percent or %

In this post I discuss when to spell out percent and when to use the % symbol.

In general, use this format: a numeral followed by the word percent.

The unemployment rate remained at 7.3 percent.
The cost of a New York cab ride rose by 17 percent on Tuesday.

Use the % symbol in a scientific document or if your writing contains a lot of statistics. So, in the following paragraph it is appropriate to use %.

As Quebeckers began voting across the province, a Forum Research poll has the PQ capturing 36% of the vote, giving the party a large lead over the Liberals, who have jumped to second place with 29%. The Coalition Avenir Quebec (CAQ) follow with 25%, the Québec solidaire at 6%, with other parties capturing 3%.

(As an aside, if you’re an editor, you will want to check the math and make sure we do not end up with more than 100%. In this example, the total comes to 99% (36+29+25+6+3) so you might want to ask the author why it’s not 100%. Is the missing 1% undecided?)

Note that there is no space between the numeral and the % symbol:

not: 100 %

Note also that whether you use the word percent or the % symbol, you always use a numeral:

100% or 100 percent
not: one hundred % or one hundred percent

Finally, do not confuse the word percent with percentage, which is a general term similar to amount or number. Note also the expression percentage points.

Percentage of popular vote, by party. (heading for a table)
That percentage would have increased to 20% by 2020.
Air Canada said it had a record load factor of 87.9%, up 0.2 percentage points from 2011.

This post is based on The Chicago Manual of Style (15th ed.), paragraphs 9.18–9.20.

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