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.

Image courtesy of FreeDigitalPhotos

Numbers: Numerals or words?

Numbers can be expressed either as numerals (539; 4.49; 3,689) or as words (four, seventeen).* When do you use which?

Here are the general rules†:

1) spell out the numbers one through hundred

2) spell out round numbers with hundreds, thousands, hundred thousands, millions

So you would use:

seventy-eight; 3,589; 762; three million

However, percentages always take numerals:

25% or 25 percent
not: twenty-five percent or twenty-five %

(Note that there is no space in 25%.)

In fact, abbreviations always take numerals:

47¢ (and not .47¢—unless of course you really mean less than half a cent!)

On the other hand, numbers with centuries are always spelled out:

the twenty-first century
not: the 21st century

Finally, there’s a third general rule that’s often flouted:

3) don’t begin a sentence with a numeral

Thus, you will want to avoid something like this:

97 Tips for Canadian Real Estate Investors is a national bestseller.

You could change this to:

Ninety-seven Tips for Canadian Real Estate Investors is a national bestseller.

Another solution (which avoids tampering with the actual title of the book) is to recast the sentence so it doesn’t start with the number:

Don Campbell’s 97 Tips for Canadian Real Estate Investors is a national bestseller.

Following these three simple rules will help you steer clear of 90 percent of the potholes with numbers!

*I am using the word numeral in the restricted sense that the Chicago Manual of Style uses it as non-spelled out forms. Other references (like the Canadian Oxford Dictionary) use the word numeral to refer to both the spelled out and non-spelled out forms.

†taken from the Chicago Manual of Style chapter 9

Image at top courtesy of scottchan.