GFR Calculator
Estimate your Glomerular Filtration Rate (GFR) to assess kidney function. Compare results from multiple formulas including MDRD, CKD-EPI, and Mayo Quadratic.
What is Glomerular Filtration Rate (GFR)?
Glomerular filtration rate describes the rate of flow of filtered fluids through the kidney and is used as a measure of kidney function. Generally, a higher value of GFR indicates better kidney function. A significant decrease in GFR indicates that the kidney is not properly functioning, resulting in lower volumes of fluids being filtered over a given time.
The normal range of GFR adjusted for body surface area is 100 to 130 mL/min/1.73m² in men and 90 to 120 mL/min/1.73m² in women below the age of 40. After age 40, GFR decreases progressively with age.
Population Mean Estimated GFR
| Age | Mean Estimated GFR (mL/min/1.73 m²) |
|---|---|
| 20-29 | 116 |
| 30-39 | 107 |
| 40-49 | 99 |
| 50-59 | 93 |
| 60-69 | 85 |
| 70+ | 75 |
Chronic Kidney Disease Stages
A GFR above 60 mL/min/1.73m² is usually adequate for most patients and alone is not necessarily indicative of a patient having chronic kidney disease (CKD). However, if there has been a significant decline of GFR since a previous test, this could be an early indicator of kidney disease. Note that the sooner that kidney disease is diagnosed and treated, the higher the probability that the need for dialysis can be prevented.
| Stage | GFR Value (mL/min/1.73 m²) | Description |
|---|---|---|
| Normal | 90+ | Normal kidney function |
| CKD1 | 90+ | Kidney damage with normal GFR |
| CKD2 (Mild) | 60-89 | Mild kidney damage |
| CKD3 (Moderate) | 30-59 | Moderate kidney damage |
| CKD4 (Severe) | 15-29 | Severe kidney damage |
| CKD5 (Kidney Failure) | <15 | Kidney failure |
Measuring GFR
The most accurate way to determine GFR involves the measurement of the rate at which an external substance such as inulin is removed from the bloodstream, termed inulin clearance. However, this measurement method requires continuous intravenous infusion, a number of blood and urine collections, and proper timing of blood samples, making it impractical for routine clinical use.
As such, many formulas have been developed to estimate GFR, many of which are based on creatinine clearance, or estimates of creatinine clearance based on serum creatinine levels. Creatinine clearance does, however, have the limitation of being affected by muscle mass. Higher muscle mass increases serum creatinine for any given rate of clearance.
Important: This calculator provides estimates only and should not replace professional medical advice. GFR calculations are tools to help assess kidney function, but actual diagnosis and treatment decisions should be made by qualified healthcare professionals. If you have concerns about your kidney function, please consult with your doctor.