How do you fix a comma splice?

Use a period ("I was tired. I went to bed."), a semicolon ("I was tired; I went to bed."), or a comma plus a coordinating conjunction such as and, but or so ("I was tired, so I went to bed.").

Is a comma before "however" a comma splice?

Yes, when "however" joins two complete sentences. "The test was hard, however, I passed" is a splice; write "The test was hard; however, I passed."

What is the difference between a comma splice and a run-on sentence?

A comma splice joins two sentences with only a comma. A fused (run-on) sentence joins them with no punctuation at all. Both are fixed the same way.

What Is a Comma Splice? Examples and 3 Ways to Fix It

Q: What is a comma splice?

A comma splice is two complete sentences (independent clauses) joined by only a comma, such as "I was tired, I went to bed."

Grammar rules

Short answer: a comma splice is two complete sentences joined by nothing but a comma, like "I was tired, I went to bed." Fix it by using a period, a semicolon, or a comma plus a conjunction such as and, but or so: "I was tired, so I went to bed."

A comma splice happens when two independent clauses (each one able to stand alone as a sentence) are joined with only a comma. A comma isn't strong enough to do that job on its own, which is why splices read as rushed or run-on even when every word is spelled correctly.

✗ I finished the report, I sent it to my manager.
✓ I finished the report, and I sent it to my manager.

Comma splice examples and fixes

✗ It was raining, we stayed inside. → ✓ It was raining, so we stayed inside.
✗ She loves coffee, she drinks it every morning. → ✓ She loves coffee; she drinks it every morning.
✗ The meeting ran late, I missed my train. → ✓ The meeting ran late. I missed my train.
✗ The test was hard, however, I passed. → ✓ The test was hard; however, I passed.

The last one is the most common splice in professional writing. Words like "however," "therefore" and "moreover" are not conjunctions, so a comma before them still leaves a splice. See how to punctuate conjunctive adverbs.

How to tell if you have one

Check whether the text on either side of the comma could stand alone as its own sentence. If both halves make complete sense by themselves ("I finished the report." and "I sent it to my manager."), a lone comma between them is a splice.

Three ways to fix a comma splice

Add a coordinating conjunction after the comma: and, but, or, so, yet, for, nor.
I finished the report, so I sent it to my manager.
Replace the comma with a semicolon if the two ideas are closely related.
I finished the report; I sent it to my manager.
Split it into two sentences with a period.
I finished the report. I sent it to my manager.

A fourth option is to make one clause depend on the other: "After I finished the report, I sent it to my manager."

Comma splice vs. run-on (fused) sentence

Both join two complete sentences incorrectly. A comma splice uses only a comma; a fused sentence uses no punctuation at all ("I finished the report I sent it to my manager"). Many teachers call both of them run-on sentences, and the fixes are the same.

When a comma splice is actually fine

Short, punchy, parallel clauses in informal or literary writing sometimes use splices deliberately for rhythm. "I came, I saw, I conquered" is technically a comma splice, and nobody minds. The rule matters most in formal, academic and professional writing, where a splice reads as a mistake rather than a stylistic choice.

Why this is easy to miss in your own writing

Comma splices often happen when you're writing quickly and the two ideas feel connected in your head, so the pause of a comma feels sufficient even though grammatically it isn't. Proofread Bot checks sentence structure directly rather than how the sentence "feels," so it flags splices and suggests a fix.

Check your writing for comma splices →