tool is fully responsive and works on any device, and the same calculator is available in the EasyWorkCalcs mobile app.
Privacy
Everything you enter into the GFR Calculator is processed entirely in your browser. Nothing is uploaded, stored or shared — your data stays on your device.