Korean Verb Conjugation Rules, Step by Step

In Korean, verbs change their ending to show the tense (past, present or future) and how polite you’re being with the person you’re talking to. This is called conjugation. So if you want to say “I sleep,” for example, you can’t use the dictionary form 자다 (jada) and have to change it to 자요 (jayo) instead.

In this post I’ll explain how to make the polite present form, the one that ends in 요 (yo), because it’s the form you’ll use most with people you don’t know well. After that, I’ll also cover the past tense, like 잤어요 (jasseoyo, I slept), the future, like 잘 거예요 (jal geoyeyo, I’ll sleep), and the casual and formal ways of speaking.

The tricky part about conjugation is that the ending doesn’t always look the same. For example, 먹다 (meokda, to eat) becomes 먹어요 (meogeoyo), but 가다 (gada, to go) becomes 가요 (gayo), and 마시다 (masida, to drink) becomes 마셔요 (masyeoyo). If you look at the vowel right before 요, it’s different each time: ㅓ (eo) in 먹어요, ㅏ (a) in 가요, and ㅕ (yeo) in 마셔요. That’s because the vowel depends on the last vowel of the verb, so once you know how that works, you can conjugate any regular verb.

Some verbs don’t follow these rules, though. They’re called irregular verbs, and I’ll show you how to handle them at the end of the post.

Step 1: Drop 다 to get the stem

Every Korean verb you look up in the dictionary ends in 다 (da). This is called the dictionary form, and you won’t hear it much in conversation. To conjugate a verb, you first take 다 off, and what’s left is called the stem. Every ending in this post gets added to it.

The last one in the table, 좋다 (jota), is actually an adjective, but that doesn’t change anything here, because for every form in this post, Korean adjectives take the same endings as verbs. So 좋다 works the same way as 먹다 (meokda).

Step 2: Pick 아요 or 어요

Once you have the stem, you need to decide whether to add 아요 (ayo) or 어요 (eoyo), and for that you look at the vowel in the last syllable of the stem:

Keep in mind that only the last syllable counts. In 마시다 (masida, to drink), for example, the stem is 마시 (masi). The first syllable has ㅏ, but the one you check is 시, which has ㅣ, so it takes 어요.

The one big exception is 하다 (hada, to do). It doesn’t follow this rule at all and always becomes 해요 (haeyo). You’ll use it constantly, because lots of verbs end in 하다: 공부하다 (gongbuhada, to study) becomes 공부해요 (gongbuhaeyo), and 일하다 (ilhada, to work) becomes 일해요 (ilhaeyo).

Step 3: When two vowels meet

This is the step that confuses most people, and what happens depends on how the stem ends. If its last syllable ends in a consonant, which is called batchim (받침), you just add the ending after it. But if it ends in a vowel, that vowel and the 아 or 어 usually combine into one syllable:

Because 가 already ends in ㅏ, the extra 아 merges into it. The table below shows what happens with each vowel.

The last row works a bit differently. When the stem ends in ㅡ, the ㅡ drops out, and then you choose 아 or 어 by looking at the syllable before it. So 바쁘다 (bappeuda, to be busy) becomes 바빠요 (bappayo), because the syllable before ㅡ has ㅏ. If the stem has only one syllable, like 쓰 (sseu), there’s nothing before it, so it takes 어 and becomes 써요.

One combination in the table causes more mistakes than the others: 되 + 어. The result is 돼요 (dwaeyo), since 돼 is just 되어 written as one syllable, the same way 해 comes from 하여. But because 되요 and 돼요 sound almost the same, a lot of people write 되요 by mistake, and even Korean speakers do it online.

To check which one is right, replace 되 with 하 and 돼 with 해 in the word you want to write, and see which version is correct. For 되요 and 돼요, you’d get 하요 and 해요. Nobody says 하요, but 해요 is correct, so the right spelling is 돼요. The same check works with other endings too. If you’re not sure whether to write 되니까 or 돼니까 (doenikka, because it becomes), you’d get 하니까 and 해니까. This time 하니까 is the correct one, so you write 되니까.

Step 4: The past and the future

For the past tense, you make the same 아/어 choice as in step 2, but this time you add 았 (at) or 었 (eot) to the stem and then 어요 (eoyo) after it:

As you can see with 갔어요, the vowels combine the same way as in step 3, so 가 + 았 becomes 갔. Here are a few more verbs in the present and the past:

So if you already know the present form, there’s a quick way to get the past: take 요 off, add ㅆ to the last syllable, and then add 어요. For example, 가요 becomes 가, then 갔, and then 갔어요 (gasseoyo).

The future is easier, because the 아/어 choice doesn’t matter there. Instead, the ending depends on whether the stem has batchim, and stems that already end in ㄹ, like 살다 (salda, to live), don’t need another ㄹ:

Step 5: Casual, polite and formal

The 요 form you’ve been making so far is the polite one, but Korean has two other common levels, and you can get both of them from what you already know.

To speak casually, you take 요 off the polite form, so 먹어요 becomes 먹어 and 가요 becomes 가. (This works for verbs. 이에요 (ieyo, to be) follows its own rule, so I’ll leave it for another post.) The formal level works differently, because it doesn’t use 아/어 at all. Instead, it depends on batchim again, and this time a stem ending in ㄹ loses its ㄹ:

Verbs that don’t follow these rules

Everything above works for most verbs. However, a smaller group changes its stem or ending when you add an ending that starts with a vowel, like 아요/어요, 았/었 or 을 거예요, so if you follow the steps above with them, you get a form that looks right but isn’t.

These are called irregular verbs. They fall into seven main groups, and the verbs in each group change in the same pattern, so you can learn them group by group. I’ve put all of them on one page, together with the common verbs in each group and the verbs that look irregular but aren’t: Korean irregular verbs.

To sum up, conjugating a regular verb comes down to three things: take 다 off to get the stem, look at the last vowel to choose 아 or 어, and combine the vowels where they meet. Some verbs will still make you hesitate at first, but most of the time it’s one of the combinations from step 3, and with practice you’ll start recognizing them without thinking.

Which verbs do you still find hard to conjugate? Look one up in the irregular verbs list and see which group it belongs to.