Be consistent in your use of numbers. When you write about numbers used in examples or UI, duplicate them exactly as they appear in the UI. Otherwise, use the following guidelines.
Numerals versus words
In general, spell out whole numbers from zero through nine, and use numerals for 10 or greater. It’s acceptable to use numerals for zero through nine when you have limited space, such as in tables—but do so consistently.
However, there are many exceptions to this rule.
If one item requires a numeral, use numerals for all the other items of that type.
Correct: One article has 16 pages, one has 7 pages, and the third has only 5 pages.
Incorrect: One article has 16 pages, one has seven pages, and the third has only five pages.
Avoid mixing spelled-out numbers and numerals when using them to compare information.
Correct: The general timeframe ranges from 10 hours for a simple cyber liability line to 600 hours for a complex commercial line.
Incorrect: The general timeframe ranges from ten hours for a simple cyber liability line to 600 hours for a complex commercial line.
Beginning a sentence
Spell out numbers when they begin a sentence. Don’t start a sentence with a numeral. You can also rewrite the sentence by adding a modifier or moving the number to a different position. Rewriting is helpful for maintaining consistency if there are multiple numbers in the sentence.
Correct: Five of the modules include this functionality.
Incorrect: 5 of the modules include this functionality.
Acceptable: Eleven apps are included.
Better: More than 10 apps are included.
Best: The software includes 11 apps.
Note: It’s okay to start list items with numerals—use your judgment.
Using two numbers together
When two numbers that refer to different things must appear together, use a numeral for one and spell out the other.
fifteen 20-page articles
When presenting a range of numbers, use an en dash instead of a hyphen between the range. To create an en dash on a Mac keyboard, press Option+Hyphen.
Refer to the following table for instances in which you should use numerals instead of words.
|Use numerals for:||Examples|
|Measurements of distance, temperature, volume, size, weight, pixels, points, and so on—even if the number is less than 10.||3 feet, 5 inches|
80 × 80 pixels
|A number the reader is directed to type.||Enter 5.|
|A round number of 1 million or more.||7 million|
|Dimensions. Spell out by, except for tile sizes, screen resolutions, and paper sizes. For those, use the multiplication sign (×). Use a space before and after the multiplication sign.||10-foot cable|
4 × 4 tile
8.5" × 11" paper
1280 × 1024
|Time of day. Include a.m. or p.m.|
Don't use numerals for 12:00. Use noon or midnight instead.
Include the time zone if you're discussing an event, and customers beyond the local time zone may see it. Time stamps in UI and websites usually display local time and date automatically.
The meeting is at noon.
The event starts at 5:00 p.m. Pacific Time.
The date changes at midnight.
|Percentages, no matter how small. Use a numeral plus percent to specify a percentage. Use percentage when you don't specify a quantity.||At least 50 percent of your system resources should be available.|
Only 1 percent of the test group was unable to complete the task.
A large percentage of system resources should be available.
|Coordinates of tables or worksheets and numbered sections of documents.||row 3, column 4|
See the Microsoft Style Guide for more information on numbers usage.