해야해요 vs 해야돼요 in Korean

Hi guys, it’s your Korean teacher Jun! Today I’ve got a question from Nati of Korean Jun Club members. The question is : what’s different between 해야 해요 and 해야 돼요? It’s a very great question and also quite tricky to answer lol. But today I’m going to make a perfect explanation for 해야해요 vs 해야돼요!

Warm Up Your Brain

What things do you have to do everyday? Read 해야해요 and 해야돼요 loud while you are thinking about things you have to do.

해야 해요 Meaning in Korean

-야 해요

[ya heyo]
Have to / Should / Must

Basic form : 해야 하다
반말(informal non-honorific) form : 해야해
Negative form with 해요 speech style : 안해도

First, I’ll explain about 해야 해요. 해야 해요 is the most basic phrase to make an obligation sentence in Korean grammar. It’s same to ‘have to’, ‘should’ and ‘must’ in English. Also, 해야 해요 is a conjugation so you have to attach it behind a verb stem to use.

The National Institute of The Korean Language defines 해야 해요 describes a necessity to do or be.

식당은 늘 청결해야 한다
[sikdang-eun neul cheonggyeol-heya handa]
Restaurants must be always clean

Have To in Korean

-야 돼요

[ya doeyo]
Have to / Should / Must

Basic form : 해야 되다
반말(informal non-honorific) form : 해야돼
Negative form with 해요 speech style : 안해도 돼요

Basically, 해야 돼요 doesn’t make a big difference. It means ‘have to’, ‘should’ or ‘must’ but it’s much more common in any casual conversation. It’s used to make an obligation sentence as a conjugation. Besides a slightly difference of nuance between 해야 해요 and 해야 돼요, those are almost same.

The National Institute of The Korean Language defines 해야 돼요 describes something has to happen or become.

저는 청소해야 돼요
[jeo-neun gongbu-heya doeyo]
I have to clean (my room)

해야해요 vs 해야돼요

So, 해야해요 sounds more formal and is used for something needs a formal speech. And 해야돼요 is more common in casual conversation. Then is 해야 돼요 informal? Nope, 해야돼요 can be used in a formal speech and an informal speech both.

You can can find 해야해요 mostly in something that needs a formal speech such as report, news, laws, instructions, rules, regulations and quotes especially with 하다 speech style (basic speech style).

Since 해야해요 means something has to happen or become, it sounds like future related sometimes.

돼요 Verb Conjugation

돼요 is a verb conjugation that means soooo many things and it has a big role in Korean grammar. 돼요 literally means ‘to become’, ‘to happen’. Think about an English word ‘get’. It might be able to help you understand 돼요. 

돼요 has some grammatical functions. When you say ‘will be + noun’ like ‘I’ll be a teacher’, You have to use 돼요 verb.

선생님이 될거예요
I’ll be a teacher

돼 vs 되

돼요 actually has 2 spellings. Same word, same meaning but 2 different way to spell. Both are same. 돼 is a shortened form of ‘되어’.

되었다 = 됐다
되어요 = 돼요

Vocabulary Note

식당 [sikdang] : restaurant
늘 [neul] : always (same old)
청결하다 [cheongyeol-hada] : be clean [forma]
청소하다 [cheongso-hada] : to clean
선생님 [seonseng-nim] : teacher