=(new_value-old_value)/old_value

If you need to calculate the percentage change between two values in Excel, you can use a formula that divides the change itself by the "old" value. A classic example would be to calculate the percentage between sales last month and sales this month.

How the formula works

In the example, the active cell contains this formula:

=(D6-C6)/C6

In this case, Excel first calculates the difference between the values (the actually change in sales) then divides that result by the original, or "old" value to get the decimal value -0.3435:

=(49500-75400)/75400

=-25900/75400

=-0.3435

Because cell E6 is formatted using the Percentage number format (with no decimals), Excel displays the final result as -34%