The correct spelling of the number 40 is forty. It's a single word written with an "o" after the "f" and no "u" anywhere in the middle.
If you've ever second-guessed yourself and written fourty, you're far from alone. Because the base digit is four, our brains naturally try to carry that spelling over into the tens. English spelling doesn't play by those rules here, making this one of the most frequent spelling traps in both professional writing and casual text.
Let's clear up why this exception exists, how to avoid the trap, and how to handle related number words properly.
Why Do People Spell It "Fourty"?
The root of the error is pure pattern matching. In English, we learn that the number 4 is spelled four. When we count to 14, we add -teen to get fourteen. Naturally, logic suggests that 40 should follow suit as fourty.
Language evolution doesn't always follow strict mathematical logic. Centuries ago, variants like fourty did appear in informal texts. However, as English spelling standardized during the 18th and 19th century printing booms, lexicographers locked in forty as the official standard.
Think of it like other numbers where the base form changes when a suffix or multiplier is applied:
- Five becomes fifteen and fifty (not fiveteen or fivety).
- Twenty comes from twain, losing its direct visual link to two.
- Forty drops the u entirely.
Cardinal Versus Ordinal Forms
When you're writing out numbers, you'll encounter two main forms: cardinal numbers (which show quantity) and ordinal numbers (which show position or sequence).
Cardinal Form: Forty
Use this when you're stating an exact amount of items, currency, age, or time.
- The recipe calls for forty grams of butter.
- She celebrated her forty-fifth birthday in Greece.
Ordinal Form: Fortieth
When you need to describe a rank, sequence, or anniversary, the word shifts to fortieth (spelled F-O-R-T-I-E-T-H). Note that the y changes to an i before adding -eth, just like twenty becomes twentieth.
- This gala marks the company's fortieth anniversary.
- His submission placed fortieth out of five hundred entries.
Compound Numbers and Hyphenation Rules
When you combine forty with numbers one through nine, punctuation rules kick in. According to the Chicago Manual of Style and standard English grammar guides, compound numbers from 21 through 99 require a hyphen when written out as words.
- Forty-one (not forty one)
- Forty-two
- Forty-nine
If you're using these compound numbers as adjectives directly before a noun, the hyphen remains vital for clarity. For example: "A forty-page report outlines the strategy." When the number stands alone or follows the noun, no hyphen is needed other than the standard compound form.
Style Guide Consensus
Professional editors don't debate this word. Every major style reference mandates the exact same spelling:
- Associated Press (AP) Style: Prefers numerals for numbers 13 and above in most journalistic copy, but when spelling out the tens, it must be forty.
- Merriam-Webster: Lists forty as the sole accepted standard entry, noting fourty as a common misspelling.
- Oxford English Dictionary: Confirms historical precedence dating back hundreds of years without the internal u.
Using the correct form protects your authority in emails, academic papers, and financial filings. A single misspelled number can instantly derail a reader's trust in your attention to detail.
Frequently Asked Questions
Is "fourty" ever acceptable in British or American English?
No. Neither American, British, Canadian, nor Australian English accepts fourty as a valid spelling. It is classified as a misspelling across all major English dialects.
Do words like fourteen or fourth keep the "u"?
Yes. The number four, the ordinal fourth, and the cardinal fourteen all retain the letter u. Only forty and its derivatives (fortieth) drop it.
Should I write out the word forty or use the digit 40?
It depends on your context. General publishing guidelines suggest spelling out numbers under 10 (or under 100 in literary works), while journalistic and technical writing often uses digits for anything 10 and above. Always check your specific style manual.
How can I easily remember the correct spelling?
Associate the word with words like for or port. If it helps, remember that you are dropping the u to make typing faster—four letters vanish down to three consonants surrounding the vowel.
