Numbers in Writing: When to Spell Out and When to Use Digits

Basic Number-Writing Guidelines

Writers often pause over a simple choice: should the sentence use 7 or seven? There is no single rule that fits every publication. Your answer depends partly on the style guide you are using and partly on the kind of number involved. Still, most English style systems follow the same broad idea: write smaller numbers as words and write larger numbers as numerals.

The cutoff point is where guides differ. These are the two rules you will see most often:

• Spell out one through ninety-nine; use digits for 100 and above (Chicago Manual of Style)
• Spell out one through nine; use digits for 10 and above (AP Stylebook, APA Style)

Either approach is acceptable in many settings. What matters most is that you pick a system and use it steadily across the same document. Visit dictionary.wiki for more help with English writing conventions.

How Major Style Guides Handle Numbers

AP and APA are easy to apply because they draw the line after nine. That makes them popular in journalism, workplace writing, and general nonfiction. Chicago’s broader spelling-out rule, which covers one through ninety-nine, is more common in books and literary writing.

Places Where Words Are the Better Choice

No matter which style guide you follow, some number uses normally call for words instead of numerals:

At the Start of a Sentence

A sentence should not begin with a numeral. Spell the number out, or recast the sentence so the numeral appears later:

Incorrect: 275 guests filled the auditorium.

Correct: Two hundred seventy-five guests filled the auditorium.

Also correct: The auditorium held 275 guests.

Approximate or Indefinite Amounts

• Several dozen applications arrived before noon.
• The video received thousands of views overnight.
• The office handled hundreds of calls that week.

Side-by-Side Numbers

If two numbers fall next to each other, spell out one of them so the reader can parse the phrase quickly:

Confusing: The clerk packed 18 6-ounce jars.

Clear: The clerk packed eighteen 6-ounce jars.

Fixed Phrases and Well-Known Expressions

• zero tolerance
• the Twelve Apostles
• the Four Horsemen of the Apocalypse

Places Where Numerals Are Expected

In several common contexts, digits are standard even when the number is small:

Street Addresses

• 841 Oak Avenue, Unit 2C

Pages, Chapters, and Numbered Sections

• Turn to page 9 for the chart. Chapter 4 explains the method.

Scientific and Technical Contexts

Scientific writing usually favors numerals because they make exact values easier to scan and compare.

Game Scores and Vote Counts

• The match ended 4–2. The proposal failed 6 to 5.

Precise Statistical Counts

• The study analyzed 2,846 responses.

Writing Dates and Clock Times

Calendar Dates

Dates are usually written with digits:

• American format: January 15, 2025
• British format: 15 January 2025
• Numerical: 1/15/2025 (US) or 15/01/2025 (UK/international)

The difference between British and American date formats can cause real confusion, especially when people in different countries read the same numerical date.

Clock Times

• The train leaves at 6:45 a.m.
• Lunch is scheduled for noon (or 12:00 p.m.).
• The lecture starts at 8 o'clock.

Decades and Centuries

• the twenty-first century (often spelled out in ordinary prose)
• the 1990s (not 1990's — no apostrophe)
• the '90s (the apostrophe marks the missing digits)

Writing Amounts of Money

• Large sums often combine numerals and words: $4.5 million, $12 billion
• Exact prices and amounts take digits: $5.99, £10, €200
• Do not double the currency label: write $100 or 100 dollars, not "$100 dollars"
• Approximate or rounded sums may be written out: "roughly fifty dollars"

Percentages, Data, and Statistics

With percentages, most style guides prefer numerals:

• Enrollment increased by 18 percent. (AP style: spell out "percent")
• Enrollment increased by 18%. (APA/scientific style: use the symbol)

When a percentage begins a sentence, write out both the number and the word "percent":

Eighteen percent of students chose the online option.

Units, Sizes, and Measurements

Measurements are generally written with digits:

• The ladder is 8 feet tall.
• Mix in 3 tablespoons of oil.
• The afternoon temperature reached 95°F.
• The tower stands 200 meters high.

In technical and scientific material, units are often abbreviated: 6 ft, 200 m, 2 tbsp.

Big Numbers and Rough Amounts

For very large values, a mix of digits and words is usually easier to read than a long string of digits:

• 7.8 billion people on Earth
• $3.2 million (rather than $3,200,000 in general writing)
• 1.5 trillion dollar deficit

Using Commas in Long Numbers

In numbers with four or more digits, use commas to mark groups of three digits:

• 25,000 (twenty-five thousand)
• 1,000 (one thousand)
• 1,234,567

Some numbers do not take commas: years (2025, not 2,025), page numbers, addresses, and serial numbers.

Number Hyphenation

Numbers connect with hyphenation rules in a few predictable patterns:

Spelled-Out Compound Numbers

Use hyphens in written-out numbers from twenty-one through ninety-nine:

• twenty-one, thirty-five, fifty-eight, ninety-nine

Number Phrases Before Nouns

When a number plus a unit modifies a noun that follows it, hyphenate the compound modifier:

• a 15-minute interview
• a 300-page manual
• a five-star review
• a three-year contract

Fraction Modifiers

Fractions are hyphenated when they work as modifiers:

• a two-thirds majority
• a one-half share

Keeping Number Style Consistent

Consistency is one of the strongest rules for numbers. If one sentence or paragraph compares numbers in the same category, and some are above your usual cutoff while others are below it, use digits for all of them so the series looks unified:

Inconsistent: The clinic has two nurses, six assistants, and 14 physicians.

Consistent: The clinic has 2 nurses, 6 assistants, and 14 physicians.

If the numbers describe different kinds of things, mixing words and digits can be fine:

The 12 participants completed three rounds of testing.

In that example, 12 counts people, while three counts rounds, so the mixed style does not distract.

Frequent Number-Writing Mistakes

Mistake 1: Opening a Sentence with a Numeral

Incorrect: 23 homes lost power.

Correct: Twenty-three homes lost power.

Mistake 2: Mixed Formatting in One Series

When the numbers belong to the same category and are being compared, format them the same way.

Mistake 3: Adding an Apostrophe to a Decade

Incorrect: the 1980's

Correct: the 1980s

Mistake 4: Repeating the Currency Label

Incorrect: $50 dollars

Correct: $50 or 50 dollars

Main Points to Remember

• Use your chosen style guide: AP/APA spell out 1–9; Chicago spells out 1–99.
• Do not begin a sentence with a numeral.
• Use numerals for dates, times, addresses, page numbers, percentages, and measurements.
• For large numbers, combine digits with words: $3.2 million, 7.8 billion.
• Use hyphens in compound numbers (twenty-one) and number-unit modifiers (10-minute break).
• Keep number style consistent when the numbers in a sentence or paragraph refer to the same kind of thing.
• Do not use an apostrophe in ordinary decades: the 1990s, not 1990's.

Number style is mostly about clarity and consistency. Choose the rule your guide requires, make exceptions for standard uses such as dates and measurements, and keep comparable numbers looking alike. For related help, see our guides to hyphenation rules, capitalization rules, and abbreviations and acronyms.