How to Calculate Percentage in Excel — Formulas for Every Case

Excel is arguably the single best tool ever built for percentage math — once you understand its one crucial quirk. Nearly every confusion people hit ("why did my formula give 0.25 instead of 25?") traces back to the same root cause: Excel stores percentages as decimals, and only displays them with a % sign. Master that one idea, and every formula below will snap into focus.

This guide walks through the exact formulas for the most common percentage tasks, from finding a percent of a number to percent change and symmetric percent difference — with cell references and realistic numbers throughout.

The golden rule: Excel stores percents as decimals

When you type 10% into a cell, Excel doesn't actually store "10". It stores the number 0.10 and slaps a % format on it. A percentage is just a number formatted to show the percent symbol.

This is why the arithmetic "just works": you're always multiplying by the decimal (0.10, 0.25, 0.05), never by 100. It's also why multiplying a cell by 100 can produce confusingly huge-looking results — the % belongs in the formatting, not the formula.

Percentage of a number

To find 15% of 200, put the base value in A1 and the percent in B1:

=A1*B1

With A1 = 200 and B1 = 15% (stored as 0.15), the result is 30. The equivalent hard-coded version is =200*0.15. Both are correct; the cell-reference version is easier to reuse.

Percent increase (from old to new)

Going from 80 to 100 is a 25% increase. The formula:

=(B1-A1)/A1

With A1 = 80 and B1 = 100:

(100 - 80) / 80 = 0.25  →  format as % → 25%

The key subtlety: divide by the old value, not the new one. The increase is relative to where you started.

Need the new value after a rise instead? =A1*(1+25%) grows a starting value of ₹20,000 to ₹25,000.

Percentage change (old vs new)

Percent change uses the same pattern as increase, but the sign does the work. A value that falls from 120 to 90:

=(B1-A1)/A1

(90 - 120) / 120 = -0.25  →  -25%

A negative result means a decrease. This is the all-purpose "how much did it change by?" formula, whether the change is up or down.

Percentage difference (symmetric comparison)

Percent difference is a different animal: it compares two values symmetrically, treating neither as the "old" base. It's used when you want to know how far apart two numbers are without designating a reference:

=ABS(B1-A1)/AVERAGE(A1,B1)

For 80 and 100:

ABS(20) / 90 = 22.2%

Percent change says "25% more than 80," while percent difference says "they differ by 22.2% of their average." Same pair of numbers, different question, different answer — choose deliberately.

Percentage of a total (what percent of)

What percent is 30 of 200?

=30/200

Format as a percentage → 15%. Or with references: =A1/B1 where A1 holds the part and B1 the whole. This is your "share of total" workhorse — survey results, budget breakdowns, anything expressed as part of a whole.

Percent off / discount price

A 25% discount on ₹2,000:

=A1*(1-25%)

Result: 1,500. The (1-25%) factor is just 0.75, multiplying the price down by a quarter. To see the discount amount itself: =A1*25% → 500.

Worked spreadsheet

Purpose	Formula	Example	Result
Percent of a number	=A1*B1	200, 15%	30
Percent increase	=(B1-A1)/A1	80 → 100	25%
Percent change	=(B1-A1)/A1	120 → 90	-25%
Percent difference	=ABS(B1-A1)/AVERAGE(A1,B1)	80 vs 100	22.2%
Part of total	=A1/B1	30 of 200	15%
Percent off	=A1*(1-25%)	2000, 25%	1500

Formatting a cell as a percentage

To get the % symbol to show, select the result cell and apply Percent number format (Ctrl+Shift+% on Windows, or the % button on the ribbon). Formatting multiplies the display by 100 and appends the sign — the underlying value stays a decimal, which is what keeps your formulas correct.

Common mistakes

• Multiplying by 100 in the formula. =0.25*100 gives 25, not 25%. Let the cell formatting add the % — don't hard-code the ×100.
• Dividing by the wrong reference. Increase is always relative to the starting value: (new-old)/old, never /new.
• Confusing change with difference. Change is relative to one base value; difference is relative to the average of both. Use =ABS(B1-A1)/AVERAGE(A1,B1) only when you want the symmetric view.
• Forgetting the percent format. A raw 0.25 in a plain cell is easily misread; format it so the intent is obvious.

Key takeaways

• Excel stores percents as decimals; formatting adds the % sign.
• =A1*B1 finds a percent of a number; =(B1-A1)/A1 finds change from old to new.
• Use =ABS(B1-A1)/AVERAGE(A1,B1) for symmetric percent difference.
• Don't multiply by 100 in formulas — apply percent formatting instead.

FAQ

Why does my formula show 0.25 and not 25%? Because the cell isn't formatted as a percentage. Apply the % number format and it will display as 25% while keeping the correct underlying value.

How do I calculate a percentage of a total in Excel? Divide the part by the whole (=A1/B1), then format the result as a percentage.

What's the difference between percent change and percent difference? Percent change divides by one designated "old" value; percent difference divides by the average of both, treating the values symmetrically.

Should I multiply by 100 in my formula? No. Excel's percent formatting handles the ×100 automatically. Multiplying manually leads to double-counting errors.

Prefer a browser over a spreadsheet? Try the Percentage Calculator, Percentage Increase Calculator or Percentage Difference Calculator — instant results, no cell references required.