How to Calculate Percentage Change in Excel

Use the standard percentage-change formula

Percentage change is new minus old, divided by old. In Excel, =(B2-A2)/A2 returns the decimal change from A2 to B2. If sales rise from 80 to 100, the result is 0.25, displayed as 25% after applying Home > Percent Style (Ctrl+Shift+%) or a Percentage number format.

Do not multiply the formula by 100 and also apply Percentage format; that displays 2,500% instead of 25%. Store the decimal and let formatting control its appearance. If the stored value itself must be rounded, wrap it, for example =ROUND((B2-A2)/A2,3); otherwise keep the full precision and round only the display.

To compare every period with the first one instead of the previous one, anchor the baseline: =(B3-$B$2)/$B$2 fills down against B2. To compare with the previous period, keep the baseline relative so each row looks one row up. Choose the version that matches the question, and say which one the column shows in its header.

Percentage change, percentage points, and share

If a rate moves from 20% to 25%, the relative increase is (25%-20%)/20%=25%, while the percentage-point change is 25%-20%=5 percentage points. These answer different questions, so label the result explicitly.

Percent of total is a third idea: =B2/SUM($B$2:$B$10) describes share, not change. A clear header such as Change vs prior month, Percentage points, or Share of total prevents formulas that are individually correct from being misread.

Handle zero and negative baselines deliberately

When the old value is zero, ordinary percentage change is undefined and Excel returns #DIV/0!. =IF(A2=0,"N/A",(B2-A2)/A2) communicates that limitation. Returning 0 would falsely claim no change. Decide whether a new activity should instead be labeled New according to your reporting policy.

Negative starting values flip the sign of the standard formula: moving from -100 to -50 is an improvement, yet =(B2-A2)/A2 returns -50%. One common convention is =(B2-A2)/ABS(A2), which returns +50%. It is a convention, not a universal rule, so state it beside the metric; finance reports may prefer absolute change instead.

Common mistakes

Reversing old and new changes both the sign and the denominator, and dividing by the new value answers a different question. Blank cells are treated as zero in arithmetic, and numbers stored as text can cause errors. Keep the absolute change =B2-A2 beside the percentage when scale matters: a 100% increase from 1 to 2 is large in percentage terms but small in practice.