When and How to Write Numbers as Words

Whether you’re drafting a legal contract, writing a check, or polishing an academic paper, knowing when to spell out numbers and when to use digits is an essential writing skill. The rules vary depending on which style guide you follow, and getting them wrong can look unprofessional or even cause financial disputes.

This guide walks through the major conventions for writing numbers as words, explains when each style applies, and offers practical advice for the situations where writers most commonly make mistakes.

The Two Major Style Guide Rules

AP Style (Journalism and Marketing)

The Associated Press Stylebook is the standard for news writing, blog posts, press releases, and most marketing copy. Its core rule is simple:

• Spell out numbers one through nine.
• Use digits for 10 and above.

Examples:

• “She adopted three cats.” (under 10 = spelled out)
• “The company hired 47 new employees.” (10+ = digits)

Exceptions in AP Style:

• Ages always use digits: “The 3-year-old child.”
• Addresses always use digits: “9 Elm St.”
• Percentages always use digits: “7% increase.”
• Money uses digits for specific amounts: “$5 million.”

Chicago Manual of Style (Books and Academic Work)

The Chicago Manual of Style is used in book publishing, academic papers, and long-form writing. Its rule is more generous with spelled-out numbers:

• Spell out numbers zero through one hundred.
• Use digits for 101 and above.

Examples:

• “The recipe calls for twelve eggs.”
• “The building has forty-seven floors.”
• “The dataset contains 1,042 entries.”

Chicago also recommends spelling out round numbers that can be expressed in one or two words: “two hundred,” “thirty thousand,” “six million.”

Universal Rules That Apply Everywhere

Regardless of which style guide you follow, a few rules are nearly universal across all formal English writing.

Never Start a Sentence with a Digit

If a number falls at the beginning of a sentence, spell it out or restructure the sentence.

• Wrong: “350 people attended the conference.”
• Right: “Three hundred fifty people attended the conference.”
• Also right: “The conference drew 350 attendees.”

If the number is very large and spelling it out would be awkward, rewrite the sentence so the number appears later.

Be Consistent Within a Passage

When comparing numbers in the same sentence or paragraph, use the same format for all of them, even if some would normally be spelled out.

• Inconsistent: “We ordered three desks, 15 chairs, and seven monitors.”
• Consistent: “We ordered 3 desks, 15 chairs, and 7 monitors.”

Hyphenate Compound Numbers

Spelled-out numbers between twenty-one and ninety-nine always take a hyphen: twenty-one, thirty-five, sixty-eight, ninety-nine.

Writing Numbers on Checks and Legal Documents

On personal checks, you write the amount in both digits and words. The written-out version is the legally binding amount if the two disagree. This makes accuracy critical.

Format: “One thousand two hundred fifty and 47/100”

Key rules for check writing:

• Start at the far left of the line to prevent tampering.
• Use “and” only to separate dollars from cents.
• Write cents as a fraction over 100.
• Draw a line through remaining blank space on the line.

For legal contracts and loan documents, amounts are typically written with the numeral in parentheses after the words: “Five Thousand Dollars ($5,000).” This provides a double-check and reduces ambiguity.

Numbers in Formal and Technical Writing

Scientific and Technical Papers

Scientific writing almost always uses digits, even for small numbers, when they accompany units of measurement:

• “The sample weighed 3 grams.”
• “Heat to 5 degrees Celsius.”

However, spell out numbers that don’t accompany measurements: “The experiment was repeated four times.”

Financial Reports

Financial documents typically use digits for all dollar amounts and percentages but may spell out round numbers in narrative sections: “Revenue grew by approximately two million dollars.”

Recipes and Instructions

Recipes typically spell out small quantities (“two cups,” “one teaspoon”) but use digits for temperatures and times (“350 degrees,” “15 minutes”).

Common Mistakes to Avoid

Mixing Formats Without Reason

Switching between digits and words randomly within a document confuses readers and looks careless. Pick a style and stick with it.

Forgetting Hyphens in Fractions

Spelled-out fractions need hyphens when used as adjectives: “a two-thirds majority.” When used as nouns, some style guides drop the hyphen: “Two thirds of the class passed.”

Omitting Commas in Large Numbers

Numbers with four or more digits need commas (or spaces, in some locales): 1,000 not 1000, 25,000 not 25000. Some technical and scientific contexts use spaces instead of commas: 25 000.

Writing “and” in Whole Numbers

In American English, “and” is reserved for the decimal point. You write “one hundred twenty-three,” not “one hundred and twenty-three.” British English permits the “and.”

Quick Reference Table

Situation	Format	Example
Start of sentence	Words	”Twelve students passed.”
AP Style, 1-9	Words	”She has four siblings.”
AP Style, 10+	Digits	”He ran 26 miles.”
Chicago, 0-100	Words	”The town has ninety-two houses.”
Chicago, 101+	Digits	”The town has 102 houses.”
Checks	Words + digits	”Two hundred and 50/100”
Legal documents	Both	”Ten Thousand Dollars ($10,000)“
Measurements	Digits	”5 grams”
Percentages	Digits	”8% growth”

Using a Number-to-Words Tool

When you need to write large numbers in word form, such as for checks, invoices, or legal contracts, manually converting something like 1,247,893 into words is tedious and error-prone. Our Number to Words Converter handles this instantly, giving you the correctly formatted word version ready to paste into your document.

Frequently Asked Questions

When should I use “and” in a spelled-out number?

In American English, “and” is used only to indicate a decimal point or to separate dollars from cents on checks. You would write “three hundred fifty,” not “three hundred and fifty.” British English conventions differ and commonly include “and” in whole numbers, as in “three hundred and fifty.”

Do I spell out ordinal numbers like “first” and “second”?

Follow the same rules as regular numbers. In AP Style, spell out first through ninth and use digits with suffixes for 10th and above. In Chicago Style, spell out first through one hundredth. Always spell out ordinals at the start of a sentence.

How do I write very large numbers like millions or billions?

Combine digits with words for readability: “2.5 million,” “300 billion.” This is standard in both AP and Chicago styles. Avoid writing out every digit unless required by a legal document, where you might write “Two Million Five Hundred Thousand Dollars ($2,500,000).”

Should I spell out numbers in tables and charts?

No. Tables, charts, graphs, and data-heavy contexts should always use digits for clarity and space efficiency. Spelled-out numbers in tabular data make columns harder to scan and compare.

What about numbers with decimals?

Always use digits for numbers with decimals: “3.14,” “0.75,” “98.6 degrees.” Spelling out decimal numbers (“three point one four”) is reserved for spoken language or very informal writing.