eGFR Calculator (CKD-EPI 2021)
Estimated glomerular filtration rate from serum creatinine, age and sex, with CKD stage.
The 2021 CKD-EPI equation is eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 if female, with κ = 0.7 (female) or 0.9 (male). A 50-year-old man with creatinine 1.0 mg/dL has an eGFR of about 92.
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How to use it
- Enter serum creatinine and choose the unit.
- Enter age and sex.
- Read eGFR in mL/min/1.73 m² and the CKD stage (G1–G5).
What you enter
- Serum creatinine
- Age
- Sex
What you get
- eGFR (mL/min/1.73 m²)
- KDIGO GFR category
Formula
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × 1.012 [if female]
κ = 0.7 (female) or 0.9 (male); α = −0.241 (female) or −0.302 (male); Scr in mg/dL.
Worked example
Input: Man, 50 years, creatinine 1.0 mg/dL
Result: eGFR ≈ 92 mL/min/1.73 m², stage G1
Normal filtration; CKD would also need signs of kidney damage such as albuminuria.
Questions
What is a normal eGFR?
90 or above is normal. 60–89 is mildly reduced and may be normal for older adults. Below 60 for three months or more indicates chronic kidney disease.
Why was race removed from the eGFR equation?
In 2021 the NKF and ASN task force recommended a race-free CKD-EPI equation because race is a social, not biological, category and the old coefficient delayed care for Black patients.
Can eGFR be wrong?
Yes. Creatinine depends on muscle mass, so eGFR can mislead in very muscular, frail or amputee patients, in pregnancy and when kidney function is changing quickly. Cystatin C helps in these cases.
How do I convert creatinine µmol/L to mg/dL?
Divide by 88.4. 88 µmol/L is about 1.0 mg/dL.
Limitations
- Not for acute kidney injury or children under 18.
- Drug dosing may need Cockcroft-Gault creatinine clearance instead.
References
- Inker LA et al. (2021) New England Journal of Medicine 385:1737-1749.
- Kidney International (2024) 105(4S):S117-S314.
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