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. In all other content, follow the guidelines below.
Numerals or words
In body text, spell out whole numbers from zero through nine, and use numerals for 10 or greater. It's OK to use numerals for zero through nine when you have limited space, such as in tables and UI. For example:
- 10 screen savers
- five databases
- zero probability
- 7,990,000
- 1,000
Spell out zero through nine and use numerals for 10 or greater for days, weeks, and other units of time. For example:
- seven years
- 28 days
- 12 hrs
If one item requires a numeral, use numerals for all the other items of that type for consistency. For example:
- One article has 16 pages, one has 7 pages, and the third has only 5 pages.
When two numbers that refer to different things must appear together, use a numeral for one and spell out the other. For example:
- fifteen 20-page articles
Avoid starting a sentence with a numeral. If you can’t rewrite the sentence, spell out the number. It's OK to start list items with numerals — use your judgment. For example:
- More than 10 apps are included.
- Eleven apps are included.
Always use numerals in the following situations:
| 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 1.76 lb 80 × 80 pixels 0.75 grams 3 centimeters 3 cm |
| A number the customer is directed to enter. | 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.
|
10∶45 AM 6∶30 PM The meeting is at noon. The event starts at 5 PM Pacific Time. The date changes at midnight. |
Percentages, no matter how small.
|
At least 50% of your system resources should be available. Only 1% 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 Volume 2 Chapter 10 Part 5 step 1 |
Ordinal numbers
Always spell out ordinal numbers.
- the first row
- the twenty-first anniversary
Don't use ordinal numbers, such as June first, for dates.
Don't add -ly to an ordinal number, as in firstly or secondly.
Compound numbers
Hyphenate compound numbers when they're spelled out. For example:
- twenty-five fonts
- the twenty-first day
Ranges of numbers
In most cases, use from and through to describe a range of numbers. Use an en dash in a range of pages or where space is an issue. Omit from if the range is clear without it. For example:
- from 9 through 17
- ages 8 through 10
- pages 112–120
- 10:30 AM–2:30 PM
- May 1–June 7
- May through October
In ranges of times, use to instead of through.
- 10∶30 AM to 2∶30 PM
Dates
Use the following US conventions to indicate specific dates: June 1, 2023
- Spell out the month or abbreviate it with the first three letters and a period (May is not abbreviated).
- Follow the month with the day number; do not use a leading zero or ordinal numbers (first, second…).
- Follow the day with a comma and the year if needed.
Phone numbers
Use hyphens — not parentheses, periods, spaces, or anything else — to separate the parts of a phone number. For example:
- Example: 612-555-0175
For information about how to format phone numbers in a region outside the United States and Canada, refer to the localization style guide for that region.
Units
In measurements where the unit of measure is spelled out, use the plural form for all cases except when the quantity is exactly 1. For example:
- 0.5 inches
- 0 inches
- 1 inch
- 5 inches
Abbreviations
Don't abbreviate thousand, million, and billion as K, M, and B. Spell out thousand, million, and billion, or use the entire number.
- Fabrikam, Inc., employs more than 65,000 people.
- Total cost to the enterprise: 300,000 hours and $30 million per year
Negative numbers
Form a negative number with a minus sign, not a hyphen. For example:
- −79
Commas in numbers
Use the following US conventions:
Use commas in numbers that have four or more digits. When indicating years or pixels, use commas only when the number has five or more digits. For example:
- $1,024
- 1,093 MB
- 2500 B.C.
- 10,000 B.C.
- 1920 × 1080 pixels
- 10,240 × 4320 pixels
Don't use commas in page numbers, addresses, or after the decimal point. For example:
- page 1091
- 15601 NE 40th Street
- 1.06377 units
Decimals
In tables, align decimals on the decimal point if possible.
Add a zero before the decimal point for decimal values between −1 and 1. For example:
- 0.5 cm
- enter 0.75"
Fractions and math
Express fractions in words, as symbols, or as decimals, whichever is most appropriate.
Don't express fractions as numerals separated by a slash.
- Don’t: 1/3 + 1/6 = 1/2
- Do: ⅓ + ⅙ = ½
Exception: When an equation occurs in text, it's OK to use a slash between the numerator and the denominator. Or, in Microsoft Word, go to the Insert tab, and select Equation to format the equation automatically.
- ½ + ½ = 1
Hyphenate spelled-out fractions. Connect the numerator and denominator with a hyphen unless either already contains a hyphen. For example:
- one-third of the page
- two-thirds completed
- three sixty-fourths
Simple math notation that can easily be represented with plain text: use plain text.
Complex math notation (fractions, differentials, etc.):
- For HTML output, use MathML and ensure that your delivery uses a technology such as MathJax that can render the math correctly both visually and textually for accessibility.
- In Microsoft applications, use MathType.
Do not use images to represent math notation unless you have no alternative. If you must use an image, ensure that the alternative text correctly describes the math.