Calculate the Changeover Time Available and the Number of Changeovers Possible. The Changeover Time Available is calculated by subtracting the Total Run Time from the Available Work Minutes (shown at the top of the worksheet). The Number of Changeovers Possible is calculated by dividing the Changeover Time Available by the Average Changeover Time. Write your answers in the space provided at the top of the worksheet. Average Changeover Time is 60 minutes.