When to Spell Out Numbers According to Different Style Guides

Each editorial style manual—including AP, APA, MLA, Chicago Manual of Style—has different rules for spelling out numbers in text. In some cases, words are used to describe an amount, whereas, in others, you use numerals. In almost all cases, numbers that begin a sentence are spelled out. However, it is important to keep in mind each writing style has exceptions to some of its rules, especially when dealing with larger numbers, fractions, and whole numbers.

The American Psychological Association (or APA) style manual typically focuses on scientific writing but can be used in online editorial. spelling out numbers follows the general rules below:

1. 1. Spell out numbers below 10. Numerals should be used for numbers 10 and above, but numbers nine and below should be spelled out.
2. 2. Spell out numbers at the beginning of a sentence. A number that begins a sentence should be spelled out rather than noted as a numeral, even if the number is below 10.
3. 3. Spell out common fractions or phrases with numbers. Spell out numbers when they are part of common phrases or fractions. For example, you spell out the number in “The Twelve Days of Christmas” rather than using the numeral. If you’re using a common fraction or percentage like “one in fifteen people,” you also should spell out your numbers.
4. 4. Use numerals for measurements. If a number precedes a measurement (5 cm, 7g), use the numeral form rather than spelling it out.
5. 5. Use numerals for fractions, ratios, and percentages. Any number used for data and statistics (75%, 6:1) should use the numeral form rather than the word spelling.
6. 6. Use numerals for sums of money, dates, ages, and time. If you’re discussing numbers like dollar amounts (3 dollars) or somebody’s age (7 years old), use numerals rather than spelling.
7. 7. Numbers in a series. When you’re referring to a number in a series—like Grade 7, or District 4—you use the numeral and capitalize the noun that precedes it.

The Chicago Style Manual details its own guidelines for including numbers within a text.

1. 1. Spell out numbers zero through one hundred. Use numeral figures to represent numbers above one hundred, but spell out whole numbers like three hundred or one thousand. Use numerals to represent non-whole numbers, such as 1,239 or 603.
2. 2. Spell out cents for amounts less than one dollar. For amounts less than a dollar, avoid using a dollar sign or decimal point, and instead spell out the type of change. For example, “Soda only used to cost 25 cents.”
3. 3. Spell out numbers at the beginning of a sentence. If a number begins a sentence, it should be spelled out rather than noted as a numeral.
4. 4. Spell out large rounded numbers. Large whole numbers over 100 that are followed by hundred, thousand, hundred thousand, or million, should be spelled out unless they refer to amounts of money.
5. 5. Use numerals for fractions. Use numerals to represent your common fractions (8 ½, 4 ¾) unless they begin a sentence, in which case you would use words to spell them out (Eight and one-half, four and three-fourths).

Below are a few formatting tips for following the Modern Language Association (or MLA) Style Guide for numbers.

1. 1. Spell out numbers at the beginning of a sentence. If a number begins a sentence it should be spelled out rather than noted as a numeral.
2. 2. Spell out simple numbers. If a number can be written with one or two words (fourteen, ninety-nine), it is spelled out. Numerals should be used in all other instances.
3. 3. Hyphenate compound numbers. Hyphens should be used for numbers from twenty-one to ninety-nine.
4. 4. Use symbols and abbreviations. Writers should pair numerals with their appropriate symbols, such as “$” or “%” when necessary.

The Associated Press style also comes with its own set of rules for styling numbers, listed below.

1. 1. Spell out numbers one through nine. Use numerals for numbers 10 and greater. Ordinal numbers (i.e., third, 12th), follow the same basic rule.
2. 2. Spell out numbers at the beginning of a sentence. If a number begins a sentence it should be spelled out rather than noted as a numeral.
3. 3. Use numerals for money. With the exception of cents or amounts over one-million, all monetary amounts should express number figures rather than spelling.
4. 4. Avoid starting sentences with numerals. If a sentence starts with a number (“Seven people arrived at the station”), it should be spelled out, unless that number is a year, in which case it can appear at the beginning of the sentence in numeral form: “1865 brought about a year of tremendous change.”
5. 5. Time of day is expressed as a single number. Rather than typing out “10:00 p.m.,” time of day should be expressed as an abbreviated numeral (“10 p.m.”).

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