Cronbach Alpha Calculator
Calculate raw and standardized-item Cronbach alpha plus item variances and descriptive alpha-if-deleted values from a complete respondent matrix.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Compare the sum of item sample variances with sample variance of total scores; evaluate standardized alpha from mean inter-item correlation.
Raw alpha=k/(k−1)×(1−sum item variances/total-score variance)
Worked example
Three item columns that differ only by constants have perfect inter-item correlation. The entered illustrative matrix gives raw and standardized alpha 1.
Assumptions and input details
3–500 complete respondent rows and the same 2–20 item columns. Reverse scoring and missing-data decisions must be completed before entry. Alpha can be negative and is undefined when total-score variance is zero. Standardized alpha requires positive variance in every item. A high alpha does not establish unidimensionality, validity or a recommended item-deletion decision.
References: Primary methodological source: coefficient-alpha definition
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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