How to say "forty" in Japanese

• ４０よんじゅうCommon
  numeralThe common way to write and say the number forty, read よんじゅう. For the number itself—in counting, ages, prices and the like—this is the word you will almost always want.
  アインシュタインが死しんでからほぼ四十よんじゅう年ねんになる。↗

  Einstein has been dead for nearly forty years.
• フォーティー
  nounThe English loanword in katakana. Much less common than ４０, it is seldom the word you want for the number itself; it turns up mainly where English usage is being echoed.

For the number forty itself, use ４０（よんじゅう）, the common form; 「フォーティー」 is simply the English loanword in katakana, much less common, and seldom the word you actually need.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• ４０よんじゅうforty
• フォーティーforty