The Quick Answer
Write out numbers zero through nine in most prose. Use digits for 10 and above. On checks and legal documents, always write the amount in words alongside the numeric figure.
For fast conversions, use our number to words converter to instantly spell out any number.
When to Spell Out Numbers
The answer depends on context. Here are the most common scenarios and their rules.
Checks and Banking
When writing a check, the amount in words is the legally binding figure — not the numeric amount in the box. Banks use the written-out version to resolve disputes.
Format: Write the dollar amount in words, then add "and" before the cents expressed as a fraction of 100.
| Numeric | Written on Check |
|---|---|
| $45.00 | Forty-five and 00/100 |
| $1,250.75 | One thousand two hundred fifty and 75/100 |
| $300.00 | Three hundred and 00/100 |
| $0.99 | Zero and 99/100 |
Tips for check writing:
- Start writing at the far left of the line to prevent tampering
- Draw a line through any remaining space after the amount
- Write "and" only once — between dollars and cents
- Do not use "dollars" in the word line (it's usually preprinted)
Legal Documents
Contracts, deeds, and wills typically include both forms: the number in words followed by the numeric figure in parentheses.
Example: "The purchase price shall be Three Hundred Fifty Thousand Dollars ($350,000)."
The words take precedence if the two forms conflict. This is why accuracy matters — and why it helps to convert the number automatically to avoid mistakes.
Academic and Formal Writing
Style guides differ, but here are the three major ones:
| Style Guide | Rule |
|---|---|
| AP Style | Spell out one through nine. Use digits for 10 and above. |
| Chicago Manual of Style | Spell out zero through one hundred and round numbers (two hundred, three thousand). |
| APA Style | Spell out numbers below 10. Use digits for 10 and above. |
All three agree on these exceptions:
- Spell out a number that starts a sentence: "Forty-seven people attended."
- Use digits for measurements, statistics, and technical data: "5 mg," "3.7%"
- Use digits for dates, addresses, and page numbers
- Be consistent within a paragraph — if one number needs digits, use digits for all related numbers
Everyday Writing
In emails, blog posts, and informal text, consistency matters more than rigid rules. A practical approach:
- Spell out small numbers (one through nine)
- Use digits for larger numbers (10+)
- Always use digits when precision matters (measurements, money, data)
- Spell out round numbers in casual contexts ("about two hundred people")
How to Spell Numbers: The Complete Rules
Ones Through Nineteen
These are unique words with no predictable pattern — they must be memorized.
| Number | Word | Number | Word |
|---|---|---|---|
| 1 | one | 11 | eleven |
| 2 | two | 12 | twelve |
| 3 | three | 13 | thirteen |
| 4 | four | 14 | fourteen |
| 5 | five | 15 | fifteen |
| 6 | six | 16 | sixteen |
| 7 | seven | 17 | seventeen |
| 8 | eight | 18 | eighteen |
| 9 | nine | 19 | nineteen |
| 10 | ten |
Tens (20–90)
| Number | Word |
|---|---|
| 20 | twenty |
| 30 | thirty |
| 40 | forty (not "fourty") |
| 50 | fifty |
| 60 | sixty |
| 70 | seventy |
| 80 | eighty |
| 90 | ninety |
Common mistake: "Forty" has no "u." This is one of the most frequent spelling errors in English.
Two-Digit Numbers (21–99)
Combine the tens word with the ones word using a hyphen:
- 21 → twenty-one
- 35 → thirty-five
- 42 → forty-two
- 99 → ninety-nine
The hyphen is not optional. "Twenty one" (without hyphen) is incorrect in standard English.
Hundreds
Use the ones word + "hundred," then add the remainder:
- 100 → one hundred
- 205 → two hundred five
- 317 → three hundred seventeen
- 999 → nine hundred ninety-nine
Note: In American English, the "and" is typically omitted ("three hundred seventeen"). In British English, "and" is standard ("three hundred and seventeen"). Both are acceptable.
Thousands, Millions, and Beyond
| Scale | Number | Word |
|---|---|---|
| Thousand | 1,000 | one thousand |
| Million | 1,000,000 | one million |
| Billion | 1,000,000,000 | one billion |
| Trillion | 1,000,000,000,000 | one trillion |
Combining scales:
- 2,500 → two thousand five hundred
- 15,000 → fifteen thousand
- 100,000 → one hundred thousand
- 1,234,567 → one million two hundred thirty-four thousand five hundred sixty-seven
For very large numbers, our number to words converter handles the conversion up to 999 trillion.
