Kidney function category tool
CKD Stage Calculator: Map eGFR to KDIGO G1-G5
Identify the GFR category for an adult eGFR result while keeping a numerical category separate from a CKD diagnosis.
Use the eGFR value from your laboratory report or calculate it with our CKD-EPI 2021 eGFR calculator.
A CKD stage cannot be diagnosed from one eGFR result alone. CKD generally requires persistent findings for at least three months and may also involve urine albumin or other evidence of kidney damage.
How this tool works
The tool applies the KDIGO GFR boundaries exactly: G1 is 90 or higher, G2 is 60-89, G3a is 45-59, G3b is 30-44, G4 is 15-29, and G5 is below 15 mL/min/1.73 m². An eGFR of exactly 15 is therefore G4, not G5.
CKD classification is broader than the G category. KDIGO uses cause, GFR category, and albuminuria category together. A complete evaluation may also use urine sediment, imaging, pathology, trends, symptoms, and other markers of kidney damage.
How to use it
- Enter the adult indexed eGFR value from a laboratory report, expressed in mL/min/1.73 m².
- Read the returned G category and range, then check whether the finding has persisted for at least three months or another kidney-damage marker is present.
- Review urine albumin-to-creatinine ratio and the direction and speed of change with a healthcare professional.
How to interpret the result
G1 and G2 do not meet CKD criteria without evidence of kidney damage. G3a-G5 fall below 60, but acute kidney injury and other temporary changes must be distinguished from chronic disease.
A G category does not by itself predict an individual's prognosis or determine treatment. Albuminuria, cause, age, cardiovascular risk, diabetes, blood pressure, medicines, and prior results all affect clinical decisions.
Limitations and safety
- Use an adult laboratory eGFR, not Cockcroft-Gault CrCl, an unindexed measured clearance, or a pediatric estimate without pediatric interpretation.
- The tool cannot establish chronicity, identify the cause, or detect acute kidney injury from a single number.
- Very low, rapidly falling, or symptom-associated results require prompt clinical assessment; this page is not emergency triage.
Sources and method
Formula and interpretation checked against the following primary or authoritative sources. Editorial review date: September 9, 2026.