Verbseoul.
하다 verb (adj)
잔잔하다janjanhadacalm

To say calm politely in the present tense, use 잔잔해요 (chahn-chahn-hae-yoh). Below is the full conjugation of 잔잔하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
잔잔해
chahn-chahn-hae
잔잔해요
chahn-chahn-hae-yoh
잔잔합니다
chahn-chahn-hahm-nee-dah
Past
잔잔했어
chahn-chahn-hae-ssuh
잔잔했어요
chahn-chahn-hae-ssuh-yoh
잔잔했습니다
chahn-chahn-hae-sseum-nee-dah
Future
잔잔할 거야
chahn-chahn-hahl- -guh-yah
잔잔할 거예요
chahn-chahn-hahl- -guh-yae-yoh
잔잔할 겁니다
chahn-chahn-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
잔잔하세요
chahn-chahn-hah-sae-yoh
Suggestion / Let's Polite (요)
잔잔해요
chahn-chahn-hae-yoh
Question Polite (요)
잔잔해요?
chahn-chahn-hae-yoh-?
Connective “and” — (고)
잔잔하고
chahn-chahn-hah-goh
Conditional “if” — (면)
잔잔하면
chahn-chahn-hah-myuhn
Noun form — (기)
잔잔함
chahn-chahn-hahm