Add Percentage in Google Sheets: Formulas and Formatting

To display a value as a percentage in Google Sheets, select the cell and choose Format > Number > Percent. To increase a number by a percentage, use a formula such as =A2*(1+B2), where A2 contains the original amount and B2 contains the percentage increase.

What adding a percentage can mean

People use “add percentage” to mean two different things in a spreadsheet. One is formatting a number so it appears with a percent sign. The other is doing arithmetic: increasing an amount by a percentage, such as adding 15% to a price. These operations are related, but the formatting command does not change the underlying value or calculate an increase.

For example, formatting the number 0.15 as a percentage displays 15%. Formatting the number 15 displays 1,500%, because percentages are shown as the underlying number multiplied by 100. If you want to calculate a 15% increase on an amount of 80, the result is 92—not 80.15 and not 15% of 80 alone. Keeping these distinctions in mind prevents many spreadsheet errors.

Format a value as a percentage

In Google Sheets in a web browser, select one or more cells, then choose Format > Number > Percent. You can also use the percent (%) button in the toolbar. The cell’s stored number stays the same; only its display changes. For example, a cell containing 0.25 will display as 25% after percentage formatting.

To enter a percentage directly, type it with the percent sign, such as 15%, and press Enter. Sheets interprets that as the numeric value 0.15 and displays 15%. If you type 15 and then apply percentage formatting, Sheets displays 1,500%. To make that value display as 15%, enter 0.15 or enter 15% directly.

For more control over how many digits appear after the decimal point, select the formatted cell and use the toolbar’s decimal-place controls. For example, 0.156 can display as 15.6% or, with no decimal places, 16%. The underlying value remains 0.156 in either case; the second display rounds what you see, rather than changing the stored value.

Increase an amount by a percentage

To add a percentage increase to an original amount, multiply the amount by one plus the percentage. This keeps the calculation clear and works whether the percentage is typed directly into the formula or stored in a separate cell.

With an original amount in A2 and a percentage increase in B2, where B2 contains 15%, enter =A2*(1+B2) in C2. If A2 is 80 and B2 is 15%, the formula returns 92: 80 multiplied by 1.15. Format C2 as currency or an appropriate number format if you want the result to display as a price.

If you prefer to put the percentage directly in the formula, with the original amount in A2, use =A2*(1+15%). With A2 equal to 80, the result is also 92. A cell reference is more flexible when you plan to change the rate or apply different rates to different rows. Copying the formula down will adjust relative references, so A3 and B3 are used in the next row.

Calculate the percentage amount or a decrease

Sometimes the goal is to find the percentage amount by itself, without adding it to the original. With the original amount in A2 and the rate in B2, where B2 is 15%, enter =A2*B2 in C2. For an amount of 80, the result is 12. To get the increased total, add that 12 to 80, or use the increase formula from the previous section.

To reduce an amount by a percentage, multiply it by one minus the rate. With the starting amount in A2 and the percentage decrease in B2, enter =A2*(1-B2) in C2. If A2 is 80 and B2 is 15%, the result is 68. The percentage amount removed is 12, and 80 minus 12 equals 68.

For a direct calculation without a percentage cell, with the original amount in A2, enter =A2*(1-15%). If A2 contains 80, the result is 68. These formulas assume the rate is a percentage such as 15%, not the whole number 15. If a rate is stored as 15 and means 15%, convert it to 0.15 or divide it by 100 before using it as a rate.

Add percentage points instead of a percentage increase

A percentage increase and a percentage-point increase are not the same. If a rate rises from 10% to 12%, it has increased by 2 percentage points. The relative increase is 20%, because the 2-point change is 20% of the original 10% rate. Which calculation is appropriate depends on what the figures represent.

With an initial rate in A2 and a change in percentage points in B2, enter =A2+B2 in C2. If A2 is 10% and B2 is 2%, the result is 12%. Here, B2 holds the two-percentage-point change as a percentage-formatted value, equivalent to 0.02. Do not use the percentage-increase formula for this situation unless the change is intended to be relative to the original rate.

