Percentage change shows how much a value increased or decreased relative to where it started. The formula is short, but formatting, zero values, and negative starting values are where mistakes usually happen.
Does this affect you?
Use this for Excel for Microsoft 365, Excel 2021, Excel 2019, or Google Sheets when comparing old versus new values such as sales, prices, traffic, weight, or monthly totals.
Calculate basic percentage change
Use the old value as the base.
- Click an empty cell.
- Type =(B2-A2)/A2, where A2 is the old value and B2 is the new value.
- Press Enter.
- Select the result and click Percent Style on the Home tab.
- Use Increase Decimal if you need values such as 15.3 percent.
A positive result means the number increased. A negative result means it decreased.
Handle zero or negative starting values
These two cases need extra care.
- If the old value is zero, the formula divides by zero and returns #DIV/0!. Use =IFERROR((B2-A2)/A2,”N/A”) to show a cleaner result.
- If the old value is negative, the sign can look counterintuitive. Use =(B2-A2)/ABS(A2) when you want the change measured against the size of the old value.
- With negative numbers, compare the result against the real-world direction of the change to make sure the sign communicates what you intend.
More control
Add visual cues
Use Home > Conditional Formatting > Color Scales or Icon Sets to highlight growth, decline, and outliers in a percentage-change column.
Build month-to-month formulas
For period-over-period change, compare each row with the previous one: =(B3-B2)/B2, then =(B4-B3)/B3, and so on.
Do not confuse percent change with percentage points
Moving from 20 percent to 25 percent is a 25 percent relative increase, but a 5 percentage-point increase. Reports should name the right one.
Round display without changing the value
Use Increase or Decrease Decimal to change what you see while keeping the full calculated value for later formulas.
Sources
- Microsoft Support – Calculate the percentage of change between two numbers (2025)
- Microsoft Support – Show numbers as percentages (2025)
- Microsoft Support – Highlight cells with conditional formatting (2025)