Less or Fewer?

Q. Hi. My fellow editor and I disagree about the use of “less” and “fewer” when talking about percentages. In the example he asked me about, the first phrase of the sentence said something about a certain number of women who do something, then the following phrase said something like “less than 5%” did something else. My fellow editor says that because the sentence is referring to (multiple) women, the phrase should say “fewer than 5%,” while I believe that because the sentence is talking about a percentage (a single quantity), it should say “less than 5%.” None of our sources is helpful with this question of whether a percentage is a single quantity or a number. Please help straighten us out . . .

A. Let me start with the usage note in The American Heritage Dictionary (CD-ROM, version 4.0, 1995):

Usage Note: The traditional rule holds that fewer is used with expressions denoting things that can be counted (fewer than four players), while less is used with mass terms denoting things of measurable extent ( less paper; less than a gallon of paint). However, less is idiomatic in certain constructions where fewer would occur according to the traditional rule. Less than is used before a plural noun that denotes a measure of time, amount, or distance: less than three weeks; less than $400; less than 50 miles. Less is sometimes used with plural nouns in the expressions no less than (as in No less than 30 of his colleagues signed the letter ) and or less (as in Give your reasons in 25 words or less).

In my opinion, “less than 5 percent” could be added to the list of plural nouns that denote a measure of time, amount, or distance—where 5 percent is analogous to $400. A big reason I would say this is that “less than” refers primarily to “5 percent” which only in turn is an expression of the number of women. But 5 percent could be 26.7 percent (eight of thirty women); the percentage itself is an amount that cannot be counted because, theoretically, it is infinitely divisible.

Fowler’s points out that “less” has not always been considered incorrect with countable things (the usage began to face condemnation in the eighteenth century). It is a matter of the right idiom and not really a matter of meaning. If you were to say “there are less than five cats in this room,” no one would ever misunderstand you (unless you meant to imply that such-and-such a cat just wasn’t living up to her feline potential)—but our idiomatic ears say “ouch” and ask for “fewer.”