What Is a Comma Splice? Four Ways to Fix One

What it looks like

A comma can join many things, but it cannot join two sentences on its own.

• ✗ The report is due Friday, I haven’t started it.
• ✗ It was late, however we kept working.

Each side of the comma is a complete sentence — an independent clause, with its own subject and verb. A comma between them is too weak a joint, and the reader briefly loses track of where one thought ends.

Four ways to fix it

Take the sentence The report is due Friday, I haven’t started it.

1. A full stop. The simplest fix. The report is due Friday. I haven’t started it.

2. A semicolon. When the two thoughts are closely linked. The report is due Friday; I haven’t started it.

3. A comma plus a joining word. Use one of and, but, or, nor, for, so, yet. The report is due Friday, but I haven’t started it.

4. Make one half depend on the other. Add a word like although, because, since, when or while. Although the report is due Friday, I haven’t started it.

Each fix gives a slightly different emphasis. Option 3 with but stresses the contrast; option 4 makes the deadline background to the main point.

The however trap

Words like however, therefore, moreover and consequently are not joining words in the way but and so are. A comma before them still leaves a splice.

• ✗ It was late, however we kept working.
• ✓ It was late; however, we kept working.
• ✓ It was late. However, we kept working.

When it is allowed

In fiction and informal writing, short parallel clauses are sometimes spliced on purpose for rhythm: I came, I saw, I conquered. That is a deliberate choice. In essays, reports and professional email, readers will read it as an error, so use one of the four fixes.

How to find them

Comma splices often hide in long sentences. Any sentence over about 30 words is worth checking — the readability checker lists them for you.