What Is a Run-on Sentence?

A run on sentence can disrupt the flow of your writing, whether it’s in an academic paper or just an email. A run on sentence is essentially a punctuation error, and can usually be fixed by adding a period, semi-colon or other punctuation.


A run on sentence is when two sentences are joined together without proper punctuation or any sort of conjunction (and, but, yet, etc.). Like the name implies, the words simply run together, because there is not the proper punctuation to separate the independent clauses (clauses that can stand alone). A run on sentence does not have to be long, and likewise, a very long sentence does not mean it is a run on. Run on sentences are also commonly called fused sentences.

Comma Splice

A run on sentence often happens when there is no punctuation to join two independent clauses together. The writing error can also occur when only a comma is used to join two independent clauses together. This is known as a comma splice and is the most common type of run on. A comma can be used to join independent clauses, but there typically needs to be a conjunction in there as well, such as “and,” “but,” “yet” and so on.


Here are some run on sentences where independent clauses simply run together: “He is a tall boy he is 7 feet tall.” The two independent clauses are “He is a tall boy” and “He is 7 feet tall.” Thus, you need some sort of conjunction or punctuation between those. Another example: “The cookies were very burnt I shouldn’t have cooked them so long.” The two independent clauses are “The cookies were very burnt” and “I shouldn’t have cooked them so long.” Again, you need a conjunction or punctuation between the thoughts. However, in both these examples, you’d be making a comma splice if you simply put a comma between the independent clauses, such as, “He is a tall boy, he is 7 feet tall” or “The cookies were very burnt, I shouldn’t have cooked them so long.”

How to Fix

It can vary case by case, but typically a run on sentence is missing correct punctuation or a conjunction. Common punctuation is a period or semi-colon between the two independent clauses, as adding a comma alone will only create a comma splice. Common conjunctions are “and” and “but.” Looking at the examples above, you can fix those run on errors by adding the appropriate punctuation. First, a semi-colon: “He is a tall boy; he is 7 feet tall.” As well, you can use a period: “He is a tall boy. He is 7 feet tall.” In this case, using a conjunction might sound awkward, simply because of how the sentence is worded. For the other example, you can use a semi-colon: “The cookies were very burnt; I shouldn’t have cooked them so long.” You can also use a period: “The cookies were very burnt. I shouldn’t have cooked them so long.” And finally, a conjunction doesn't sound awkward in this case. In particular “so” works well. “The cookies were very burnt, so I shouldn’t have cooked them so long.”

About the Author

Chris Brower is a writer with a B.A. in English. He also spent time studying journalism and utilizes both to deliver well-written content, paying close attention to audience, and knowing one word could determine whether a product is a success or a failure. He has experience writing articles, press releases, radio scripts, novels, short stories, poems and more.

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