eGFR calculator (CKD-EPI 2021)
Estimate glomerular filtration rate (GFR) in adults from serum creatinine, age and sex. This calculator uses the race-free CKD-EPI 2021 creatinine equation and shows the matching KDIGO GFR category.
How this eGFR calculator works
This eGFR calculator uses the CKD-EPI 2021 creatinine equation, published by Inker and colleagues in the New England Journal of Medicine in 2021. The equation estimates GFR, in mL/min per 1.73 m² of body surface area, from serum creatinine, age and sex, and unlike the 2009 version it has no race term. In 2021 the US National Kidney Foundation and American Society of Nephrology task force recommended it for adults in the United States. Creatinine in µmol/L is divided by 88.4 to convert it to mg/dL before the equation runs.
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938age × 1.012 (if female)
Scr = serum creatinine in mg/dL. κ = 0.7 for females, 0.9 for males. α = −0.241 for females, −0.302 for males.
eGFR categories (KDIGO)
KDIGO groups GFR into six categories. A GFR under 60 for more than 3 months meets the KDIGO definition of chronic kidney disease (CKD) on its own. Categories G1 and G2 count as CKD only when there are also markers of kidney damage, such as albuminuria, lasting more than 3 months.
| Category | eGFR (mL/min/1.73 m²) | 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 | Under 15 | Kidney failure |
When creatinine-based eGFR is less accurate
The equation assumes creatinine is stable, so it does not reflect GFR during acute kidney injury, when creatinine is still rising or falling. It is also less reliable when muscle mass is far from average, for example in amputation, paralysis, muscle-wasting disease, very high muscle mass or high creatine intake, and in pregnancy. It was not developed for people under 18. In these cases KDIGO suggests confirming with cystatin C or a measured GFR.
Questions
What is a normal eGFR?
An eGFR of 90 mL/min/1.73 m² or more is category G1, normal or high. GFR falls slowly with age, so values between 60 and 89 are common in older adults and count as CKD only with other signs of kidney damage.
Why does CKD-EPI 2021 have no race term?
The 2009 CKD-EPI equation gave a higher eGFR to people identified as Black. The 2021 refit removed race, and the NKF and ASN task force recommended the new equation so that eGFR no longer depends on race.
Can I enter creatinine in µmol/L?
Yes. Pick µmol/L under the creatinine box. The calculator divides by 88.4 to get mg/dL before it runs the equation.
Is my data sent anywhere?
No. The calculation runs in your browser, and the values you type are not sent or stored.
Sources
- Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C–based equations to estimate GFR without race. N Engl J Med. 2021;385:1737–1749. doi:10.1056/NEJMoa2102953
- Delgado C, Baweja M, Crews DC, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force. Am J Kidney Dis. 2022;79(2):268–288. doi:10.1053/j.ajkd.2021.08.003
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314. doi:10.1016/j.kint.2023.10.018