eGFR Calculator (CKD-EPI 2021)
Estimate Glomerular Filtration Rate to assess kidney function.
What is GFR?
Glomerular Filtration Rate (GFR) is the best way to measure your level of kidney function and determine your stage of kidney disease. Your GFR is calculated from the results of your blood creatinine test, age, and biological sex. It tells your doctor how many milliliters of blood your kidneys filter per minute, adjusted for your body surface area.
How is eGFR Calculated?
This calculator uses the CKD-EPI (2021) formula, which is the current clinical standard. Unlike older formulas, the 2021 CKD-EPI equation does not use a race variable, making it more accurate for a diverse population. The math involves:
- Serum Creatinine: A waste product from muscle breakdown filtered by kidneys.
- Age: Kidney function naturally declines as we age.
- Sex: Males typically have higher muscle mass and creatinine production than females.
Understanding Your Results
A normal GFR is usually above 90. Here is how medical professionals generally categorize kidney function:
| Stage | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| Stage 1 | 90 or higher | Normal kidney function |
| 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 (ESRD) |
Example Calculation
If a 55-year-old male has a serum creatinine of 1.2 mg/dL:
- Input: Creatinine: 1.2, Age: 55, Sex: Male.
- Result: Approximately 76 mL/min/1.73m².
- Status: This would be considered Stage 2 (Mildly decreased function).
Disclaimer: This calculator is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician regarding kidney health.