予定(よてい)だ is an expression that functions very similarly to
つもりだ ‘to intend to do’. The primary difference being that 予定(よてい) is a ‘plan’, rather than an ‘intention’. Due to this,
予定(よてい) is used far more frequently for things that you have formal plans to do (like meeting a friend for lunch).
To use
予定(よてい), just attach it to the non-past form of a verb, or to a noun (after inserting
の).
-
今夜(こんや)は先輩(せんぱい)たちと飲(の)みに行(い)く予定(よてい)だ。
I plan to go drink with my senpai tonight.
-
休(やす)みは来週(らいしゅう)からの予定(よてい)だ。
My break is planned to start from next week.
If
だ or
です is not added after
予定(よてい), it will imply that
予定(よてい) is simply modifying the verb/noun that comes before it, rather than being a standalone ‘plan’. This is similar to the difference between saying something like ‘I have plans to eat with a friend’ (natural), vs ‘I have an eating with a friend plan’ (unnatural).
-
明日(あした)は友達(ともだち)とステーキを食(た)べる予定(よてい)だ。
I have plans to eat a steak with a friend tomorrow. (Natural Japanese)
-
明日(あした)は友達(ともだち)とステーキを食(た)べる予定(よてい)。
I have an ‘eating a steak with a friend’ plan tomorrow. (Unnatural Japanese)