Editing 101

Apply a Consistent Style for Numbers

The basics

In general, spell out cardinal numbers and ordinal numbers below 10. Use numerals for 10 and above.

In general, spell out cardinal numbers (one, two, and so on) and ordinal numbers (first, second, and so on) below 10. Use numerals for 10 and above.

Examples
Read reviews of more than 350 restaurants in your city.
Aunt Bea’s pickles won first place at the fair.
With a premium license, install the software on three computers.
Does your building have a 13th floor?

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Percentages

Use numerals with percentages.

Use numerals with percentages.

Use either the word percent or the percent sign (%) in text—as long as you’re consistent. Consider that the percent sign saves space, and if a passage contains two or more percentages, the percent sign is easier to spot, making it easier to compare the numbers.

Examples
Workers are demanding a 5 percent raise.
In 2008, 71 percent of U.S. electricity production still came from fossil fuel.
In 2008, 71% of U.S. electricity production still came from fossil fuel. Nuclear energy accounted for 21% and hydro for 6%, with 2% coming from other sources.

Numbers in a range

In ranges of numbers, such as time periods or page ranges, the numbers can be separated by a hyphen or an en dash or by the word to.

In ranges of numbers, such as time periods or page ranges, the numbers can be separated by a hyphen or an en dash (choose one or the other and use it consistently) or by the word to. For more information about en dashes, see “Dashes.”

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Money and currency

For prices of a dollar or more, use numerals and the $ symbol.

For prices of a dollar or more, use numerals and the $ symbol: a $6 coffee.

It isn’t necessary to include the decimal and two zeros for whole dollar amounts appearing in a sentence, a headline, or an email subject line. But do include the zeros if:

  • They make sense in the context (for example, in a spreadsheet or another accounting context, in a price list, or in a shopping cart).
  • They provide consistency within a series, table, or list (for example, Chai lattes cost $2.75 for a small, $3.00 for a medium, and $3.25 for a large).

For prices under a dollar, use the word cents with the numeral: 89 cents. Don’t include the dollar sign and the leading zero (for example, $0.89) unless:

Units of measure

In general, numerals work well for expressing computer-related measurements and other units of measure on the Web—numerals save space, and they tend to catch the eye of a scanning reader. But beyond this general guideline, you have a number of choices to make.

In general, numerals work well for expressing computer-related measurements and other units of measure on the Web—numerals save space, and they tend to catch the eye of a scanning reader. But beyond this general guideline, you have a number of choices to make. For instance, you could express the dimensions of a painting as 11 by 14 inches, 11 by 14 in., or 11" x 14". In part, your choices will be based on the kind of website you have and its features and needs.

Some best practices to govern your decisions:

Fractions and decimals

Whenever possible, use decimal notation instead of fractions on the Web. Decimals are easier to hyphenate in a compound adjective, and they prevent the bad line breaks that can occur if you are using nonformatted fractions such as 1-1/2.

Whenever possible, use decimal notation instead of fractions on the Web. Decimals are easier to hyphenate in a compound adjective (for example, a 1.5-gram dose), and they prevent the bad line breaks that can occur if you are using nonformatted fractions such as 1-1/2 (for instance, where 1- appears at the end of a line and 1/2 begins the next line). See “Decimals” below for guidance on styling decimals.

Of course, sometimes fractions are appropriate: People tend to use them in recipes, for example. In contexts where fractions are commonly used and conversion to a decimal would cause confusion, stick to fractions and follow these guidelines.

Fractions

If a fraction stands alone, without a whole number (¾, for instance), spell out and hyphenate the fraction: three-quarters.

Time

Use numerals to state all times except noon and midnight.

Use numerals to state all times except noon and midnight. So, instead of 12 p.m., write noon; instead of 12 a.m., write midnight. Both 12 p.m. and 12 a.m. may cause readers to have to stop and think—noon and midnight are instantly clear to readers who scan. To avoid redundancy, don’t use the number 12 with the word noon or midnight.

Example
Before
The luncheon will start at 12 p.m.
The luncheon will start at 12 noon.
After
The luncheon will start at noon.

Dates

Each part of a date is governed by its own set of guidelines.

Each part of a date is governed by its own set of guidelines.

Days of the week

Avoid abbreviating days of the week. If abbreviations are unavoidable, use the first three letters, with a period: Mon., Tue., Wed., Thu., Fri., Sat., Sun.

Exception: In tables or in situations where space is very tight (for example, in content intended for viewing on mobile devices), periods may be omitted, and abbreviations may even be trimmed to M, Tu, W, Th, F, Sa, Su.

Months

In general, capitalize and spell out the month. The abbreviations Jan., Feb., Aug., Sept., Oct., Nov., and Dec. may be used, with periods, when:

Ages

When referring to the age of a person or an animal, use numerals.

When referring to the age of a person or an animal, use numerals.

When referring to the age of an object, spell out numbers one through nine; use numerals for 10 or more.

When making a decade reference to a person’s age (for example, She’s in her 30s), use numerals and an s without an apostrophe.

Examples
The 12-year-old boy was adopted by a couple in their 40s.
The girl was only 4 years old.
Her Siamese cat is 5 years old.
The company, which is four years old, targets 5- to 10-year-olds.
The house is 150 years old.

Phone numbers

How to format phone numbers.

Format U.S. phone numbers like this: XXX-XXX-XXXX. Include the area code but not the 1 before it that some people may have to dial.

Format phone numbers that require extensions like this: XXX-XXX-XXXX ext. XX.

Examples
415-555-XXXX
800-XXX-XXXX
707-555-XXXX ext. 29

International considerations

The primary audience for phone numbers listed on your site will most likely be people in your own country. However, the ubiquity of the Internet means that it may be wise to anticipate callers from countries other than your own. If your phone number is likely to be called by site visitors in another country, consider separate instructions; for example, “For calls originating outside the United States, dial . . . ”