eGFR Calculator (CKD-EPI 2021)
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Female
Typical range: 0.6 to 1.3 mg/dL
Please enter valid values for age and creatinine.
Estimated GFR
Understanding Glomerular Filtration Rate (GFR)
The Glomerular Filtration Rate (GFR) is widely considered the best overall index of kidney function. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. This calculator uses the CKD-EPI 2021 creatinine equation, which is currently recommended by the National Kidney Foundation as it provides a more accurate estimate without relying on race as a variable.
How the Calculation Works
This calculator determines your Estimated GFR (eGFR) based on three primary factors:
- Serum Creatinine: A waste product generated by muscle metabolism. Healthy kidneys filter creatinine out of the blood. High levels usually indicate impaired kidney function.
- Age: GFR naturally declines slightly as we age.
- Biological Sex: Muscle mass differences between males and females affect creatinine generation rates.
Interpreting Your GFR Results
The results are measured in mL/min/1.73m². In adults, a GFR of over 90 is considered normal, provided there are no other signs of kidney damage.
| CKD Stage | GFR Range | Kidney Function Status |
|---|---|---|
| Stage 1 | 90 or higher | Normal function (if other signs of kidney damage are present) |
| Stage 2 | 60 – 89 | Mildly decreased function |
| Stage 3a | 45 – 59 | Mild to moderate decrease |
| Stage 3b | 30 – 44 | Moderate to severe decrease |
| Stage 4 | 15 – 29 | Severely decreased function |
| Stage 5 | Less than 15 | Kidney failure (End Stage Renal Disease) |
When to Consult a Doctor
An eGFR below 60 mL/min/1.73m² for more than three months may indicate Chronic Kidney Disease (CKD). However, a single test result does not constitute a diagnosis. Factors such as dehydration, high-protein diets, or certain medications can temporarily affect creatinine levels.
If your calculation shows a reduced GFR, it is critical to consult a healthcare professional for a comprehensive evaluation, which may include urine tests (albumin-to-creatinine ratio) and imaging.