Find what percentage one value is of another

Another common task is expressing a part as a percentage of a total. Divide the part by the total, then format the result as a percentage. With a part in B2 and a total in C2, enter =B2/C2 in D2. If B2 is 30 and C2 is 120, the result is 0.25, which displays as 25% when D2 is formatted as a percentage.

For a column of items compared with one shared total, use an absolute reference for the total so it stays fixed when you copy the formula. With item amounts in B2:B6 and the total in B7, enter =B2/$B$7 in C2, format C2 as a percentage, and fill the formula down through C6. If B2 is 30 and B7 is 120, C2 displays 25%. The dollar signs lock the reference to B7 while the item reference changes by row.

If the total can be zero or blank, a division formula may show an error. You can leave the result blank in those cases by using an IF check. With the part in B2 and total in C2, enter =IF(C2=0,"",B2/C2) in D2. This returns a blank when C2 is zero and otherwise returns the part divided by the total. Format D2 as a percentage to show the result in percent form.

Common percentage mistakes and how to fix them

The result is 1,500% instead of 15%: The cell likely contains 15 rather than 0.15. Enter 15% or 0.15 if the intended rate is 15%.
The increase is too small: Check whether the rate cell contains 15% or the number 15. Multiplying by 15 treats it as fifteen times the original, not a 15% rate.
The result shows too many or too few decimals: Adjust the displayed decimal places. This changes the appearance, not the stored calculation.
A copied formula uses the wrong total: Lock a shared total reference with dollar signs, as in $B$7, before filling the formula down.
A percentage of zero shows an error: Check whether the denominator is zero or blank, and decide whether to show a blank, a zero, or a message for that case.

A useful check is to calculate the change separately. For an 80 amount increased by 15%, the increase is 12 and the new total is 92. If your formula returns 12 when you expected 92, it calculated only the percentage amount. If it returns 1,280, the rate may have been entered as 15 instead of 15%.

Choosing a display format for results

Choose a format that matches what the result means. A rate, share, or growth percentage should generally display as a percentage. A price after a percentage increase should normally display as a currency or number, not as a percentage. Formatting an amount like 92 as a percentage would display 9,200%, even if 92 is a perfectly correct result for a price calculation.

Percentage formatting is useful for reports because it makes rates easier to scan, but remember that rounding can conceal small differences. For example, 12.4% and 12.49% both display as 12% with no decimal places. Increase the displayed precision when readers need to compare close values. Google Sheets also lets you choose other number formats through Format > Number; the right option depends on whether a cell represents a rate, money, a count, or another quantity.

Excel has similar percentage formatting and broadly similar formulas, but this guide’s menu path and toolbar instructions are for Google Sheets in a web browser. In either program, formatting is separate from the calculation: a percent sign in the display does not by itself add a percentage to another value.

Frequently Asked Questions

How do I add 10% to a number in Google Sheets?

With the number in A2, enter =A2*(1+10%) in another cell. If A2 is 100, the result is 110. You can instead store 10% in B2 and use =A2*(1+B2), which is easier to update.

How do I add a percent sign without changing the value?

Select the cell and choose Format > Number > Percent, or click the percent button in the toolbar. This changes the display, not the underlying value. For instance, 0.5 will display as 50%.

Why does Google Sheets turn 15 into 1,500%?

Percentage formatting displays a value multiplied by 100. The number 15 therefore appears as 1,500%. Enter 15% or 0.15 if you mean fifteen percent.

How do I calculate a 20% discount?

With the original price in A2, enter =A2*(1-20%). If the price is 50, the result is 40. If you need the discount amount alone, use =A2*20%, which returns 10 for a price of 50.

How do I calculate the percentage change between two values?

With the original value in A2 and the new value in B2, enter =(B2-A2)/A2 in C2 and format C2 as a percentage. If the original is 80 and the new value is 92, the result is 15%. This calculation assumes the original value is not zero.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

More in How-to basics

Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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