Health & Body Composition
GFR Calculator
Your kidneys filter about 180 litres of blood a day. eGFR estimates how well they're doing it, a key number in kidney health.
GFR (glomerular filtration rate) estimates how many millilitres of blood the kidneys filter per minute. eGFR of 90 or above is normal; below 60 for three months or more may indicate chronic kidney disease. Results are screening estimates, not diagnoses — confirm with a clinician before acting on them.
Normal: eGFR ≥ 90.
Below 60 = possible CKD.
Below 15 = kidney failure stage.
Calculate Your GFR
Your eGFR
What Is GFR?
Glomerular filtration rate (GFR) measures how much blood the kidneys filter per minute. Because GFR can't be measured directly outside a lab, it's estimated (eGFR) from serum creatinine, age, and sex.
This calculator uses the CKD-EPI 2021 equation, the current reference standard, and also shows the Cockcroft-Gault creatinine clearance still used for drug dosing.
How It Is Calculated
CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × [1.012 if female]
Example: Example: 55-year-old man, creatinine 1.0 mg/dL → eGFR ≈ 90 mL/min/1.73 m²
CKD stages by eGFR (KDIGO)
| Stage | eGFR (mL/min/1.73 m²) | Meaning |
|---|---|---|
| G1 | ≥ 90 | Normal or high |
| G2 | 60–89 | Mildly reduced |
| G3a | 45–59 | Mild–moderate reduction |
| G3b | 30–44 | Moderate reduction |
| G4 | 15–29 | Severe reduction |
| G5 | < 15 | Kidney failure |
Limitations
- Creatinine rises with muscle mass, very muscular people can show falsely low eGFR.
- eGFR varies day to day; trends matter more than single values.
- Not valid during pregnancy or in acute illness.
- Only a clinician can diagnose CKD, eGFR plus urine albumin are used together.
Sources & Review
References used for this calculator’s formulas and thresholds:
GFR FAQ
What is a normal GFR?
90 mL/min/1.73 m² or above is normal. Values of 60–89 with no other kidney damage are usually acceptable in older adults.
What GFR indicates kidney disease?
eGFR below 60 for three months or more, or kidney damage markers like albuminuria at any eGFR, may indicate chronic kidney disease.
How can I improve my eGFR?
Control blood pressure and diabetes, stay hydrated, avoid routine NSAIDs, and limit salt. Some decline with age is normal; slowing it's the goal.
Which is better, CKD-EPI or Cockcroft-Gault?
CKD-EPI 2021 is the standard for staging kidney function. Cockcroft-Gault is still used for many drug-dose adjustments.
A note before you begin: this tool offers educational estimates only. It cannot replace advice from your doctor or another qualified professional.