The concept of percentage is very similar to fractions. To calculate a percentage we would think of the whole (the denominator in fractions) as a number that can be divided into 100 parts. We then ask ourselves what is the share of the smaller number (the part, not necessarily smaller) in that 100 parts.

Definition of Percentage

1/100 = 1%

Percentage Formula

Percentage formula = (Numerator/Denominator)×100

Or you can think of it as


The way to work on percentage formula in Excel, Google Sheets and Mac Numbers are essentially the same. The sections below provide multiple examples.

Calculate Percentage in Spreadsheets

Percentage Formula Excel

To answer the question “What percentage is 20 out of 30?” you would put in Excel


You can then press Ctrl+Shift+% keyboard shortcut to format the cell as a percentage value.


You can format the cell as Percentage first by going to Home tab, Number group, Percentage symbol.

Then once you put in the equation above, it will convert it into a percentage.

Do not put


to then convert the cell into percentage format, since that will show 6667% instead of the correct value of 67%.

Percentage Formula in Excel Column

To format the whole column in Excel as a percentage, make sure you have the number in decimal format.

That is, you want to firstly divide actual part numbers with actual base number. This will give you decimal numbers.

Select the column, then click on the Percent Style symbol in Home tab Number group.

If you already have the numbers as it should be when it is converted to a percentage, for example, 50, 38, 73 etc, there is a little trick.

Type 100 in a blank cell.

Select the cell, press Ctrl+C to copy.

Select the cells where you want numbers to appear in percentage format.

Press Alt+E+S+I, where the last I is a shortcut to Divide Operation in Paste Special dialogue.

This will convert the numbers to proper decimals.

Format the column as percentage using Percent Style symbol as mentioned before.

Percentage Formula Google Sheets

To calculate the percentage of a number, such as “Calculate x as a percentage of y”, do


You can then convert the cell to a percentage.

The percentage will be shown to two decimal places. However, Google Sheets will use the underlying value instead of the value shown. So if you have say recurring decimals, that is what Google will use, not just the value up to two decimal points.

For example, when we want to know “What is the percentage of visitors that purchase luxurious items in a shopping mall in a particular month?”, we will calculate the total number of consumers that purchased luxurious items in that month (x), and divide it by total number of visitors who frequented the shopping mall in that month.

Percentage Formula in Numbers

Suppose you have income in column B and expense in column C, then to calculate value of expense as a percentage of income, you would type


You then go to Paintbrush>Format>Percentage, click on the cell then choose Fill in the options that pop up.

Drag the cell down to the end of the column.

Percentage Formula in Math

Examples: 25% of 100 is 25

This means if you multiple 25 by 25% you will get 100.

Example: 20% of 200 is 40

This means if you multiple 200 by 20% you will get 40. Alternatively, if you divided 40 by 200, you will get 1/5, or 20%.

Example: 59 is 197% of 30

This means if you multiple 30 by 1.96 repeater, you will get 59.

Percentage Increase

There are many ways to phrase a question, the important thing is to differentiate between “amount of increase” and “actual whole in the beginning”.

Suppose the number of students this year increased by 500 from a student base of 2000 last year, then

part = 500

base = 2000

percentage increase = 500/2000, or 25%.

If the question says the number of students this year increased to 2500 compared to a student number of 2000 last year, then

increase = 2500-2000=500

base = 2000

percentage increase = (2500-2000)/2000, or 25%.

Alternatively, the question might say students numbered 2500 this year, compared to 2000 last year. What is the percentage increase?

increase = 2500-2000=500

base = 2000

percentage increase = (2500-2000)/2000, or 25%.

If you have to do a reverse calculation, you need to divide the new number by 1+x%. Consider the example below:

Tickets sold increased by 25% to 250. What was the number before the increase in sales?

You would do 250/1.25=200, instead of 250/25%=1000, which is wrong.

Percentage Decrease

You can have percentage decrease just as you would have percentage increase. Percentage decrease normally occurs in sales.

However, instead of using

new number – original number

as the numerator, you would use

original number – new number

This is so that you will always get a positive number.

You divide this difference by the original number to get the percentage decrease.

=(original number – new number) ⁄ original number

For example, if sales figure is $8M this year compared to $10M last year, then the percentage decrease is

(10-8)/10*100% = 20%

That is, you would say “sales decreased by 20% this year”.

Percent Difference

The concept “percent difference” is the same as “percentage difference”. The word “percent” normally comes after a concrete number, while you can talk about “percentage” without a number in a sentence.

Suppose you need to calculate the percent of people who volunteers on second day of a festival compared to the first day, see the table below:

Percent Change

See Percentage Increase.

Percent Change Formula

See Percentage Increase and Percentage Decrease.

Related Posts

Pin It on Pinterest

Share This