To say something is “too much” or “too small” or that we drank “too much” and so forth, we use the verb 過ぎる.
Adjectives
For i-adjectives we remove the い and add すぎる.
高すぎる。
Too high/expensive.
Once すぎる is attached, the entire word functions as a regular Group 2 (ru-verb). This means you can conjugate it into the te-form (すぎて), past tense (すぎた), or polite form (すぎます). Note that the subject of the adjective still takes the が particle.
怖すぎる。
Too scary.
映画が怖すぎて、最後まで見られなかった。
The movie was too scary so I couldn’t watch until the end.
パソコンが高すぎて買いませんでした。
The computer was too expensive so I didn’t buy it.
For na-adjectives we just add すぎる without the auxiliary verb or な particle.
複雑すぎる。
Too complicated.
この数学の問題が複雑すぎるから、明日は先生に聞きます。
This math problem is too complicated so I’ll ask the teacher tomorrow.
Verbs
For verbs we need to use the verb stem.
昨日は飲み過ぎて、頭が痛いですよ。
I drank too much yesterday—my head hurts!
Exceptions (Important for JLPT)
There are two highly common irregulars that frequently appear as trick questions on the JLPT. For いい (good) and ない (not), an extra さ is added before すぎる.
このパソコンは良さすぎる。
This computer is too good.
時間がなさすぎる。
There is too little time. (Literally: There is too much of “no time”).