Look at the Ending First
When conjugating Korean verbs and adjectives, do not try to analyze everything about the stem at once.
Instead, look at the ending you want to attach first. The ending tells you exactly what information you need to find in the stem.
By building the habit of looking at the ending first, you can skip unnecessary steps and conjugate much faster.
Group 1: Attach Directly
Some endings do not care about the stem's vowels or bottom consonants (batchim). You simply remove -다 and attach them directly.
Examples include -고 (and) and -지만 (but).
Dictionary Form · -고 Form · -지만 Form
가다 · 가고 · 가지만
먹다 · 먹고 · 먹지만
크다 · 크고 · 크지만
You do not need to check anything else before attaching these.
Group 2: Check for Batchim
Other endings only care if the stem has a final consonant (batchim). They do not care about which vowel is used.
Examples include -으면/면 (if) and -을/ㄹ (future/modifier).
If there is a batchim: use the longer form (으면, 을).
If there is no batchim: use the shorter form (면, ㄹ).
Dictionary Form · Batchim? · Conjugated Form
찾다 · Yes · 찾으면
자다 · No · 자면
입다 · Yes · 입을 거예요
보다 · No · 볼 거예요
Group 3: Check the Last Vowel
The final group of endings needs to know the last vowel of the stem. They do not care if there is a batchim or not.
Examples include -아요/어요 (polite present) and -았/었- (past tense).
If the last vowel is ㅏ or ㅗ: choose 아요.
Otherwise: typically choose 어요.
Dictionary Form · Last Vowel · Conjugated Form
받다 · ㅏ · 받아요
적다 · ㅓ · 적어요
오다 · ㅗ · 왔어요
마시다 · ㅣ · 마셨어요
Common Mistake: Mixing the Rules
A very common beginner mistake is applying the vowel rule to an ending that just attaches directly.
Mistake: 먹어고 (X)
Correct: 먹고 (O)
Because 먹다 becomes 먹어요, learners sometimes try to add that extra "어" to everything. Remember that -고 is a Group 1 ending. It attaches directly to the stem without any extra vowel changes.
Quick review
Do not over-conjugate
Match the rule to the ending