GFR Calculator: Estimate Kidney Function (Glomerular Filtration Rate)
Free estimated GFR (eGFR) from serum creatinine — adult and pediatric modes. Results in mL/min/1.73 m² using MDRD, CKD-EPI, Mayo Quadratic, and Schwartz.
Inputs
Results
| Equation | eGFR (mL/min/1.73 m²) |
|---|---|
| MDRD (IDMS-traceable) | — |
| CKD-EPI 2009 (creatinine) | — |
| Mayo Quadratic | — |
| Schwartz | — |
Educational estimate only; not a medical diagnosis.
The Glomerular Filtration Rate (GFR) is the best overall indicator of kidney function. It measures how well your kidneys are filtering waste from your blood.
Our free GFR Calculator provides accurate estimates using the most widely used medical formulas: MDRD, CKD-EPI (2009), and Mayo Quadratic for adults, plus the Schwartz formula for children.
Important: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice or laboratory testing. Always consult a doctor for health-related decisions.
How Our GFR Calculator Works
Choose Adult 18+ or Child ≤18 at the top of the calculator; each mode applies the appropriate formulas.
For Adults (18+ years)
- MDRD Formula (Modification of Diet in Renal Disease)
- CKD-EPI 2009 creatinine equation (race-inclusive)
- Mayo Quadratic Equation
For Children (≤18 years)
- Schwartz Formula
Inputs required
- Age (adults: 18+)
- Sex
- Serum creatinine (mg/dL or µmol/L)
- Race (for MDRD and CKD-EPI in adult mode)
- Height (children only; cm or ft/in)
These equations do not require body weight. All results are shown in mL/min/1.73 m² (standardized to body surface area).
Understanding Your GFR Results
The table below summarizes typical GFR ranges and CKD stages for context. Staging in real clinical practice also depends on urine findings, albuminuria, and trends — not GFR alone.
| GFR (mL/min/1.73 m²) | Stage | Meaning |
|---|---|---|
| 90 or above | G1 | Normal or high kidney function |
| 60–89 | G2 | Mildly decreased |
| 45–59 | G3a | Mild to moderate decrease |
| 30–44 | G3b | Moderate to severe decrease |
| 15–29 | G4 | Severe decrease |
| Below 15 | G5 | Kidney failure |
Why Use This GFR Calculator?
- Get three adult estimates at once for better comparison
- Supports both mg/dL and µmol/L creatinine units
- Includes pediatric calculation using the Schwartz formula
- Fast, free, and easy to use
- Helps you understand kidney health trends over time (alongside labs from your care team)
Note on race: This calculator uses the classic 2009 CKD-EPI equation with race adjustment, consistent with many clinical references. Newer race-free equations are available but not used here to match standard reference calculator behavior.
Who Should Use a GFR Calculator?
- People with diabetes, high blood pressure, or family history of kidney disease
- Athletes monitoring long-term health
- Individuals taking medications that affect kidney function
- Anyone curious about their kidney health
Tips for Healthy Kidneys
- Stay well hydrated
- Control blood pressure and blood sugar
- Maintain a healthy weight
- Avoid excessive use of NSAIDs (painkillers)
- Get regular check-ups if you have risk factors