Verbseoul.
하다 verb

확신하다 conjugation (hwaksinhada, to be convinced, to be sure, to be certain)

To say to be convinced, to be sure, to be certain politely in the present tense, use 확신해요 (hwahg-sheen-hae-yoh) · hwakssinhaeyo. Below is the full conjugation of 확신하다 across the three tenses and three everyday speech levels.

Grammar note (하다 verb): 하다 verbs are formed with a Sino-Korean noun + 하다 (e.g. 공부하다 = study + do). 하다 conjugates irregularly: the ㅏ in 하 contracts with the -아/-어 suffix to give 해 (not *하어). Present polite: 해요; past polite: 했어요. The formal ending is 합니다 (not *하습니다). Most noun+하다 compounds follow this pattern uniformly. See all 하다 verbs →

Conjugation table

pron. = pronunciation guide  · RR = Revised Romanization

Highlighted = where the stem changes

TenseCasual (반말)Polite (요)Formal (합니다)
Present
확신해
hwahg-sheen-hae
hwakssinhae
확신해요
hwahg-sheen-hae-yoh
hwakssinhaeyo
확신합니다
hwahg-sheen-hahm-nee-dah
hwakssinhamnida
Past
확신했어
hwahg-sheen-hae-ssuh
hwakssinhaesseo
확신했어요
hwahg-sheen-hae-ssuh-yoh
hwakssinhaesseoyo
확신했습니다
hwahg-sheen-hae-sseum-nee-dah
hwakssinhaesseumnida
Future
확신할 거야
hwahg-sheen-hahl guh-yah
hwakssinhal geoya
확신할 거예요
hwahg-sheen-hahl guh-yae-yoh
hwakssinhal geoyeyo
확신할 겁니다
hwahg-sheen-hahl guhm-nee-dah
hwakssinhal geomnida

Other useful forms

Honorific / Command Polite (-(으)세요)
확신하세요
hwahg-sheen-hah-sae-yoh
hwakssinhaseyo
Suggestion / Let's Polite (요)
확신해요
hwahg-sheen-hae-yoh
hwakssinhaeyo
Question Polite (요)
확신해요?
hwahg-sheen-hae-yoh-?
hwakssinhaeyo?
Connective "and" — (고)
확신하고
hwahg-sheen-hah-goh
hwakssinhago
Conditional "if" — (면)
확신하면
hwahg-sheen-hah-myuhn
hwakssinhamyeon
Progressive (고 있어요)
확신하고 있어요
hwahg-sheen-hah-goh ee-ssuh-yoh
hwakssinhago isseoyo
Want to (고 싶어요)
확신하고 싶어요
hwahg-sheen-hah-goh shee-puh-yoh
hwakssinhago sipeoyo
Can / Able to ((으)ㄹ 수 있어요)
확신할 수 있어요
hwahg-sheen-hahl soo ee-ssuh-yoh
hwakssinhal su isseoyo
Because / So (아/어서)
확신해서
hwahg-sheen-hae-suh
hwakssinhaeseo
Noun form — (기)
확신하기
hwahg-sheen-hah-gee
hwakssinhagi
Noun form — (음)
확신함
hwahg-sheen-hahm
hwakssinham