When to Use the Percent Sign in a Sentence (The Ultimate Guide)

Do you know what percentage of style guides agree on when to use the percent sign in a sentence? Zero!

To understand when to use the percent sign instead of the word percent, we need to look at the recommendations provided by all four of our primary style guides:

The Chicago Manual of Style (Chicago style)

The Associated Press Stylebook (AP style)

Publication Manual of the American Psychological Association (APA style)

MLA Handbook from the Modern Language Association (MLA style)

Note that The Chicago Manual of Style is the default guide for the publishing industry, so strongly consider following Chicago style if you don’t have a designated guide. For additional information about each guide, visit “Which Style Guide Is Best for You?”

Before we begin, here are several tips for writing the percent sign regardless of which style guide you follow.

Four Tips for Writing the Percent Sign in a Sentence

1. Don’t include a space between the percent sign and the numeral.

Not-so-good: 15 %

Good: 15%

2. Rewrite sentences that start with a numeral and percent sign or add an introductory word or phrase so that the numeral–percent sign combination doesn’t appear at the beginning.

Not-so-good: 17% of the inventory was moldy.

Good: Unfortunately, 17% of the inventory was moldy.

3. Only use the percent sign with numerals, not spelled-out numbers.

Not-so-good: Over thirty-seven% of the county fair tickets were sold before opening day.

Good: Over 37% of the county fair tickets were sold before opening day.

4. Always pair the percent sign with a numeral; don’t use the percent sign as a standalone abbreviation for the noun percentage.

Not-so-good: Only a small % of voters requested mail-in ballots.

Good: Only a small percentage of voters requested mail-in ballots.

When to Use the Percent Sign according to Chicago Style

The Chicago Manual of Style (Chicago style) has separate recommendations for nontechnical and technical content.

For nontechnical content, Chicago style suggests using numerals and the word percent instead of the percent sign. However, if the number falls at the beginning of the sentence, it should be spelled out rather than written as a numeral.¹

The survey showed that only 9 percent of employees liked the company’s new cafeteria food.

Twenty-seven percent of the art students preferred pastels to colored pencils.

For technical content, Chicago style suggests using numerals with the percent sign. But, use the word percent if the number appears at the start of the sentence with a spelled-out number. ²

Of the 500 cats in the study, 17% refused to play with the research toys.

Ninety-five percent of the native trees and 75% of the feed crops survived the drought.

When to Use the Percent Sign according to AP Style

The Associated Press Stylebook (AP style) recently updated its recommendations for using percent signs. Previously, AP style used the word percent with numerals.³ Now, AP style uses the percent sign with numerals in formal content.⁴

The charity drive collected 33% more donations this year.

If you are referring to a percent generically or casually, AP style suggests spelling out the number and using the word percent.⁵

Bob said, “I thought I had about a one percent chance of finding my lost wedding band. But here it is.”

AP style doesn’t directly address the issue of a percent appearing at the start of a sentence. However, it recommends spelling out numbers at the start of sentences,⁶ so those who follow AP style should use the word percent, instead of the sign, in those instances—until the Associated Press tells us otherwise.

When to Use the Percent Sign according to APA Style

The Publication Manual of the American Psychological Association (APA style) recommends using numerals with the percent sign within a sentence.⁷

The grocery store saw a 42% increase in ice cream sales in July.

APA style also recommends using the word percent with spelled-out numbers at the start of a sentence.⁸

Fifty-three percent of the moviegoers ate popcorn; 7% ate smuggled-in candy.

When to Use the Percent Sign according to MLA Style

The MLA Handbook doesn’t comment on percent signs directly. However, the MLA Style Center, which is the official website of MLA Style, published guidelines stating that the word percent should be used with spelled-out numbers in general writing.⁹ (Note that MLA style generally recommends spelling out all numbers that can be written in less than three words.¹⁰)

The professor was disappointed that only seventy-five percent of the class finished the assignment.

In number-heavy documents, the MLA Style Center recommends using numerals with the percent sign (although presumably not at the start of a sentence).

After training, 83% of the shelter dogs could follow sit and stay commands.

A word of caution: While the MLA Handbook is silent on the percent sign, it does say that numerals should always be used with symbols (such as $) and abbreviations (such as lb.).¹¹ MLA style followers who are unfamiliar with the MLA Style Center online guidelines cited above may interpret this to mean that numerals should always be used with the percent sign. Because the guidelines are not in the handbook itself, this interpretation is understandable. I hope the Modern Language Association will clarify this issue in the next edition of the handbook.

Further Reading: Three Tips for Starting a Sentence with a Number

References

1. The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 9.18.
2. The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 9.18.
3. The Associated Press Stylebook 2018 (New York: Associated Press, 2018), 221.
4. The Associated Press Stylebook 2019 (New York: Associated Press, 2019), 218–19.
5. The Associated Press Stylebook 2019 (New York: Associated Press, 2019), 218­–19.
6. The Associated Press Stylebook 2019 (New York: Associated Press, 2019), 206.
7. Publication Manual of the American Psychological Association, 6th ed. (Washington, DC: American Psychological Association), 4.45.
8. Publication Manual of the American Psychological Association, 6th ed. (Washington, DC: American Psychological Association), 4.32.
9. “How do I style percentages?” Ask the MLA, The MLA Style Center, published November 14, 2018.
10. MLA Handbook, 8th ed. (New York: Modern Language Association of America, 2016), 1.4.1.
11. MLA Handbook, 8th ed. (New York: Modern Language Association of America, 2016), 1.4.1.