eGFR Calculator
Estimated GFR, mL/min/1.73 m²
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Enter an age and a serum creatinine.
- KDIGO category
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The working
This works out the arithmetic. The order, the product in your hand and local policy still govern what is given.
How CKD-EPI 2021 works
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 if female
κ is 0.7 for women and 0.9 for men, and α is −0.241 and −0.302 respectively. The two-part structure lets the equation behave differently above and below the sex-specific creatinine threshold, which is what the min and max terms select between.
A 60-year-old man with a creatinine of 1.0 mg/dL comes out at 86.2 mL/min/1.73 m². The result is per 1.73 m² of body surface area, not for the person's own size, which is the difference between this and a creatinine clearance.
Why the race coefficient was removed
The 2009 CKD-EPI equation included a coefficient that raised the reported eGFR for patients recorded as Black. A higher reported eGFR means kidney disease looks less advanced, which delays referral, transplant listing and dose adjustment.
A joint task force of the National Kidney Foundation and the American Society of Nephrology recommended moving to an equation without that term, and the 2021 refit is the result. This calculator runs only the 2021 equation, so it has no race input to offer.
KDIGO GFR categories
| Category | eGFR (mL/min/1.73 m²) | Description |
|---|---|---|
| G1 | 90 and above | Normal or high |
| G2 | 60 to 89 | Mildly decreased |
| G3a | 45 to 59 | Mildly to moderately decreased |
| G3b | 30 to 44 | Moderately to severely decreased |
| G4 | 15 to 29 | Severely decreased |
| G5 | Under 15 | Kidney failure |
The category is a band, not a diagnosis. Staging chronic kidney disease also requires albuminuria and abnormality persisting over three months.
Questions about eGFR
- What is the CKD-EPI 2021 equation?
- The current creatinine-based equation for estimating glomerular filtration rate. It was published in 2021 to replace the 2009 version, whose Black race coefficient raised the reported eGFR for Black patients and was removed on the grounds that race is a social rather than a biological variable.
- Why does this calculator not ask about race?
- Because the equation it runs does not use it. The 2021 equation was derived without a race term, which is the point of it. Any eGFR calculator still asking for race is running the older 2009 equation.
- What is a normal eGFR?
- 90 mL/min/1.73 m² or above is categorised as normal or high, though eGFR declines with age and a value in the 60s in an older adult is not automatically disease. Chronic kidney disease is defined by abnormality persisting over three months, so a single reading does not stage anything on its own.
- Why is my eGFR different from my creatinine clearance?
- They are different measures. eGFR is normalised to a body surface area of 1.73 m²; Cockcroft-Gault creatinine clearance is not. For a person larger or smaller than average the two will diverge, and both can be correct.