Expressing Reasons with -(으)니까
The connecting ending -(으)니까 links two sentences by showing that the first sentence is the reason or basis for the second sentence.
It is often translated as "because" or "since." It is especially common when the speaker is providing a justification for a suggestion or a command that follows.
Form Rules: -니까 vs -으니까
The form you use depends on whether the verb or adjective stem ends in a consonant (batchim).
No batchim (vowel)
Add -니까 (가다 → 가니까).
Batchim (consonant)
Add -으니까 (먹다 → 먹으니까).
Stem · Ending · Connected Form
가다 · -니까 · 가니까
먹다 · -으니까 · 먹으니까
Core takeaway: How to attach the ending based on the final consonant.
Perfect for Suggestions and Commands
One of the most important features of -(으)니까 is that it works perfectly with suggestions, requests, and commands. If your second sentence ends in "let's do..." or "please do...", this is the connector you want.
비가 오니까 우산을 가져가세요 . (Since it is raining, please take an umbrella.)
날씨가 좋으니까 같이 걸어요 . (Since the weather is good, let's walk together.)
Using Past Tense with -(으)니까
Unlike some other reason connectors, you can attach past tense markers (like -았/었- ) directly before -(으)니까 to express a reason based on something that already happened.
Past Tense Stem
늦다 → 늦었- → 늦었으니까
늦었으니까 택시를 타요. (Since we are late, let's take a taxi.)