Decimals
Write "point" followed by each digit individually:
- 3.5 → three point five
- 0.25 → zero point two five
- 99.99 → ninety-nine point nine nine
In financial contexts, decimals are usually expressed differently (see the check-writing section above).
Negative Numbers
Prefix with "negative" or "minus":
- −5 → negative five
- −100 → negative one hundred
Fractions
- ½ → one-half
- ⅓ → one-third
- ¼ → one-quarter (or one-fourth)
- ⅔ → two-thirds
- ¾ → three-quarters (or three-fourths)
For mixed numbers: 2½ → two and one-half.
Common Mistakes
"Forty" vs. "Fourty"
The correct spelling is forty — no "u." This applies to forty, fourteen, and fourth (but "four" keeps the "u").
Hyphens in Compound Numbers
Always hyphenate compound numbers from twenty-one through ninety-nine, whether they stand alone or are part of a larger number:
- ✅ forty-two
- ✅ three hundred forty-two
- ❌ forty two
- ❌ three hundred and forty two
"And" in Number Words
In American English, "and" is reserved for the decimal point or the cents portion on checks:
- ✅ one hundred fifty (American)
- ✅ one hundred and fifty (British)
- ✅ two hundred and 50/100 (checks — "and" separates dollars from cents)
Capitalizing Number Words
On checks: capitalize the first word. In legal documents: often title case. In prose: follow normal sentence rules.
When to Use Digits Instead of Words
Even style guides that favor spelling out numbers make exceptions. Always use digits for:
- Dates: February 4, 2026 (not "February four")
- Times: 3:30 PM (not "three thirty PM" in most contexts)
- Addresses: 42 Oak Street (not "forty-two Oak Street")
- Page numbers: page 7
- Percentages: 5% or 5 percent (style varies, but digits for the number)
- Measurements: 3 km, 150 lbs, 98.6°F
- Money with cents: $4.99 (not "four dollars and ninety-nine cents" in most prose)
- Technical and statistical data: "The sample size was 250"
- Phone numbers, codes, and identifiers: 555-0100, Room 204
Frequently Asked Questions
How do you write a check amount in words?
Write the dollar amount in words, add "and," then express the cents as a fraction over 100. For example, $1,530.45 is "One thousand five hundred thirty and 45/100." Start writing at the far left of the line and draw a line through any unused space.
Is it "forty" or "fourty"?
The correct spelling is forty. There is no "u" in forty. This is a common English spelling irregularity — "four" has a "u" but "forty" does not.
Do you hyphenate numbers like twenty one?
Yes. All compound numbers from twenty-one through ninety-nine require a hyphen: twenty-one, thirty-five, ninety-nine. The hyphen is standard in all major style guides.
When should I spell out numbers in an essay?
Most academic style guides (APA, AP, Chicago) agree: spell out small numbers (below 10 or below 100, depending on the guide) and use digits for larger numbers. Always spell out a number that begins a sentence. Use digits for measurements, statistics, and technical data regardless of size.
How do you write 1000 in words?
One thousand. Note there is no "and" in "one thousand" in American English. For 1,001, write "one thousand one." For 1,100, write "one thousand one hundred."
How do you write decimals in words?
Use "point" followed by each digit spoken individually. So 3.14 is "three point one four." In financial contexts, decimals are typically expressed as fractions (e.g., 75/100 on a check).
What's the difference between American and British number words?
The main difference is the use of "and." British English includes "and" after the hundreds place: "one hundred and fifty." American English typically omits it: "one hundred fifty." Both are understood worldwide.
How do you write negative numbers in words?
Prefix the number with "negative" or "minus." For example, −25 is "negative twenty-five" or "minus twenty-five." In scientific contexts, "negative" is more common.
How do you write large numbers like millions and billions in words?
Break the number into groups of three digits (from right to left) and name each group: thousand, million, billion, trillion. For example, 2,500,000 is "two million five hundred thousand." For very large numbers, use our number to words converter to avoid errors.
Do number words need to be capitalized?
In regular prose, follow normal capitalization rules (capitalize at the start of a sentence). On checks, capitalize the first word of the amount. In legal documents, title case is common. There is no universal rule requiring number words to be capitalized.
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