eGFR Kidney Function Calculator
Estimate your Glomerular Filtration Rate using the 2021 CKD-EPI formula.
How Kidney Function is Calculated
Kidney function is primarily measured using the Estimated Glomerular Filtration Rate (eGFR). This value represents how many milliliters of blood your kidneys filter per minute. Since it is difficult to measure directly, doctors use formulas based on markers in your blood, most commonly creatinine.
This calculator uses the CKD-EPI (2021) equation, which is currently the clinical standard. It provides an estimate based on your serum creatinine level, age, and biological sex, without requiring a race-based adjustment.
Understanding Your Results
A normal eGFR for adults is usually above 90 mL/min/1.73m². However, GFR naturally declines with age. Below is the standard classification for Chronic Kidney Disease (CKD) stages:
| Stage | eGFR Level | Description |
|---|---|---|
| Stage 1 | 90 or higher | Normal kidney function, but other signs of kidney damage may be present. |
| Stage 2 | 60 – 89 | Mildly decreased kidney function. |
| Stage 3a | 45 – 59 | Mild to moderate decrease in kidney function. |
| Stage 3b | 30 – 44 | Moderate to severe decrease in kidney function. |
| Stage 4 | 15 – 29 | Severely decreased kidney function. |
| Stage 5 | Less than 15 | Kidney failure (Requires dialysis or transplant). |
Why Creatinine Matters
Creatinine is a waste product that comes from the normal wear and tear on muscles of the body. Healthy kidneys filter creatinine from the blood and pass it out of the body through urine. When the kidneys are not working properly, creatinine builds up in the blood. Therefore, a high serum creatinine level often indicates low kidney function.
Important Considerations
While the eGFR is a powerful tool, it may not be accurate for everyone. Factors that can skew the results include:
- Extreme body size (severe obesity or malnutrition).
- Pregnancy.
- High muscle mass (athletes or bodybuilders).
- Recent consumption of cooked meat.
- Use of certain medications or supplements (like creatine).
Disclaimer: This calculator is for educational purposes only. Always consult with a healthcare professional to interpret your lab results and diagnose medical conditions.