Excel percent change formula: calculate percentage increase / decrease

This tutorial explains how to calculate percentage increase or decrease in Microsoft Excel, handling both positive and negative numbers and zero values. Excel offers several variance functions, but none directly calculate percent difference. This tutorial provides the correct formulas.

Understanding Percentage Change

Percentage change (or percentage variance) shows the proportional change between an original and a new value. It's useful for comparing values across periods (e.g., year-over-year sales).

Excel Formulas for Percentage Change

Two primary formulas exist:

• Classic Formula: (new_value - old_value) / old_value This involves three steps: subtraction, division, and multiplication by 100 (handled automatically by Excel's percentage formatting).

• Simplified Formula: new_value / old_value - 1 This achieves the same result more concisely.

Applying the Formulas in Excel

Let's say estimated sales are in column B and actual sales in column C. Using the simplified formula, the percent change in row 3 would be: =C3/B3-1. Format the cell as a percentage. Drag the formula down for the entire column.

Percent Increase/Decrease

The same formula applies to percent increase or decrease. For example, the percent increase between B2 and C2 is =(C2-B2)/B2 or =C2/B2-1.

Absolute Value of Percentage Change

To get the absolute value (ignoring the sign), use the ABS function: =ABS((C3-B3)/B3) or =ABS(C3/B3-1).

Calculating Discount Percentage

The discount percentage is calculated similarly: (discounted price - regular price) / regular price or discounted price / regular price - 1. Use ABS to display as a positive value.

Calculating Value After Percent Change

To find the new value after a percentage change: initial_value * (1 percent_change). For example, =B2*(1 C2).

Handling Negative Numbers

For negative numbers, modify the denominator to be positive using ABS: (new_value - old_value) / ABS(old_value). This is =(C2-B2)/ABS(B2). Note that this may produce misleading results if the sign changes between old and new values.

Handling #DIV/0! Errors (Zero Values)

The IFERROR function prevents divide-by-zero errors. Several approaches exist:

• Return 0: =IFERROR((C2-B2)/B2, 0)
• Return 100%: =IFERROR((C2-B2)/B2, 1)
• More Robust Solution (Nested IF): =IF(C20, IFERROR((C2-B2)/B2, 1), IFERROR((C2-B2)/B2, 0)) This handles cases where both old and new values are zero.

This comprehensive guide provides the formulas and techniques to accurately calculate percentage change in Excel, addressing various scenarios and potential errors. A practice workbook is available for download (link provided in the original text).

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