Forty vs. Fourty: Which Spelling Is Correct?

Forty is the only correct spelling of the number 40. Fourty is a common misspelling and is not accepted in American or British English, in any context.

Why People Get Confused

The confusion makes sense once you look at the word closely. The number 4 is spelled four, with a “u.” Other related numbers keep that “u” too: fourteen and fourty-four look like they should follow the same pattern. So writers naturally assume forty should have a “u” in it as well. It doesn’t, and there’s a historical reason why.

The Correct Spelling: Forty

Forty is the standard, dictionary-approved spelling of the number 40 in every English-speaking country, including the United States, the United Kingdom, Canada, and Australia. Unlike some words that split into American and British variants (think color vs. colour), forty has no regional alternative. There is exactly one accepted spelling, and it’s forty.

Correct examples:

• She turned forty last week.
• The speed limit here is forty miles per hour.
• He has forty dollars left in his wallet.
• The team signed forty new players this season.

Where “Fourty” Comes From

Fourty isn’t a modern typo invented by autocorrect. According to Merriam-Webster, the word traces back to Middle English fourty, which itself descended from Old English fēowertig, a combination of fēower (four) and -tig (a suffix meaning “a group of ten”). So the “u” was there originally, tied directly to the spelling of four.

Over the centuries, English spelling standardized, and the “u” was dropped from the tens-place word while it stayed in four, fourteen, and fourth. Merriam-Webster records the word’s first known use as before the 12th century, but the modern spelling forty is what dictionaries and style guides recognize today. Fourty survives only as a historical spelling variant, not as an accepted modern form.

Forty Is the Odd One Out

Here’s the part that trips people up: forty is the only number in the tens sequence where the base number’s spelling doesn’t carry over cleanly.

Base Number	Tens Word	Spelling Pattern
Two	Twenty	Keeps “tw” from two
Three	Thirty	Changes to “thir-“
Four	Forty	Drops the “u” from four
Five	Fifty	Changes to “fif-“
Six	Sixty	Keeps “six” exactly
Seven	Seventy	Keeps “seven” exactly
Eight	Eighty	Keeps “eight” exactly
Nine	Ninety	Keeps “nine” exactly

Notice that thirty and fifty also change their base spelling (three → thir-, five → fif-), so forty isn’t entirely alone in breaking the pattern. But because four and fourteen both keep the “u,” forty’s missing “u” stands out more and causes more spelling mistakes than thirty or fifty ever do.

Fourty in Compound Numbers

The same rule applies when forty is part of a larger number. Whether you’re writing forty-one or forty-nine, the spelling never reverts to “fourty.”

Correct:

• forty-one
• forty-five
• forty-eight
• one hundred forty

Incorrect:

• fourty-one
• fourty-five
• fourty-eight
• one hundred fourty

Common Mistakes to Watch For

Mistake	Why It Happens	Correction
Fourty	Writer assumes it follows “four”	Forty
Fourty-two	Same error carried into compound numbers	Forty-two
Forty vs. fourty in formal writing	Spellcheck sometimes misses it in casual typing apps	Always double-check with a dictionary
Confusing forty with fourteen	Both start with “four-” sounds when spoken quickly	Forty = 40, Fourteen = 14

Spellcheck tools in most word processors will flag fourty as an error, but the mistake still slips through in text messages, social media posts, and quickly typed emails where autocorrect is turned off or ignored.

A Simple Trick to Remember It

If you need a quick way to lock in the correct spelling, try this: forty rhymes with “naughty,” and neither word has a “u” in it. Picture the phrase “forty is naughty” (because it drops the “u”) and the spelling should stick.

Another option is to remember that forty is the exception, not the rule. Since four, fourteen, and fourth all keep the “u,” forty is the one number in that family that breaks away from it. Once you’ve memorized that forty is the odd one out, the spelling becomes easier to recall.

Forty in Real-World Use

News outlets and major publications consistently use forty, never fourty, which reflects the standard across professional writing:

• “The site has about forty full-time employees, mostly in New York, where the publication is based.” — The New Yorker
• Sports and lifestyle writing frequently reference people “in their forties,” never “fourties.”

If a spelling doesn’t appear in edited, professionally published writing, that’s usually a strong sign it isn’t standard English, and fourty fits that pattern exactly.

Frequently Asked Questions

Is fourty ever correct in British English?

No. Unlike some words with US/UK spelling differences, forty has no British variant. Fourty is incorrect in both American and British English.

Why does four have a “u” but forty doesn’t?

Historical spelling evolution dropped the “u” from forty over time, even though it was present in the Old English and Middle English ancestors of the word. Four, fourteen, and fourth kept the “u,” but forty did not.

Is “forty” the same in Canadian and Australian English?

Yes. Forty is standard across all major English-speaking countries, including Canada and Australia. There is no regional variant that uses fourty.

How do I remember not to write fourty?

Associate forty with “naughty.” Both words drop the “u” and end the same way, which makes the correct spelling easier to recall.

Is fourty a word at all?

No. Fourty is not a recognized word in current English dictionaries. It only appears historically, as an older spelling variant that fell out of use centuries ago.

Bottom Line

Forty is correct. Fourty is not, no matter the context, region, or number combination it’s part of. The confusion comes from four’s spelling carrying a “u” that forty simply doesn’t share. Once you remember that forty is the exception among the tens-place numbers, the correct spelling becomes second nature.

Read more: Fourteen or Forteen: The Complete Spelling Guide