How to Calculate Percentage Change in Microsoft Excel (Increase and Decrease)

Calculating the percentage change between two numbers is one of the most fundamental financial, analytical, and operational tasks in Microsoft Excel. Whether tracking quarterly sales growth, evaluating year-over-year expense fluctuations, or monitoring website traffic changes, calculating the percentage variance highlights trends that absolute dollar or unit figures cannot reveal. Excel does not feature a dedicated “PERCENTCHANGE” formula, but you can calculate both increases and decreases accurately using standard mathematical syntax and cell formatting.

The Core Formula for Percentage Change

In mathematics and finance, percentage change represents the difference between a new value and an old value, expressed as a proportion of the original baseline:

Percentage Change = (New Value – Old Value) / Old Value

Alternatively, the formula can be simplified algebraically as:

Percentage Change = (New Value / Old Value) – 1

Both mathematical variations yield identical results in Excel. Here is how to apply them across your spreadsheets:

1. Open your spreadsheet in Microsoft Excel. Assume cell A2 contains your original baseline value (e.g., 2025 Revenue: £50,000) and cell B2 contains your updated value (e.g., 2026 Revenue: £65,000).
2. Select cell C2 where you want the percentage change to appear.
3. Enter either of the following formulas into the formula bar:
   • =(B2-A2)/A2
   • =(B2/A2)-1
4. Press Enter. Initially, Excel will display the raw decimal value (e.g., 0.3).
5. With cell C2 selected, go to the Home tab on the Excel ribbon.
6. In the Number group, click the Percent Style icon (%), or press Ctrl + Shift + % (Windows) / Cmd + Shift + % (macOS).
7. Use the Increase Decimal button to display one or two decimal places as needed (e.g., 30.00%).
8. Hover over the bottom-right corner of cell C2 until the cursor turns into a black plus icon (the fill handle), then drag down to calculate the percentage change for remaining rows.

Handling Decreases and Negative Percentage Changes

The standard formula handles negative growth automatically. If the new value in cell B2 is lower than the baseline in cell A2 (for instance, expenses dropping from £20,000 to £15,000):

• =(15000-20000)/20000 evaluates to -0.25, which formats as -25.00%.
• To distinguish positive gains from negative declines visually, apply custom accounting formatting. Select your percentage column, press Ctrl + 1 to open Format Cells, choose Custom, and enter:
  +0.0%;[Red]-0.0%;0.0%
  This rule automatically prefixes positive figures with a plus sign, formats negative variances in red text with a minus sign, and displays neutral zeroes cleanly.

Preventing the #DIV/0! Error on Zero Baselines

If your baseline period (cell A2) contains a zero or is blank, dividing by zero will cause Excel to output a jarring #DIV/0! error across your tables. To keep your dashboards clean and professional, wrap the calculation inside the IFERROR or IF function:

=IFERROR((B2-A2)/A2, 0)

Or, if you want a custom text note indicating that the baseline is new or undefined:

=IF(A2=0, "New Metric", (B2-A2)/A2)

Handling Calculations Involving Negative Baselines

When financial metrics switch from a negative net loss to a positive net profit (for example, moving from -£10,000 to +£5,000), the standard formula produces mathematically misleading results because dividing by a negative number reverses the direction of the sign. To ensure that an increase from a negative number always shows as a positive percentage growth, wrap the denominator in the ABS (absolute value) function:

=(B2-A2)/ABS(A2)

With an original baseline of -10,000 and a new figure of +5,000: (5000 - (-10000)) / ABS(-10000) = 15000 / 10000 = +150%, accurately reflecting a positive financial turnaround.