Spell out small numbers (one to nine), never start a sentence with digits, and use digits for most larger numbers and in recipes. Beyond these basics, style guides differ, so the most important rule is to pick one style and use it consistently.
One of the big questions many people have about writing is how to write numbers. Should you write "12 days" or "twelve days"? Is it "4 puppies" or "four puppies"? And are there specific rules you need to follow, or does it always depend on the situation?
Part of the confusion comes from the fact that there isn't one answer. Whether you should use digits or spell out the word depends on the situation. Here are some easy rules that make it a little clearer.
The basic rules
In this article, "digits" means numbers written as 1, 3, 14, or 27, and "spelling out" means writing them as words: one, three, fourteen, or twenty-seven.
- Spell out small numbers. Almost every style guide agrees on this one: if a whole number is smaller than 10, write it as a word.
- Never start a sentence with digits, however big the number is. Don't write "2,000 tickets were sold for the event." Write "Two thousand tickets were sold for the event." With larger numbers, it is often best to reword the sentence so that it doesn't start with a number at all: "The event sold 2,000 tickets."
- Spell out round, approximate numbers in formal writing: "about a hundred guests" rather than "about 100 guests". Style guides differ here, though: news style writes "about 100,000", while book style writes "about one hundred thousand".
- Separate numbers that stand next to each other. When two numbers come together, spell out one of them for clarity, because two digits or two words in a row are confusing. Instead of "7 3-inch note cards", write "seven 3-inch note cards".
- Be consistent within a sentence. Many style guides ask you to write numbers for the same kind of thing the same way when they appear together: "She has 3 dogs and 12 cats" rather than "She has three dogs and 12 cats".
- Use digits in recipes: "Add 2 cups of flour and bake for 25 minutes."
- Spell out small ordinal numbers. When you talk about your first love, write "first love", not "1st love". Larger ordinals follow the same rule as other numbers in your style: "the 21st century" in news style, "the twenty-first century" in book style.
When the basic rules don't decide it
Beyond these rules, it gets a little tricky, because the style guides disagree:
| Style | Spell out | Use digits |
|---|---|---|
| AP style (news) | one to nine | 10 and up |
| Chicago style (books) | zero to one hundred, and round numbers | 101 and up |
| One-word rule | numbers that are one word: eleven, twenty | numbers that need a hyphen: 28 |
So with the one-word rule, you would write twenty, eleven, and 28. Numbers like twenty-seven are hyphenated when you spell them out; the guide to the hyphen explains why.
If your school, publisher, or company has a style guide, follow it. If not, choose one of these approaches and stick to it throughout the text. Consistency in business writing shows how to keep this and other choices the same from page to page, and writing dates and times covers the numbers in a date.
It can be a challenge to remember all the rules for writing numbers, but once you have a style, you make a much more polished impression on whoever reads your writing.