A run-on sentence isn't just a long sentence. It's two (or more) complete sentences squeezed together without the punctuation that should separate them.
What is a run-on sentence? #
I finished the report I sent it to my manager.
I finished the report and I sent it to my manager are both complete sentences. Nothing separates them, so the reader stumbles.
A close cousin is the comma splice, where only a comma joins the two sentences. Read what a comma splice is.
Long doesn't mean run-on #
This long sentence is not a run-on, because it's correctly joined:
Although the deadline was tight and the team was small, we finished the report, checked every number, and sent it to the client before noon.
4 ways to fix a run-on #
1. Add a period.
I finished the report. I sent it to my manager.
2. Add a semicolon.
I finished the report; I sent it to my manager.
3. Add a comma and a conjunction (and, but, so, or, yet).
I finished the report, and I sent it to my manager.
4. Rewrite so one part depends on the other.
After I finished the report, I sent it to my manager.
How to spot one #
Read the sentence and look for the place where a new subject and verb start (I sent, she said, it was). If nothing separates it from the part before, you've found a run-on.
Common run-on patterns #
| Run-on | Fixed |
|---|---|
| It's late. We should go. | |
| I called her, but she didn't answer. | |
| The app is great; I use it daily. |
Let AI untangle it #
AI Grammar Checker finds run-on sentences and splits or joins them correctly, and checking again gives you a smoother paraphrase.