Calculate Percentage Change in Excel and Label It Clearly
On this page
Percentage change compares a difference with a starting value. It is not the same as subtracting two percentages or dividing by the final value. Keeping the baseline visible prevents many misleading reports.
Practice setup: Start in a new workbook with fictional data. Formulas use English function names and commas; your regional settings may require semicolons. Interface labels vary between Excel versions. Keep the source data and check your results before reusing the method.
Enter before-and-after values
Use Item, Before, After and Change in A1:D4. Add Notebook 100 and 120, Pen 80 and 60, and Folder 50 and 50. All amounts use the same fictional unit.
In D2 enter =(C2-B2)/B2, fill down and apply a percentage format. The results are 20%, -25% and 0%. The numerator is the difference; the denominator is the original amount.
Explain the denominator
Notebook rises by 20 from 100, giving 20%. Pen falls by 20 from 80, giving a 25% decline. The same absolute change has a different relative size because the starting values differ.
Dividing by After answers a different question. (120-100)/120 is about 16.67%, not the standard increase from 100 to 120. Write the comparison in words before building the formula.
Understand reversed changes
Going from 100 to 120 is a 20% increase. Returning from 120 to 100 is about a 16.67% decline because 120 is now the baseline. The percentages are not equal in size even though the amount returns to its starting point.
Use a heading such as Change from previous period, with the relevant periods shown. A vague heading such as Growth can conceal the baseline or imply that every value is positive.
Distinguish percentage points
A rate moving from 10% to 15% rises by 5 percentage points. Its relative increase is 50%, calculated as (15%-10%)/10%. These are different measures, and both can be useful when labelled correctly.
A percentage number format does not explain which measure you calculated. Use separate headings and a short definition if the report includes both.
Treat a zero baseline honestly
The usual formula divides by zero when Before is 0. A move from 0 to 20 does not have a defined finite percentage increase under this formula. Show No baseline rather than replacing the error with 0%.
For a practice display, use =IF(B2=0,"No baseline",(C2-B2)/B2). Missing or negative baselines can need additional reporting definitions. Do not assume one formula describes every business situation.
Check before charting
Test an increase, decline and unchanged case. Reverse-check the first example with =100*(1+20%), which should give 120. Keep raw amounts beside percentages because a 100% increase from 1 to 2 has a different practical size from 1000 to 2000.
Try it yourself
An amount moves from 200 to 250, then back to 200. Calculate both changes and explain why they differ.
Check your answer
The increase is (250-200)/200, or 25%. The return is (200-250)/250, or -20%.
The second baseline is larger. Returning to the same amount does not require equal positive and negative percentage changes. Always identify the starting value for each comparison.
Keep exploring: Excel learning path.