Kidney function
eGFR calculator
Estimate your glomerular filtration rate from your creatinine, age, and sex using the race-free CKD-EPI 2021 equation, and see the corresponding kidney-function stage explained.
Enter your values above to see your result and what it means.
What is eGFR and what does it measure?
eGFR stands for estimated glomerular filtration rate — an estimate of how much blood your kidneys filter each minute, scaled to body size and reported in mL/min/1.73m². It is calculated from a blood creatinine level together with your age and sex, not measured directly. Because it is an estimate, it gives a useful overall picture of kidney function rather than an exact figure.
The CKD-EPI 2021 formula explained
This calculator uses the CKD-EPI 2021 creatinine equation, the current race-free formula recommended for estimating GFR in adults. It takes your creatinine, age, and sex and returns an eGFR value. Different equations and lab methods can produce slightly different numbers, so compare this estimate with the eGFR printed on your own report.
What is a normal eGFR range?
An eGFR of 90 mL/min/1.73m² or above is generally considered normal kidney filtration, and 60 or above is usually regarded as adequate when there is no other evidence of kidney damage. Below 60 sustained for three months or more is the threshold that defines chronic kidney disease. Because eGFR is an estimate, a single reading can be shifted by hydration, a recent meal, muscle mass, or certain medicines, which is why staging relies on repeated results rather than one number. Read this estimate alongside the eGFR printed on your own report; different labs and assay methods produce slightly different values.
| Stage | eGFR (mL/min/1.73m²) | What it describes |
|---|---|---|
| G1 | 90 or above | Normal or high filtration |
| G2 | 60 to 89 | Mildly reduced filtration |
| G3a | 45 to 59 | Mild to moderate reduction |
| G3b | 30 to 44 | Moderate to severe reduction |
| G4 | 15 to 29 | Severely reduced filtration |
| G5 | Below 15 | Kidney failure |
Normal eGFR by age
Filtration declines gradually with age, so the same creatinine returns a lower eGFR in an older adult than in a younger one. The CKD-EPI equation already builds age in, which is why you cannot read a creatinine value on its own. The figures below are typical average values rather than thresholds: a result near the average for your age is unremarkable, and a result well below it is worth a conversation even if it has not crossed a stage boundary. Age alone never establishes chronic kidney disease; that requires a reduced eGFR sustained across at least three months, or other evidence of kidney damage.
| Age | Typical average eGFR |
|---|---|
| 20 to 29 | about 116 |
| 30 to 39 | about 107 |
| 40 to 49 | about 99 |
| 50 to 59 | about 93 |
| 60 to 69 | about 85 |
| 70 and over | about 75 |
What does a low eGFR mean, and the CKD stages
Lower eGFR values are grouped into chronic kidney disease (CKD) stages, where smaller numbers indicate more reduced filtering. A single low estimate can be affected by hydration, recent meals, muscle mass, or certain medicines, so staging is based on repeated results over time, not one reading. This tool shows the stage your estimate falls into for information only — it does not diagnose kidney disease.
CKD-EPI vs MDRD: why the numbers differ
You may see an eGFR calculated with the older MDRD equation, which many labs used before the shift to CKD-EPI. The two do not agree, and the disagreement is systematic rather than random: MDRD was derived in a population with reduced kidney function and tends to underestimate eGFR in the near-normal range, so it can place a healthy person in stage G2 or even G3a where CKD-EPI does not. CKD-EPI is more accurate above 60 and is the equation current guidelines recommend. A third point of difference matters historically: both equations originally carried a race coefficient that raised the estimate for Black patients, and the 2021 CKD-EPI refit removed it. This calculator uses the 2021 race-free creatinine equation. If you are comparing an old report with a new one, check which equation each used before concluding that your kidney function has changed.
eGFR and creatinine: how they relate
Creatinine is the waste product the eGFR equation is built around: as kidney filtering falls, creatinine in the blood tends to rise, which lowers the estimated eGFR. That inverse relationship is why a high creatinine often accompanies a low eGFR. Entering your creatinine here lets the calculator turn that raw lab value into the more interpretable eGFR figure.
Frequently asked questions
What is a normal eGFR?
An eGFR of 90 or above is generally considered normal, and 60–89 is common and often normal too, especially with age, if there are no other signs of kidney damage. Below 60 for three months or more is one of the markers used to define chronic kidney disease.
Does one low eGFR mean I have kidney disease?
No. Chronic kidney disease requires a reduced eGFR or other damage markers that last at least three months. A single low result can be caused by dehydration, a recent illness, or certain medicines, so clinicians repeat the test and check urine before concluding anything.
Why does the calculator ask for sex but not race?
The 2021 CKD-EPI equation uses age, sex, and creatinine, and — unlike older versions — does not include a race coefficient. Sex is used because creatinine levels differ with typical muscle mass.
My creatinine is in µmol/L — can I use this?
This calculator expects creatinine in mg/dL. To convert, divide a µmol/L value by 88.4 (for example, 80 µmol/L ÷ 88.4 ≈ 0.9 mg/dL).