How do you say “I’m hungry” in Japanese?

When you want to say “I’m hungry” in Japanese, you can say,

おなかすいた
Onaka suita : casual form

おなかがすきました
Onaka ga sukimashita : polite form

When you want to ask someone “are you hungry?, you can say the same phrase ending with upper intonation.

おなかすいた?
Onaka suita?

Are you hungry?

ちょっと
Chotto

A little.

Or you can add “ka” to make a question.

おなか、すきましたか?
Onaka, sukimashita ka?

Are you hungry?

いえ、大丈夫(だいじょうぶ)です。
Ie, daijoobu desu.

No. I’m OK.

On the other hand, if you want to say “I’m full”, you can say,

おなか(が)、いっぱい(です)
Onaka (ga) ippai (desu)

I’m full.

Onaka means “belly” or “stomach”, so “onaka ga ippai desu” literally means “my stomach is full”.