GFR Calculator
Estimate Glomerular Filtration Rate (eGFR) to assess kidney function. GFR measures how well your kidneys filter waste from the blood, expressed in mL/min/1.73m². This calculator uses the CKD-EPI, MDRD, and Cockcroft-Gault equations based on serum creatinine, age, and gender.
What is GFR?
Glomerular Filtration Rate (GFR) is the best overall measure of kidney function. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A normal GFR is above 90 mL/min/1.73m². Lower values indicate reduced kidney function.
GFR Formulas
CKD-EPI: 141 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.209 × 0.993^Age × [1.018 if female]
MDRD: 175 × Scr^-1.154 × Age^-0.203 × [0.742 if female]
Cockcroft-Gault: [(140 - Age) × Weight × (0.85 if female)] / (72 × Scr)
CKD Stages by GFR
| Stage | GFR (mL/min) | Description |
|---|---|---|
| Stage 1 | ≥ 90 | Normal or high |
| Stage 2 | 60–89 | Mildly decreased |
| Stage 3a | 45–59 | Mild to moderate decrease |
| Stage 3b | 30–44 | Moderate to severe decrease |
| Stage 4 | 15–29 | Severely decreased |
| Stage 5 | < 15 | Kidney failure |
Frequently Asked Questions
What is a normal GFR?
A normal GFR is 90 mL/min/1.73m² or higher. GFR naturally declines with age — a healthy 70-year-old may have a GFR of 70-80, which is considered normal for their age.
What does low GFR mean?
A GFR below 60 for 3 or more months indicates chronic kidney disease (CKD). Below 15 indicates kidney failure requiring dialysis or transplant.
Which GFR formula is most accurate?
The CKD-EPI equation (2009) is currently recommended by KDIGO guidelines as the most accurate for most adults. The MDRD equation tends to underestimate GFR in healthy individuals.
Can GFR be improved?
In early stages, GFR can be stabilized or improved through blood pressure control, diabetes management, reducing protein intake, staying hydrated, and avoiding nephrotoxic drugs (like NSAIDs).
What is creatinine?
Creatinine is a waste product from normal muscle metabolism. Healthy kidneys filter it out of the blood. High creatinine levels suggest the kidneys are not filtering effectively, which correlates with low GFR.