Excel percentage formulas: percent of total, percent change, discounts

In short: percent of total =B2/B8, percent change =(C2-B2)/B2, add 15% =B2*(1+15%), take off 15% =B2*(1-15%). The result is a decimal such as 0.15, and the percent format displays it as 15%.

Try it now

How much of the marketing budget goes to each channel? Enter the formula in C2 and it will be filled down to C7. The practice sheet has no percent format, so you will see decimals: 0.2 stands for 20%.

Task In C2, calculate what share of the total marketing budget in B8 goes to trade fairs. The formula is filled down to C7. The result shows as a decimal here: 0.2 means 20%.

	A	B	C
1	Channel	Cost $	Share
2	Trade fairs	12400
3	Online ads	8600
4	Print ads	15300
5	Newsletter	4200
6	Social media	9800
7	Sponsoring	6700
8	Total	57000

0.15 versus 15%: how Excel stores percentages

A percentage in Excel is just a way of displaying a number. The cell always holds the decimal: 15% is 0.15, 100% is 1 and 120% is 1.2. The percent format multiplies by 100 for display and adds the % sign, but the underlying value does not change.

• Type 15% into an empty cell and Excel stores 0.15 and applies the percent format for you.
• Apply the percent format to a cell that already contains 15 and you get 1500%, because the value really is 15, not 0.15.
• The format sits under Home > Number as the % button, or press Ctrl+Shift+%. Use Increase Decimal to show 21.8% instead of 22%.
• You can use the % sign inside formulas: =B2*8% is the same as =B2*0.08.

So the one rule to remember: do not multiply by 100 on top. =B2/B8*100 returns 21.75, and with the percent format applied that shows as 2175%.

The percentage formulas you will actually use

Question	Formula	Example
Percent of total	=part/total	=B2/$B$8: 12,400 of 57,000 is 21.8%
X percent of a number	=number*percent	=B2*20%: a 20% tip on 45 is 9
Percent change	=(new-old)/old	=(C2-B2)/B2: 48,000 to 52,800 is 10%
Increase by a percentage	=value*(1+rate)	=B2*(1+8%): 100 plus 8% sales tax is 108
Decrease by a percentage	=value*(1-rate)	=B2*(1-15%): 200 with 15% off is 170
Original value before an increase	=value/(1+rate)	=B2/(1+8%): 108 including tax is 100 before tax

For percent of total, every row divides by the same total cell, so that cell needs dollar signs before you fill the formula down. The absolute references lesson covers why. The total itself usually comes from SUM.

Percent change between two numbers

"By what percentage did sales grow?" always comes down to the same calculation: the difference divided by the old value. A negative result is a decrease. Try it with two years of sales figures.

Task In D2, calculate the percent change in sales from 2025 to 2026. The formula is filled down to D7. The result shows as a decimal: 0.1 means up 10%, -0.07 means down 7%.

	A	B	C	D
1	Product group	Sales 2025 $	Sales 2026 $	Change
2	Printer paper	48000	52800
3	Toner	31500	29295
4	Binders	22800	26220
5	Office chairs	56000	56000
6	Desks	17400	18792
7	Monitors	39900	35910

=C2/B2-1 is a shorter way to write the same thing. If the old value is 0, a percent change is not defined and Excel shows #DIV/0!.

Adding tax, taking off a discount

For prices, think in factors. Adding 8% means multiplying by 1.08, taking 15% off means multiplying by 0.85. Keep the rate in its own cell and write =B2*(1+B3) or =B2*(1-B3), so a new rate only has to be typed once. When there are several steps, chain the factors.

Task The supplier takes the discount in B3 off the list price. Tax from B4 is then added to the discounted price. In B6, calculate the final price. Discount and tax rate are shown as decimals: 0.15 is 15%.

	A	B
1	Quote: conference table
2	List price net $	1240
3	Discount	0.15
4	Tax rate	0.19
5
6	Final price incl. tax $

Common mistakes

Multiplying by 100 and using the percent format

Pick one. Either multiply by 100 and keep a plain number format, or skip the 100 and let the percent format do the work. Doing both inflates every value a hundredfold.

Dividing by the wrong number

Percent change is always relative to the starting value. Going from 80 to 100 is up 25%, while going from 100 to 80 is down 20%. Divide by the new value and the numbers are wrong.

Missing parentheses

=C2-B2/B2 works out as C2 minus 1, because Excel divides before it subtracts. Wrap the difference in parentheses.

Removing tax by subtracting the rate

108 minus 8% is 99.36, not 100. Tax was added on the pre-tax price, so you have to divide: =B2/(1+8%).

Percent versus percentage points

If a conversion rate moves from 20% to 25%, it rose by 5 percentage points, which is 25% growth. =C2-B2 gives the change in points, =(C2-B2)/B2 the relative change.

Percentages in German Excel

Percentage math needs no functions, so the formulas look the same in a German Excel. What changes is the decimal separator: German Excel writes 0,15 where you would write 0.15, and arguments in functions are separated by semicolons. The % sign works everywhere. A few German terms you may run into:

English	German
Percent Style	Prozentformat
percent of total	Anteil in Prozent
percent change	prozentuale Veränderung
percentage points	Prozentpunkte
discount, VAT	Rabatt, Mehrwertsteuer (MwSt.)
SUM, ROUND	SUMME, RUNDEN

Which Excel versions support this?

All of them. Basic arithmetic, the % sign in formulas and the percent format work in every version of Excel for Windows and Mac, in Excel for the web and in the mobile apps. Google Sheets and LibreOffice Calc handle percentages the same way.

Frequently asked questions