The AP Style Guide to Numbers

When to Round and Spell Out Numbers and Exceptions to the Rules

Mar 16, 2009

Writing numbers according to AP style can be tricky business because of all the exceptions involved, but learn these exceptions now to save yourself trouble.

When it comes to AP style, it’s easy to forget the rules because they are different from both academic and casual writing styles. Numbers can be especially tricky because AP style has so many exceptions to its own rules.

All of these exceptions and rules are serving one purpose: to make the reader’s job easier. Keep that in mind as you learn the rules for AP style, and you’ll soon be able to use your own judgment as to whether a number should be spelled out or written numerically.

The Basic Rules for Numbers in AP Style

While there are numerous exceptions, for most cases spell out numbers under 10, and use numerals for numbers 10 and above.

For large numbers of people, sums of money, etc, round unless vital to a story to include an exact number.

Thursday, 15,000 protesters danced in Garfield costumes. (Instead of Thursday, 15,218 protesters danced in Garfield costumes).

Exceptions! Always Use Numerals for...

Let the exceptions begin! Always spell out a number that begins a sentence. That is, unless it is a year. If the number is large or would be cumbersome to spell out, reword the sentence so the number doesn’t begin it. The goal is readability.

Avoid two sets of numbers back-to-back. If it is necessary to use them consecutively, spell one of the numbers out.

When to Use Roman Numerals

Use Roman numerals (IV, III) for popes, royalty and wars. Use Roman Numerals if they are a part of a brand, company or product name.

AP Style for Large Numbers

It’s time for the big ones! Those numbers most of us could only hope to earn over a lifetime. For large numbers (millions, billions, trillions, etc) do not write out the zeros but instead use numerals followed by the word: Tuesday's gathering brought together an astonishing 3.5 million participants from across the nation.

Remember, writing in AP style might seem complicated, but its ultimate goal is to simplify writing for the reader. With practice, AP style will become easier, and keep in mind that writing numbers in AP style challenges some of the greatest journalists. When in doubt, refer to the journalist’s most valuable tool: the most current copy of the AP Stylebook.