GFR calculator
Estimated kidney function (eGFR) from creatinine, age and sex, with the CKD-EPI 2021 equation.
About this calculator
This GFR calculator estimates how well the kidneys filter blood, the estimated glomerular filtration rate (eGFR), from a blood creatinine result, age and sex.
It uses the CKD-EPI 2021 equation recommended in the US, and shows the matching stage of kidney function.
How it works
Uses the race-free CKD-EPI 2021 creatinine equation: 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.2 × 0.9938^age, × 1.012 for women, where κ and α depend on sex.
Last reviewed:
Worked example
- Sex: Female
- Age: 50 years
- Creatinine in: mg/dL
- Serum creatinine: 1
Estimated GFR: 69 mL/min/1.73 m² (G2: mildly decreased)
Common questions
What is a normal eGFR?
90 or above is normal for most adults. It falls slowly with age. A value under 60 for three months or more can be a sign of chronic kidney disease.
Where do I find my creatinine level?
On a blood test report, often as serum creatinine, in mg/dL in the US or µmol/L in many other countries. Choose the matching unit.
Can one low eGFR mean kidney disease?
Not on its own. Dehydration, a big meal of meat or intense exercise can change creatinine. Doctors repeat tests and often check urine too.
Sources and further reading
The story behind it
Where the idea came from: In 2021, US kidney experts recommended a new eGFR equation that no longer uses race, replacing earlier versions.
Older equations adjusted results for Black patients, which could delay diagnosis and treatment. The National Kidney Foundation and the American Society of Nephrology led the change to the CKD-EPI 2021 equation, now standard in US laboratories.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, not medical advice.
- Spotted a mistake? Tell us and we'll look into it.
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