Determine the value to use from the end of the period being analyzed, and the value to use from the beginning of the period being analyzed. For example, a company wants to find the absolute percent variance of its revenues between 2008 and 2009. On their income statement the company would use 2008 as the previous year's revenues and 2009 as the current year's revenues. As a hypothetical, Company XYZ had revenues of $400 in 2008 and revenues of $350 in 2009.
Subtract the value from the end of the period from the value from the beginning of the period. In the hypothetical, Company XYZ would subtract $350 from $400, which equals negative $50.
Divide step 2 by the value from the beginning of the period. In the hypothetical, the company would divide the negative $50 from $400, which equals a negative 0.125.
Multiply step 3 by 100 and take the absolute value of the product. In the hypothetical, multiply negative 0.125 by 100, which equals a negative 12.5 percent. The absolute value of negative 12.5 percent is 12.5 percent--simply drop the negative value.