estimated glomerular filtration rate calculator

What is eGFR?

eGFR stands for estimated glomerular filtration rate. It is a blood-test-based estimate of how well your kidneys filter waste and excess fluid. The result is typically shown in mL/min/1.73m², which standardizes kidney function to a typical body surface area.

Doctors often review eGFR alongside other data like urine albumin, blood pressure, and medical history. A single eGFR value is useful, but trends over time usually provide better clinical insight.

How this calculator works

This page uses the 2021 CKD-EPI creatinine equation, a widely used adult equation that does not include race as a variable. It estimates kidney filtration from:

• Age
• Sex at birth
• Serum creatinine

If you enter creatinine in µmol/L, the calculator automatically converts it to mg/dL before applying the equation.

How to interpret your result

General eGFR categories (G stages)

• G1: 90 or higher (normal or high, depending on other findings)
• G2: 60–89 (mildly decreased)
• G3a: 45–59 (mild to moderate decrease)
• G3b: 30–44 (moderate to severe decrease)
• G4: 15–29 (severely decreased)
• G5: below 15 (kidney failure range)

These categories do not diagnose chronic kidney disease by themselves. CKD diagnosis generally requires persistent abnormalities for at least 3 months and may include albuminuria or structural kidney changes.

Important limitations

eGFR equations are estimates. Accuracy can be reduced in certain situations, including:

• Acute kidney injury (rapidly changing kidney function)
• Pregnancy
• Extremes of muscle mass (very low or very high)
• Recent major illness, hospitalization, or dehydration
• Children and adolescents (this calculator is for adults)

When to speak with a healthcare professional

Consider medical follow-up if:

• Your eGFR is repeatedly below 60
• Your eGFR declines significantly over time
• You have diabetes, hypertension, or cardiovascular disease
• You notice swelling, foamy urine, fatigue, or reduced urine output

A clinician may order repeat blood work, urine albumin-to-creatinine ratio (uACR), and blood pressure checks to build a full kidney-risk profile.

Ways to support kidney health

• Keep blood pressure and blood sugar in target range
• Avoid smoking and limit excess alcohol
• Use NSAIDs cautiously and only as advised
• Stay hydrated and follow a balanced, lower-sodium diet
• Stay physically active and maintain a healthy weight
• Attend regular follow-up visits if you have CKD risk factors

Quick FAQ

Is a single low eGFR always serious?

Not always. Temporary changes can happen due to hydration status, illness, medications, or lab variation. Repeat testing is often needed.

Can eGFR improve?

It can improve if a reversible issue is corrected (for example, dehydration or medication effects). In chronic disease, slowing decline is often the key goal.

Why does age affect eGFR?

Kidney filtration naturally declines with age, so age is built into modern estimating equations.