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GFR Calculator 2025

Calculate your Glomerular Filtration Rate instantly with our medically accurate, free GFR calculator trusted by healthcare professionals worldwide. Get kidney function assessment and CKD staging.

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Calculate Your GFR

Enter patient details to get instant, medically accurate kidney function assessment

Adult
18+ years old
Child
Under 18 years
mg/dL
Normal range: 0.6-1.2 mg/dL (men), 0.5-1.1 mg/dL (women)
years

GFR Results

CKD-EPI eGFR:
--
mL/min/1.73m²
MDRD: --
Mayo Quadratic: --

CKD Stages Reference

Stage GFR (mL/min/1.73m²) Description
Normal ≥90 Normal kidney function
CKD 1 ≥90 Normal with kidney damage
CKD 2 60-89 Mild CKD
CKD 3 30-59 Moderate CKD
CKD 4 15-29 Severe CKD
CKD 5 <15 Kidney failure

⚠️ Medical Disclaimer

This GFR calculator is for informational purposes only. Results should not replace professional medical evaluation or diagnosis. GFR estimates may not be accurate in certain conditions. Always consult qualified healthcare professionals for kidney health assessment and treatment decisions.

Understanding GFR & Kidney Function

Comprehensive guide to Glomerular Filtration Rate, kidney function assessment, and chronic kidney disease staging.

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What is GFR?

Glomerular Filtration Rate measures how well your kidneys filter waste from your blood. It's the best overall indicator of kidney function and is used to diagnose and stage chronic kidney disease.

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Normal GFR Values

Normal GFR is 100-130 mL/min/1.73m² for men and 90-120 mL/min/1.73m² for women under 40. GFR naturally declines with age, dropping about 1 mL/min per year after age 40.

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GFR Calculation Methods

GFR is estimated using serum creatinine levels with formulas like CKD-EPI (most accurate), MDRD, and Mayo Quadratic. Each formula accounts for age, gender, and race differently.

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CKD Staging

Chronic Kidney Disease is staged 1-5 based on GFR levels. Stage 3+ (GFR <60) indicates significant kidney disease requiring medical management and monitoring.

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Creatinine Factors

Serum creatinine can be affected by muscle mass, diet, medications, and hydration. Higher muscle mass may lead to higher creatinine without kidney disease.

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Clinical Significance

Early detection of kidney disease allows for interventions to slow progression and prevent complications. Regular GFR monitoring is crucial for patients with diabetes and hypertension.

Frequently Asked Questions

Everything you need to know about GFR calculations, kidney function, and chronic kidney disease answered by medical experts.

What is a normal GFR for my age?

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Normal GFR varies by age. Young adults typically have GFR of 100-130 mL/min/1.73m². GFR naturally declines with age: 20s (116), 30s (107), 40s (99), 50s (93), 60s (85), 70+ (75). Values above 60 are generally considered adequate.

What does a low GFR mean?

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A GFR below 60 mL/min/1.73m² for 3+ months indicates chronic kidney disease. GFR 30-59 is moderate CKD, 15-29 is severe CKD, and below 15 indicates kidney failure requiring dialysis or transplant consideration.

Which GFR formula is most accurate?

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The CKD-EPI formula is currently considered most accurate for adults and is recommended by kidney disease guidelines. It performs better than MDRD, especially at higher GFR levels. Mayo Quadratic may be used for comparison.

Can medications affect my GFR?

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Yes, certain medications can affect creatinine levels and GFR estimates. ACE inhibitors, ARBs, and some antibiotics can temporarily increase creatinine. Always inform your doctor about all medications when interpreting GFR results.

How often should GFR be checked?

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Frequency depends on your risk factors and current kidney function. High-risk patients (diabetes, hypertension) should be checked annually. Those with known CKD may need monitoring every 3-6 months. Your doctor will determine the appropriate schedule.

Can GFR improve over time?

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While chronic kidney disease is generally progressive, GFR can sometimes improve with treatment of underlying causes, better blood pressure/diabetes control, or resolution of acute kidney injury. Early intervention is key to preserving kidney function.