Glomerular Filtration Rate (GFR) Calculator

Estimate your kidney function by calculating your Glomerular Filtration Rate (GFR), which measures how well your kidneys filter waste from your blood.

Disclaimer: This tool provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.

Understanding Your Glomerular Filtration Rate (GFR)

GFR is the best overall measure of kidney function. It calculates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A higher GFR indicates better kidney function, while a lower GFR suggests impaired kidney function.

Why GFR Matters

Chronic Kidney Disease (CKD) affects millions worldwide and often goes undetected until advanced stages. Regular GFR estimation helps in early detection and management of kidney disease, potentially preventing complications like cardiovascular disease and kidney failure.

How to Measure Accurately

For accurate results:

Use recent blood test results for creatinine levels
Fast for 8-12 hours before blood tests for most accurate readings
Avoid strenuous exercise 48 hours before testing

GFR Reference Table

GFR Range (mL/min/1.73m²)	CKD Stage	Kidney Function
≥90	1	Normal or high
60-89	2	Mildly decreased
45-59	3a	Mild to moderately decreased
30-44	3b	Moderately to severely decreased
15-29	4	Severely decreased
<15	5	Kidney failure

Important Considerations

GFR estimates are not accurate for everyone. Results may be less reliable for:

Pregnant women
People with extremely large or small muscle mass
Those with rapidly changing kidney function
People with unusual dietary patterns (vegetarians, creatine supplements)

Always consult a healthcare professional for proper kidney function evaluation and interpretation of your results.

Frequently Asked Questions

What's the difference between GFR and creatinine clearance?

GFR is a calculated estimate of kidney function, while creatinine clearance requires a 24-hour urine collection. GFR is now the standard measurement used by nephrologists.

Why does the formula include race?

The race coefficient accounts for observed differences in average creatinine levels between Black and non-Black populations. Note that many medical organizations are reconsidering this approach.

How often should I check my GFR?

Frequency depends on your health status. Those with risk factors (diabetes, hypertension) should be tested annually. People with known kidney disease may need more frequent monitoring.

Can GFR improve over time?

While kidney damage is often permanent, addressing underlying causes (like controlling blood pressure and blood sugar) can sometimes slow decline or slightly improve function.

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Glomerular Filtration Rate (GFR) Calculator

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