How to say "beforehand" in Japanese

• あらかじめJLPT N1approx.Common
  adverbThe all-purpose adverb for 'beforehand': an action — telling, preparing, arranging — is done ahead of time. It fits most sentences where English simply says 'beforehand' or 'in advance'.
  私わたしたちはあらかじめスナックを用意よういしておいた。↗

  We prepared snacks beforehand.
• 事前じぜんJLPT N1approx.Common
  no-adjectiveA noun covering 'prior' and 'before the fact' — think of arrangements made prior to an event. It behaves like English 'prior to', not like the adverbs あらかじめ and 前もって.
  事前じぜんに予約よやくを取とっておくべきだ。↗

  We'd better make a reservation beforehand.
• 前もってまえもってJLPT N1approx.Common
  adverbAlso an adverb, 'in advance; beforehand', and in most sentences interchangeable with あらかじめ; either works when you say you did or arranged something ahead of time.
  私は前まえもってあなたに知しらせる。↗

  I will let you know in advance.

Use the adverbs 「あらかじめ」 and 「前もって」, largely interchangeable, for an action done in advance, and the noun 事前 where English would say 'prior to' or 'before the fact'.

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

• あらかじめbeforehand
• 事前じぜんprior
• 前もってまえもってin advance
• 前広まえびろprevious
• かねてよりpreviously
• 先にさきにbeforehand