Percent Change & % of Total

Excel Formulas › Percentage

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Two everyday percentage jobs: percent change (how much did this grow over last period?) and percent of total (what share is this of the whole?). Both are simple ratios — the trick is anchoring and formatting them correctly.

Quick formula: for an old value in A2 and a new value in B2:
=(B2 - A2) / A2
Format the cell as a percentage. A result of 0.25 displays as 25% growth; a negative result is a decline.

Functions used (tap for the full reference guide):

SUMIFERROR

The example

Last month vs this month, with the percent change in column C.

ABC
1LastThisChange
2$200$250+25%
3$400$300-25%
4$120$180+50%

The formula

Percent change in C2, formatted as a percentage:

=(B2 - A2) / A2 // (250-200)/200 = 0.25 → 25%

How it works

Percent change is always “difference over the starting value”:

  1. B2 - A2 is the raw change — how much it moved (+50 here).
  2. Dividing by the original value A2 expresses that move relative to where it started: 50/200 = 0.25.
  3. Format the cell as Percentage (Ctrl+Shift+%) so 0.25 shows as 25%. Don’t multiply by 100 yourself — the format does it.
  4. A negative result is a decline; the sign takes care of itself.

% of total is the other common one. Divide each value by the grand total, locking the total: =B2/SUM($B$2:$B$8). Format as a percentage and the column sums to 100%.

Try it: interactive demo

Live demo

Set an old and new value; see the percent change.

Percent change:

Variations

Percent of total

Each value’s share of the grand total (lock the total):

=B2 / SUM($B$2:$B$8)

Guard against divide-by-zero

A starting value of 0 makes percent change error. Wrap it:

=IFERROR((B2 - A2) / A2, "n/a")

Increase a value by a percentage

Add 8% to a price:

=A2 * (1 + 0.08)

Pitfalls & errors

#DIV/0! The starting value is blank or zero. Wrap in IFERROR, or check the source data.

Don’t multiply by 100. Writing =(B2-A2)/A2*100 and formatting as a percentage gives 2500%. Let the percentage format do the ×100.

Mind which value is the base. Percent change divides by the old value. Dividing by the new value answers a different question.

Practice workbook

📊
Download the free Percent Change & % of Total practice workbook
The two-period table with live percent change, percent of total, divide-by-zero guard, and percentage increase, plus 4 challenges with answers. No sign-up required.

Frequently asked questions

What is the formula for percent change in Excel?
=(new - old) / old, e.g. =(B2-A2)/A2, formatted as a percentage. A result of 0.25 shows as 25% growth and a negative value is a decline.
How do I calculate percent of total?
Divide each value by the grand total with the total locked: =B2/SUM($B$2:$B$8). Format as a percentage and the column will sum to 100%.
Why does my percentage show 2500% instead of 25%?
You multiplied by 100 in the formula and also applied percentage formatting, which multiplies by 100 again. Remove the *100 and let the cell format handle it.

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Related formulas: Rank values (no gaps) · Running total · Sum the top N values

Function references: SUM · IFERROR