GFR Calculator – Estimate Glomerular Filtration Rate
Estimate your glomerular filtration rate (kidney function) from a blood creatinine test.
About the GFR Calculator
What is the GFR Calculator?
A GFR calculator estimates kidney function using your age, sex and blood creatinine, following the MDRD equation.
Why use this calculator?
Your GFR is the single best overall gauge of how well your kidneys filter waste. Doctors use it to stage chronic kidney disease and decide on follow-up.
How to use it
- Enter your age and select your sex.
- Enter the serum creatinine from your blood test (mg/dL).
- Select whether you have African American ancestry.
- Read your eGFR and its stage.
Formula
eGFR = 175 × creatinine^−1.154 × age^−0.203 × sex × race factors.
This is a screening estimate, not a diagnosis. Confirm results — including race and other markers — with your clinician.
Frequently Asked Questions
What is a normal GFR?
Typically 90 or above in young adults, decreasing slowly with age. Values below 60 for three months suggest chronic kidney disease.
What raises creatinine?
High muscle mass, heavy workouts, dehydration and some medications. That is why GFR uses age and sex to interpret creatinine.
Is this a medical diagnosis?
No. This tool provides general wellness information only. It is not a substitute for evaluation by a qualified healthcare professional.
Why do results differ from my doctor's measurements?
Clinical measurements use calibrated equipment and professional technique. Home estimates rely on formulas and self-reported values, so small differences are normal.
How often should I recalculate?
Recheck after meaningful changes such as weight gain or loss, a new workout routine, or every few months to track trends over time.
Do these formulas apply to everyone?
Most population formulas are less accurate for athletes, pregnant people, very young children and the elderly. Use them as a general guide.
Is this calculator free to use?
Yes. Every calculator on this site is completely free, with no hidden fees, no subscriptions and no limits on how many times you can use it.
How accurate are the results?
We use standard, widely accepted formulas and calculate in your browser using double-precision arithmetic. Results are rounded for readability, so treat them as reliable estimates rather than a guarantee. Real-world factors can vary the true figure.
Can I add this calculator to my own website?
Yes. Open this calculator page and use the "Add to your website" box in the sidebar to copy a ready-made iframe snippet, then paste it into any HTML page.
Does it work on a phone or tablet?
Yes. The layout is fully responsive, so it works on desktops, laptops, tablets and mobile phones, and every input adapts to touch screens.