CKD-EPI eGFR Calculator (2021)
Estimate kidney function using the CKD-EPI 2021 creatinine equation (race-free). Enter your values below and click calculate.
For education only. This is not a diagnosis and does not replace medical advice.
What is the CKD-EPI calculator?
The CKD-EPI calculator estimates eGFR (estimated glomerular filtration rate), a widely used indicator of kidney function. It uses serum creatinine, age, and sex to estimate how much blood your kidneys filter each minute, normalized to body surface area (mL/min/1.73m²).
Clinicians use eGFR to help screen for chronic kidney disease (CKD), monitor kidney function over time, and guide medication dosing when kidney function is reduced.
Equation used in this tool
This page uses the 2021 CKD-EPI creatinine equation (without a race coefficient):
eGFR = 142 × min(Scr/K, 1)α × max(Scr/K, 1)-1.200 × 0.9938Age × 1.012 (if female)
- Scr: serum creatinine in mg/dL
- K: 0.7 (female), 0.9 (male)
- α: -0.241 (female), -0.302 (male)
- Age in years
If you enter creatinine in µmol/L, the calculator automatically converts it to mg/dL before applying the formula.
How to use the CKD-EPI calculator
- Enter your age.
- Select sex at birth.
- Enter serum creatinine from your blood test report.
- Choose the correct unit (mg/dL or µmol/L).
- Click Calculate eGFR.
The result includes your estimated GFR and a matching CKD G-stage category.
Understanding eGFR stages
| G Stage | eGFR (mL/min/1.73m²) | Interpretation |
|---|---|---|
| G1 | ≥ 90 | Normal or high kidney function (if no other kidney damage markers) |
| 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 | < 15 | Kidney failure range |
Important context for interpretation
A single eGFR value does not automatically mean chronic kidney disease. CKD generally requires abnormalities present for at least 3 months, such as persistently reduced eGFR or markers like albuminuria. Trends over time are often more informative than one isolated result.
Why eGFR can change
Many factors can influence creatinine and eGFR:
- Hydration status
- Recent illness or infection
- Muscle mass and body composition
- Certain medications (for example, trimethoprim, NSAIDs, ACE inhibitors, ARBs, diuretics)
- High meat intake close to testing
Because of this, healthcare professionals often repeat labs and review urine tests before making conclusions.
When to seek medical advice
- eGFR below 60 on repeated tests
- Rapid decline in eGFR over weeks or months
- Swelling, foamy urine, blood in urine, or persistent high blood pressure
- Diabetes, hypertension, or family history of kidney disease
Discuss your labs with your clinician, especially if medication dosing or CKD risk management is needed.
Limitations of online calculators
This CKD-EPI calculator is useful for estimation, but it cannot replace a full medical assessment. It does not include urine albumin-to-creatinine ratio (uACR), imaging results, clinical symptoms, or all causes of kidney injury. For complex cases, nephrology evaluation may be appropriate.