Numbers in writing: when to spell them out and when to use numerals
Style guides disagree on where to switch from words to numerals, but they agree on consistency. Here are the main conventions and when to break them.
Should you write “seven” or “7”? “Twenty-five percent” or “25%”? There is no single correct answer, only conventions. What matters is choosing one and applying it the same way throughout a document.
The two main conventions
AP style: spell out one through nine
The Associated Press Stylebook, used by most American newspapers and much business writing, spells out whole numbers from one through nine and uses numerals for 10 and above.
- The team hired three engineers.
- The team hired 12 engineers.
AP also uses numerals in many categories regardless of size, including ages, percentages, dimensions, money, and dates: “a 6-year-old”, “5 feet tall”, “$4”.
Chicago style: spell out zero through one hundred
The Chicago Manual of Style, common in book publishing and some academic writing, spells out whole numbers from zero through one hundred in general prose, along with round numbers like “two thousand” or “three million”. Other numbers use numerals.
- The survey reached ninety-four households.
- The survey reached 140 households.
Chicago also recognizes the simpler zero-through-nine rule as an alternative, and technical or scientific writing often uses numerals more freely.
Neither convention is more correct. Follow the one your publication, school, or organization uses. If you have no guide, AP’s one-through-nine rule is the easier to apply consistently.
Starting a sentence
Most style guides agree: don’t start a sentence with a numeral. Spell the number out, or rewrite the sentence so it starts with something else.
Before: 47 people signed up for the workshop on the first day.
After: On the first day, 47 people signed up for the workshop.
Spelling it out works for small or round numbers (“Twelve people came”). For anything awkward, such as “Three hundred eighty-two”, rewrite instead. AP makes an exception for years: “2025 was a record year” is acceptable in AP style.
Percentages
Percentages almost always use numerals, even under rules that would spell out the number otherwise: “4 percent”, not “four percent”.
Guides differ on the symbol. Some spell out “percent” in running text; others use the % sign. AP switched to the % sign in 2019. Scientific and technical writing generally uses the sign. Pick one and use it everywhere in a document.
Consistency within a sentence
When numbers in the same category appear together, treat them the same way, even if the rule would split them.
Before: The kit includes four brushes, 12 paints, and two canvases.
After: The kit includes 4 brushes, 12 paints, and 2 canvases.
Readers compare numbers that sit side by side. Mixing words and numerals makes the comparison harder. Chicago allows this exception. Not every guide does, so check yours if you need to be strict.
Other common cases
- Very large numbers: combine numerals and words for readability: “3.2 million users”, not “3,200,000 users”.
- Two numbers in a row: spell out one of them to keep them apart: “ten 20-page reports”, not “10 20-page reports”.
- Ordinals: follow the same rule as other numbers in your style: “the third floor”, “the 21st century”.
- Approximations: words often read better for loose figures: “about a hundred people”, “a dozen times”.
- Ranges: use numerals with a hyphen or “to”: “pages 10–14”, “10 to 14 years”.
Numerals on the web and in interfaces
Writing for screens has different needs from print. Readers scan web pages and app screens instead of reading every word, and numerals stand out from text in a way spelled-out numbers do not. “3 steps” catches the eye faster than “three steps”.
For that reason, many web and interface style guides use numerals for all numbers, including one through nine. This is a deliberate choice for scannability, not a mistake.
Tip: Numerals also save space. “Delivered in 3–5 days” fits on a button or in a notification where “Delivered in three to five days” might not.
If you write for both print and the web, it is reasonable to follow a print style in documents and use numerals freely on screens. Just don’t mix the two inside one piece.
A quick checklist
- Which style guide applies? Follow it.
- Are any sentences starting with a numeral? Rewrite them.
- Are numbers of the same kind treated the same way in each sentence?
- Are percentages written the same way throughout?
- On screen, would a numeral help the reader scan?
For a wider review, see our editing checklist.