The Short Answer
Spell out small, simple numbers in ordinary prose, but use digits for precise data, measurements, dates, times, money, percentages, and large or complicated values. The exact cutoff depends on your style guide. Whatever convention you choose, apply it consistently and prioritize clarity for your readers.
Why Number Style Is Not Universal
Writers often expect one definitive rule for presenting numbers. In reality, conventions vary among publications, industries, and style guides.
Associated Press style generally spells out zero through nine and uses digits for 10 and above. Chicago style’s general convention spells out zero through one hundred, although it offers an alternative rule that switches to digits at 10. These differences are summarized in this useful guide to writing numbers.
That means both of these sentences may be correct:
- The company hired twelve employees.
- The company hired 12 employees.
The right choice depends on the applicable style. News articles commonly follow AP, while books and general publishing often follow Chicago. Academic, scientific, legal, and corporate writing may follow different standards or an organization’s house style.
When to Spell Out Numbers
In general writing, words are often easier to integrate into a sentence when the number is small and nontechnical:
- She bought three notebooks.
- We considered seven proposals.
- The dog waited for twenty minutes.
- He made the same mistake twice.
Spelling out numbers also works well for approximate or conversational quantities:
- Hundreds of people attended.
- I have told you a thousand times.
- The repair could cost several hundred dollars.
- Nearly a million viewers watched.
Words prevent casual estimates from appearing more precise than they really are. “About a thousand responses,” for example, feels appropriately approximate, while “about 1,000 responses” can suggest that the figure was calculated.
Number words are also usually preferable in dialogue, especially when they show how a character speaks: “I have three reasons,” she said. However, digits may still be appropriate when the character is reading a display, address, room number, or other visible figure.
When to Use Digits
Digits are usually clearer when information is exact, technical, or meant to be scanned quickly. Common examples include:
- Dates: July 18, 2026
- Times: 8:30 a.m.
- Money: $24.95
- Percentages: 6 percent or 6%
- Decimals: 3.75
- Measurements: 14 inches
- Statistics: 28 of 40 participants
- Addresses: 125 Oak Street
- Page numbers: page 7
- Scores: 4–2
- Temperature: 72°F
Digits are especially useful in tables, recipes, instructions, financial reports, and scientific material. A recipe that says “Add 2 cups of flour and 1 teaspoon of salt” is easier to scan than one that spells out every quantity.
Digits should also be used for complicated numbers that would become cumbersome as words. “The survey received 12,784 responses” is far more readable than “twelve thousand seven hundred eighty-four responses.”
Chicago recognizes that certain categories normally appear as numerals even when the values are small. Page numbers, scores, room numbers, and numbered scales are familiar examples, as explained in the Chicago Manual of Style’s guidance on numbers.
Numbers at the Beginning of a Sentence
A number at the beginning of a sentence should generally be spelled out:
- Incorrect: 17 applicants completed the interview.
- Correct: Seventeen applicants completed the interview.
Large numbers can make this rule awkward:
- Seven thousand eight hundred forty-two customers completed the survey.
The cleaner solution is usually to revise the sentence:
- The survey was completed by 7,842 customers.
Rewriting is particularly helpful with decimals, percentages, and monetary amounts. Instead of beginning with “47.5 percent,” write, “A total of 47.5 percent of respondents agreed.”
Years are sometimes treated as an exception, particularly in journalistic writing: “2020 changed the way many offices operated.” Nevertheless, rewriting may produce a smoother sentence: “The year 2020 changed the way many offices operated.”
How to Handle Fractions and Compound Numbers
Simple fractions are often written as words in ordinary prose:
- Two-thirds of the audience remained.
- She ate one-half of the sandwich.
- The project is three-quarters complete.
Written-out fractions are generally hyphenated, although common expressions such as “a half” and “a third” do not need hyphens. Numerical fractions are better for recipes, formulas, measurements, and technical instructions: “Cut the board to 5½ feet.”
Compound numbers from twenty-one through ninety-nine should also be hyphenated when spelled out:
- twenty-four
- fifty-seven
- ninety-nine
Whole numbers containing “hundred” or “thousand” do not require extra hyphens: “three hundred,” “six thousand,” and “twenty-four thousand.”
Consistency Within a Sentence
Even when individual choices follow a style guide, mixing words and digits carelessly can distract readers.
Consider this sentence:
- The shelter housed eight dogs, 14 cats, and six rabbits.
Under AP style, that treatment follows the standard cutoff, but the visual difference may feel uneven because all three numbers belong to the same category. Depending on the context, an editor might prefer digits throughout:
- The shelter housed 8 dogs, 14 cats, and 6 rabbits.
Clarity should guide the decision, particularly when a passage contains many statistics. The broader relationship between conventions and readability is explored in the intersection of grammar and writing style.
Be especially careful when two numbers appear next to each other. Writing one as a word can prevent confusion:
- The warehouse received twelve 50-pound bags.
- We ordered three 10-inch frames.
This approach clearly separates the quantity of items from the measurement or description attached to each item.
Common Mistakes to Avoid
Watch for these frequent number-formatting problems:
- Switching conventions without a reason: Do not write “seven employees” in one paragraph and “7 employees” in the next.
- Adding unnecessary words: Write “$500,” not “$500 dollars.”
- Using apostrophes in decades: Write “the 1990s,” not “the 1990’s.”
- Attaching ordinal endings to full dates: Write “August 25,” not “August 25th,” in standard American date formatting.
- Spelling out long exact values: Digits are clearer for figures such as 16,492.
- Overusing double forms: Avoid constructions such as “five (5) copies” unless a legal or specialized format requires them.
- Ignoring the audience: A novel, laboratory report, news story, and sales dashboard do not need identical number styles.
Rules are tools rather than ends in themselves. As the discussion of why grammar conventions can be flexible explains, context and communication should influence stylistic choices.
A Practical Editing Checklist
When reviewing numbers in your writing, ask:
- Am I following a required style guide?
- Have I used the same cutoff consistently?
- Did I spell out a number that begins a sentence?
- Would digits make this information easier to scan?
- Is the number an exact measurement, date, time, price, or statistic?
- Are similar numbers presented in a visually consistent way?
- Could I rewrite the sentence to remove an awkward construction?
- Does my choice make the meaning immediately clear?
Ultimately, effective number style balances convention with readability. Spell out numbers when words fit naturally into prose, and use digits when precision or quick recognition matters. If no formal style guide applies, choose a sensible rule, record it in a brief style sheet, and follow it throughout the document.