Enter the number of items, average covariance between pairs, and the average variance into the calculator to determine Cronbach’s alpha.

Cronbach Alpha Formula

The following formula is used to calculate Cronbach alpha.

a = (N*C) / ( v + (N-1)*C)

  • Where a is the coefficient alpha
  • N is the number of items
  • C is the covariance between item pairs
  • v is the average covariance

Cronbach Alpha Definition

Cronbach’s alpha, also known as coefficient alpha, is a measure of the internal consistency of a test. In other words, how reliable the test is at predicting an outcome.


How to calculate cronbach’s alpha?

  1. First, determine the number of items.

    This is typically the total number of questions on the test.

  2. Next, determine the covariance between items.

    Calculate the covariance between items.

  3. Next, determine the variance average.

    Calculate the average variance of the test.

  4. Finally, calculate the alpha coefficient.

    Calculate the reliability using the formula above.


What is internal consistency?

Internal consistency is a measure of the variance in results between the same test given multiple times.