How to use this calculator
- Enter or choose serum creatinine.
- Enter or choose creatinine unit.
- Enter or choose age.
- Enter or choose sex.
- The eGFR updates as you type. Use Copy result or Share to keep it.
Method
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × 1.012 [if female]; κ = 0.7 (F) or 0.9 (M); α = −0.241 (F) or −0.302 (M)
- Scr
- serum creatinine in mg/dL (µmol/L ÷ 88.4)
- Age
- age in years (adults only)
- κ, α
- sex-specific constants
Worked example
- Scr/κ = 1.0 ÷ 0.9 = 1.111, so the min term is 1 and the max term is 1.111^−1.200 = 0.881.
- Age term: 0.9938^50 = 0.733.
- eGFR = 142 × 0.881 × 0.733 ≈ 91.7, reported as 92 mL/min/1.73 m².
A 50-year-old man with a creatinine of 1.0 mg/dL has an eGFR of about 92 mL/min/1.73 m², KDIGO category G1.
What the result means
KDIGO categories: G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 < 15 mL/min/1.73 m². Chronic kidney disease is diagnosed only when a reduced GFR or kidney damage (such as albumin in the urine) persists for more than three months, so one result on its own is not a diagnosis.
Assumptions and limits
- Adult (18 or over) with stable kidney function.
- Creatinine measured with an IDMS-traceable method.
- Result is indexed to a standard body surface area of 1.73 m².
- Unreliable in acute kidney injury, pregnancy, very high or very low muscle mass (amputation, bodybuilding, frailty), high-protein diets or creatine supplements, and some medicines that change creatinine.
- For drug dosing, the product label may specify Cockcroft–Gault creatinine clearance or a non-indexed GFR.
- Cystatin C–based equations may be preferred when creatinine is misleading.
Questions
Why does the 2021 equation not use race?
The CKD-EPI 2021 refit removed the race coefficient used in the 2009 equation, so eGFR now depends only on creatinine, age and sex.
Is my eGFR low because of age?
eGFR falls gradually with age in most people. Whether a value matters depends on trends over time, urine albumin and other findings, which a clinician interprets.
Sources
Please note: This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.