GrammarPhile Blog

If you just googled “When to use percent or percentage,” you’ve come to the right place. Here’s what you need to know:

“Percent” and “percentage” are sometimes used interchangeably, especially when people are speaking informally. But these words actually have slightly different meanings (“percent” is one part of a hundred; “percentage” is a part of a whole) and are different parts of speech; “percent” is an adverb and “percentage” is a noun.

The Chicago Manual of Style, 17^th Edition, our preferred style guide (mainly because anything over 1,100 pages must be right), has this to say on the issue:

“Despite changing usage, Chicago continues to regard percent as an adverb (“per, or out of, each hundred,” as in 10 percent of the class)—or, less commonly, an adjective (a 10 percent raise)—and to use percentage as the noun form (a significant percentage of her income). The symbol %, however, may stand for either word.” (3.82)

I’ve had a love affair with words and grammar pretty much my entire life. Math? Not so much. It’s useful, yes. Important too. But having to apply it is like going to the dentist — something I need to do even if I’m less than thrilled about it. So it’s with the greater good in mind that I tackle the use of percent, percentage, percentage points and related questions. You’re welcome.

Percent vs. Percentage

Although some sources (the mercurial Merriam-Webster’s being one of them) suggest that percent and percentage are interchangeable, the more traditional approach is to use percent with a number and percentage with no number:

A surprisingly high percentage of college freshmen drop out.

More than 25 percent of college freshmen drop out.

No style guide that we know of supports using numerals with percentage. For that reason, the following construction is incorrect:

The percentage of college freshmen who drop out is higher than 25.

You’d either need to add “percent” at the end of the sentence or rewrite to avoid using “percentage/percent” in the same sentence. The latter approach is preferable but not always possible, as in sports stories. For example:

Tater and Tot had the highest field goal percentages for the night, shooting 63 and 68 percent, respectively.

Percent vs. Percentage Points