This GFR calculator estimates your glomerular filtration rate (eGFR), the main measure of how well your kidneys filter blood. It uses the CKD-EPI 2021 creatinine equation, the race-free equation recommended by the National Kidney Foundation and the American Society of Nephrology, and accepts creatinine in mg/dL or µmol/L.
The CKD-EPI 2021 equation
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938age × 1.012 [if female]
- Scr is serum creatinine in mg/dL (µmol/L ÷ 88.4).
- κ is 0.7 for females and 0.9 for males.
- α is −0.241 for females and −0.302 for males.
The result is in mL/min/1.73 m², adjusted to an average body surface area. Unlike older equations, the 2021 version does not use race.
GFR categories
| Category | eGFR (mL/min/1.73 m²) | Description |
|---|---|---|
| G1 | 90 or more | Normal or high |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mildly to moderately decreased |
| G3b | 30–44 | Moderately to severely decreased |
| G4 | 15–29 | Severely decreased |
| G5 | Under 15 | Kidney failure |
Chronic kidney disease is diagnosed when eGFR stays below 60 for at least three months, or when there are other signs of kidney damage, such as albumin in the urine, at any eGFR.
Worked example
A 50-year-old man with a serum creatinine of 1.0 mg/dL (88 µmol/L) has an eGFR of about 92 mL/min/1.73 m², category G1. A 50-year-old woman with the same creatinine has an eGFR of about 69, because women typically have less muscle and so less creatinine.
When the estimate is less reliable
- Very high or low muscle mass, such as bodybuilders or people with amputations.
- Pregnancy, and kidney function that is changing quickly (acute kidney injury).
- Large meat meals or creatine supplements before the blood test.
In these cases, doctors may use a cystatin C test or a measured GFR instead.
Frequently asked questions
What is a normal eGFR?
An eGFR of 90 or more is normal for most adults. GFR naturally declines with age, so a value in the 60s can be common in older adults without kidney disease if there are no other signs of damage.
Why was race removed from the eGFR equation?
The older CKD-EPI 2009 equation included a race coefficient. In 2021, the National Kidney Foundation and the American Society of Nephrology recommended the race-free equation used here so that results do not depend on race.
How do I convert creatinine from µmol/L to mg/dL?
Divide by 88.4. For example, 88 µmol/L is about 1.0 mg/dL. The calculator does this automatically when you choose µmol/L.
Can I raise my eGFR?
Controlling blood pressure and blood sugar, avoiding medicines that harm the kidneys such as regular NSAID use, not smoking and following your doctor’s advice can help protect kidney function.
Is this calculator suitable for children?
No. CKD-EPI is for adults aged 18 and over. Children’s kidney function is estimated with different equations, such as the bedside Schwartz equation.
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Sources
Last reviewed: October 2026. This calculator is for information only and does not replace advice from a doctor or other qualified health professional.