How to use this tool
- Enter the serum creatinine from your blood test and choose its unit.
- Enter age and sex.
- Read the eGFR and KDIGO stage. CKD stages G1 and G2 also need other evidence of kidney damage, such as protein in the urine.
The CKD-EPI 2021 equation
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938age × 1.012 (if female), where Scr is serum creatinine in mg/dL, κ is 0.7 for females and 0.9 for males, and α is −0.241 for females and −0.302 for males.
The 2021 version removed the race coefficient used in earlier equations. It was adopted by the National Kidney Foundation and American Society of Nephrology task force, and most US laboratories now report it. UK laboratories have also moved to CKD-EPI.
KDIGO GFR categories
| Stage | eGFR | Description |
|---|---|---|
| G1 | 90 or more | Normal or high |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mildly to moderately decreased |
| G3b | 30–44 | Moderately to severely decreased |
| G4 | 15–29 | Severely decreased |
| G5 | below 15 | Kidney failure |
CKD is diagnosed when eGFR stays below 60 for at least three months, or when there is other evidence of kidney damage such as albuminuria. Staging also uses the urine albumin-to-creatinine ratio (A1–A3).
Frequently asked questions
What is a normal eGFR?
90 mL/min/1.73 m² or more in younger adults. eGFR falls gradually with age.
Does eGFR 55 mean kidney disease?
If it stays below 60 for three months or more, it meets the definition of CKD stage G3a. A doctor will repeat the test and check urine protein.
How do I convert creatinine µmol/L to mg/dL?
Divide by 88.4. 97 µmol/L is about 1.1 mg/dL.
Why was race removed from the equation?
The 2021 equation was developed to estimate GFR accurately without using race, following an NKF–ASN task force recommendation.
Sources and references
- Inker LA et al. New creatinine- and cystatin C–based equations to estimate GFR without race. NEJM 2021;385:1737–49
- National Kidney Foundation: CKD-EPI creatinine equation (2021)
- KDIGO 2024 Clinical Practice Guideline for CKD