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 vs. 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.
    10 screen savers
    five databases
    zero probability

  • Spell out zero through nine and use numerals for 10 or greater for days, weeks, and other units of time.
    seven years
    28 days
    12 hrs

  • If one item requires a numeral, use numerals for all the other items of that type.
    One article has 16 pages, one has 7 pages, and the third has only 5 pages.
    Microsoft Inspire is only one month and 12 days away.

  • 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

  • Don't start a sentence with a numeral. Add a modifier before the number, or spell the number out if you can't rewrite the sentence. It's OK to start list items with numerals—use your judgment.
    More than 10 apps are included.
    Eleven apps are included.

  • Use numerals in these 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. Include AM or PM.
Exception 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.
10∶45 AM
6∶30 PM
The meeting is at noon.
The event starts at 5∶00 PM 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
Volume 2
Chapter 10
Part 5
step 1

Commas in numbers

Use commas in numbers that have four or more digits.
1,093 MB

Exception When designating years, pixels, or baud, use commas only when the number has five or more digits.
2500 B.C.
10,000 B.C.
1920 × 1080 pixels
10,240 × 4320 pixels
9600 baud
14,400 baud

Don't use commas in page numbers, addresses, or after the decimal point in decimal fractions.
page 1091
15601 NE 40th Street
1.06377 units

Numbers in dates

Don't use ordinal numbers, such as June first or October twenty-eighth, for dates. Use a numeral instead: June 1, October 28.

Global tip To avoid confusion, always spell out the name of the month. The positions of the month and day vary by country. For example, 6/12/2017 might be June 12, 2017 or December 6, 2017.

Phone numbers

Use hyphens—not parentheses, periods, spaces, or anything else—to separate the parts of a phone number.

Example 612-555-0175

Global tip 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.

Negative numbers

Form a negative number with an en dash, not a hyphen:

Compound numbers

Hyphenate compound numbers when they're spelled out.
twenty-five fonts
the twenty-first day

Fractions and decimals

  • Express fractions in words, as symbols, or as decimals, whichever is most appropriate.

  • In tables, align decimals on the decimal point.

  • Add a zero before the decimal point for decimal fractions less than one, unless the customer is asked to enter the value.
    0.5 cm
    enter .75"

  • Don't use numerals separated by a slash to express fractions.

    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.
    one-third of the page
    two-thirds completed
    three sixty-fourths

  • In measurements where the unit of measure is spelled out, use the plural form when the quantity is a decimal fraction. Use the singular form only when the quantity is 1.
    0.5 inches
    0 inches
    1 inch
    5 inches

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.

Ranges of numbers

  • In most cases, use from and through to describe a range of numbers.
    from 9 through 17

    Use an en dash in a range of pages or where space is an issue, such as in tables and UI. For example, 2016–2020 and pages 112–120.
    Use to in a range of times. For example, 10∶00 AM to 2∶00 PM.

  • Don't use from before a range indicated by an en dash, such as 10–15.


In general, 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

In UI, avoid the abbreviations unless space is too limited to spell out the number.

Global tip Machine translation might not translate these abbreviations correctly. Also, an abbreviated form might not be available or might be longer in the target language, so allow space for expansion in localized content.

If you must use the abbreviations, follow these guidelines:

  • Capitalize K, M, and B.
  • Don't put a space between the number and the abbreviation.
  • Use the decimal form of a number only if it really will save space. In particular, avoid the use of a decimal with K8.21K has the same number of characters as 8,210.

See also
Date and time term collection
Units of measure term collection
Bits and bytes term collection
Dashes and hyphens
Percent, percentage
Dashes and hyphens