How to say "crucial" in Japanese

• 大事だいじJLPT N4approx.Common
  na-adjectiveCovers crucial in the sense of serious and consequential: a matter whose outcome carries real weight. Often used of situations and decisions where getting things wrong would matter greatly.
• 肝心かんじんJLPT N1approx.Common
  na-adjective, no-adjectiveCovers crucial in the sense of being the point everything hinges on: the essential part among others. Use it when singling out what really counts, such as the key step of a plan.
  なんであれ物事ものごとの本体ほんたいを捕とらえる事ことが肝心かんじんだ。↗

  No matter what the problem is, it's essential to get at the heart of the matter.
• 大切たいせつJLPT N5approx.Common
  na-adjectiveCovers crucial only weakly; its core sense is important and significant, especially for things one treasures or must handle with care. For abstractly crucial matters it works, but it often sounds more like 'important' or 'precious'.
  柔道じゅうどうでは力ちからより技わざのほうが大切たいせつである。↗

  In judo, technique is more important than strength.
• 肝要かんようCommon
  na-adjective, nounCovers crucial as extremely important and vital, with a formal, written flavor. Suits emphatic statements that something is absolutely essential to success, as in exhortations or instructions.
  危機ききの際さいにも冷静れいせいさを失うしなわず、狂気きょうきに走はしるのを避さけることが肝要かんようである。↗

  It is essential to keep calm in a time of crisis and avoid going haywire.

Choose 大切 for things that matter personally, 大事 for serious or weighty matters, 肝心 for the point on which success hinges, and 肝要 for what is absolutely essential.

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

• 大事だいじimportant
• 肝心かんじんessential
• 大切たいせつimportant
• 肝要かんようextremely important
• 肝心要かんじんかなめcrucial
• 核心的かくしんてきcrucial
• 欠かせないかかせないindispensable