Comma splices

The rule in one minute

A comma splice happens when two complete sentences are joined by only a comma. Each part has its own subject and verb, so each could stand alone.

The bus was late, we missed the film. This is a comma splice. The bus was late is a sentence. We missed the film is also a sentence. A comma is only a small pause, so it cannot join them.

The mistake is tempting because the two ideas are related, and a full stop can feel too strong. But related ideas still need a proper join.

If you can see that both sides of the comma are full sentences, you have found a splice. Then you only need to choose a fix.

Why it costs marks

Markers use sentence boundaries to judge accuracy. If boundaries keep failing, the accuracy mark cannot reach the top bands.

In ESL writing, correctness is marked directly, and the splice is one of the errors markers spot fastest. It rarely happens once. A student who splices tends to do it all through an answer.

The rule is clear, so this is one of the most satisfying errors to remove.

Four ways to fix it

Take the splice The sky darkened, the match was abandoned.

• Full stop: The sky darkened. The match was abandoned. This is cleanest when the ideas are separate.
• Semicolon: The sky darkened; the match was abandoned. Use this when the ideas are closely linked.
• Comma plus a joining word: The sky darkened, so the match was abandoned. The joining words are and, but, or, so, yet, for, nor.
• Dependent clause: Because the sky darkened, the match was abandoned. This also shows which idea depends on the other.

More examples:

• Wrong: She studied all week, she still felt nervous. Right: She studied all week, but she still felt nervous.
• Wrong: The engine is old, it needs replacing. Right: The engine is old; it needs replacing.

Error hunt

Which of these are comma splices? Fix each one, then check below.

1. The library closes early on Fridays, plan your visit accordingly.
2. After the storm passed, the streets slowly filled with people.
3. He apologised at once, his face turned red.
4. Reading widely builds vocabulary, it also sharpens your ear for style.

Answers: (1) Splice. Fix: The library closes early on Fridays, so plan your visit accordingly. (2) Not a splice. After the storm passed cannot stand alone, so the comma is correct. (3) Splice.

Fix: He apologised at once; his face turned red. (4) Splice. Fix: Reading widely builds vocabulary, and it also sharpens your ear for style.

Make it a habit

At every comma, cover it and ask: could both sides stand alone as sentences? If yes, you have a splice. If one side starts with when, because or although, the comma is fine.

Use different fixes. Too many full stops make writing short and choppy.

Too many ands make it long and loose. Mixing full stops, semicolons and dependent clauses shows range.

When you proofread, read aloud. If your voice stops but the page has only a comma, check for a splice.

Where students get stuck, and how we help

Students often splice when they write quickly and the ideas feel connected. In our First Language English lessons, a teacher marks every splice in your own writing and shows which of the four fixes suits each one.

Lessons start from RM70/hr. You can book a paid one-hour trial to see how it works.

Next step

Try more passages in the practice area and use the proofreading guide on your last essay. Then read about run-on sentences and sentence fragments. For exam day, use the last-ten-minutes checking routine.

Next, visit our original practice tasks to use the rule in your own writing. Our IGCSE English tuition page explains how lessons run. When you are ready, the paid one-hour trial is the first step.