Free GFR Calculator Online
Estimate your kidney function with this free GFR calculator. Enter your age, gender, and serum creatinine level to get your eGFR and CKD stage using CKD-EPI and MDRD formulas — completely free and online.
eGFR (CKD-EPI)
Enter patient data
CKD Stages by GFR
| Stage | GFR (mL/min/1.73m²) | Description | Status |
|---|---|---|---|
| Stage 1 | 90+ | Normal function | |
| 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 |
How the GFR Calculator Works
The GFR calculator uses serum creatinine — a waste product from muscle metabolism — to estimate kidney filtration rate. Higher creatinine usually means lower kidney function. The CKD-EPI formula (recommended since 2021) adjusts for age and sex to provide the most accurate estimate for the general population.
The MDRD formula was the previous standard and is still widely used. Both formulas normalize results to a standard body surface area of 1.73 m². The GFR calculator shows results from both formulas so you can see how they compare for your specific values.
A single GFR result is a snapshot, not a diagnosis. Chronic kidney disease requires persistently low GFR (below 60) for at least 3 months. The GFR calculator helps you track trends, but always discuss results with your healthcare provider.
Protecting Your Kidney Health
Control Blood Pressure
Hypertension is a leading cause of kidney damage. Target below 130/80 mmHg. The GFR calculator helps you monitor kidney function if you have hypertension.
Manage Blood Sugar
Diabetes is the most common cause of kidney disease. Keeping A1C below 7% significantly reduces kidney damage risk.
Stay Hydrated
Adequate water intake helps kidneys clear waste efficiently. Aim for 6–8 glasses daily, more if you are active.
Avoid Nephrotoxic Drugs
NSAIDs (ibuprofen, naproxen) can harm kidneys with prolonged use. Always follow dosing guidelines and consult your doctor.
Frequently Asked Questions
Disclaimer: This free online GFR calculator provides estimates based on standard formulas. It is not a substitute for laboratory testing or medical diagnosis. Always consult a nephrologist or healthcare provider for interpretation of kidney function tests.
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