# Comma splice
A comma splice is a punctuation error in which a single comma joins two independent clauses, that is, two groups of words each of which could stand alone as a complete sentence, without a coordinating conjunction or other appropriate joining word between them.[1](https://advice.writing.utoronto.ca/revising/comma-splices/) The classic example is "I completed my essay, I have not submitted it."[1](https://advice.writing.utoronto.ca/revising/comma-splices/) The comma is not strong enough to make one grammatical sentence out of two.[1](https://advice.writing.utoronto.ca/revising/comma-splices/)
| Key fact | Detail |
|---|---|
| Definition | Two or more independent clauses joined with only a comma[2](https://writingcenter.tamu.edu/guides/resources/common-errors.html) |
| Related error | The run-on (fused) sentence joins independent clauses with no punctuation at all; the two errors are fixed by the same methods[1](https://advice.writing.utoronto.ca/revising/comma-splices/) • [3](https://www.fordham.edu/academics/academic-resources/writing-center/writing-resources/grammar/run-ons/) |
| Standard fixes | A period, a semicolon, a comma plus a coordinating conjunction, or subordination of one clause[1](https://advice.writing.utoronto.ca/revising/comma-splices/) |
| Coordinating conjunctions | Seven: and, but, or, nor, for, so, yet[1](https://advice.writing.utoronto.ca/revising/comma-splices/) |
| Common false fix | A comma followed by a conjunctive adverb such as however still produces a comma splice[1](https://advice.writing.utoronto.ca/revising/comma-splices/) |
| Accepted uses | Idiomatic constructions, series of three or more clauses, and fiction dialogue or first-person narration[4](https://style.mla.org/splices/) |
| Detection | Grammar-checkers do not always catch comma splices[5](https://www.hamilton.edu/academics/centers/writing/style/essentials/comma-splice) |
## Definition and related errors
The grammatical term for a group of words that can stand on its own as a complete sentence is an independent clause; it must contain both a subject and a verb.[1](https://advice.writing.utoronto.ca/revising/comma-splices/) A comma splice occurs when two or more such clauses are joined with only a comma.[2](https://writingcenter.tamu.edu/guides/resources/common-errors.html) The closely related run-on sentence, also called a fused sentence, joins two complete sentences without any punctuation mark at all, as in "I completed my essay I have not submitted it."[1](https://advice.writing.utoronto.ca/revising/comma-splices/) Some writing centers treat both kinds as run-ons, with the comma splice as one of two forms.[3](https://www.fordham.edu/academics/academic-resources/writing-center/writing-resources/grammar/run-ons/)
Sentence length is not the test. How long a run-on is makes no difference to its status, so run-ons may be quite brief while sentences of great length can still be perfectly grammatical.[6](https://writingcenter.post.edu/articles/grammar-the-sentence/)
## How to fix a comma splice
Writing centers describe four standard remedies, and advise varying them rather than always solving the problem the same way.[1](https://advice.writing.utoronto.ca/revising/comma-splices/)
1. **Use a period.** Replace the comma with a period, making two sentences. This works well when the logical connection is self-evident, one or both clauses are long, or the ideas are distinct.[1](https://advice.writing.utoronto.ca/revising/comma-splices/)
2. **Use a semicolon.** This keeps the two ideas in one sentence and suits clauses whose connection is already clear and closely related, especially relations of sequence in time or logic.[1](https://advice.writing.utoronto.ca/revising/comma-splices/) A semicolon may be followed by a transition such as however or therefore.[2](https://writingcenter.tamu.edu/guides/resources/common-errors.html)
3. **Add a coordinating conjunction after the comma.** The seven coordinating conjunctions are and, but, or, nor, for, so, and yet; they cover the most basic logical relationships between two ideas, so this fix also states the relationship, as in "I completed my essay, but I have not submitted it."[1](https://advice.writing.utoronto.ca/revising/comma-splices/)
4. **Use a subordinating conjunction.** Words such as although, because, since, if, when, and while make one clause dependent, laying unequal stress on the two parts; placing although at the start makes the subordinated clause the point, while placing it second makes it an afterthought.[1](https://advice.writing.utoronto.ca/revising/comma-splices/)
**A common false fix.** Joining two sentences with a comma followed by a conjunctive adverb, most often however, is still a comma splice: "I completed my essay, however I have not submitted it" remains an error. Conjunctive adverbs such as however, nevertheless, therefore, and moreover should begin independent clauses, not join them; to use one in a fix, put a period or semicolon in front of the second clause.[1](https://advice.writing.utoronto.ca/revising/comma-splices/) The MLA Style Center adds a dash as an acceptable substitute for the comma.[4](https://style.mla.org/splices/)
## When a comma splice is accepted
Style authorities treat the rule as a default rather than an absolute. The MLA Style Center notes that commas are acceptable in idiomatic constructions when the second part completes the sense of the first, and in a series of three or more items, giving "It's not just the customers who are exasperated, it's the employees too" and "We came, we saw, we conquered."[4](https://style.mla.org/splices/) [Comma](https://www.edgepedia.org/comma) splices are also acceptable in fiction: in dialogue and first-person narration a character might be excited or upset and speak in a rush, and the minimal pause conveyed by a comma can clarify sentence structure while conveying the character's state of mind.[4](https://style.mla.org/splices/)
[The Chicago Manual of Style](https://www.edgepedia.org/the-chicago-manual-of-style)'s Q&A records that some editors argue a comma splice is not truly an error but two independent clauses joined by an elided conjunction, as in "Paul put the kettle on, [and] Don fetched the teapot"; such elision is more common in casual prose and has its place in creative writing. With a series of three or more independent clauses, convention retains only the final and.[7](https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Commas/faq0094.html)
The Australian Style Manual states the rule plainly for public writing: do not use a comma to link two stand-alone sentences unless a coordinating conjunction is used.[8](https://www.stylemanual.gov.au/grammar-punctuation-and-conventions/punctuation/commas)
## Detection and correction by machine
Grammar-checkers do not always catch comma splices.[5](https://www.hamilton.edu/academics/centers/writing/style/essentials/comma-splice) Research has addressed the gap: a 2018 study introduced two machine-learning models to correct run-on sentences, reporting that they outperformed leading methods for the related tasks of punctuation restoration and whole-sentence grammatical error correction.[9](https://arxiv.org/abs/1809.08298)
## References
1. [Fixing Comma Splices, Jerry Plotnick, University College Writing Centre, University of Toronto](https://advice.writing.utoronto.ca/revising/comma-splices/)
2. [Common Grammar Errors, University Writing Center, Texas A&M University](https://writingcenter.tamu.edu/guides/resources/common-errors.html)
3. [Run-ons, Fordham University Writing Center](https://www.fordham.edu/academics/academic-resources/writing-center/writing-resources/grammar/run-ons/)
4. [To Splice or Not to Splice?, Angela Gibson, MLA Style Center](https://style.mla.org/splices/)
5. [Comma Splice, Nesbitt-Johnston Writing Center, Hamilton College](https://www.hamilton.edu/academics/centers/writing/style/essentials/comma-splice)
6. [Grammar (The Sentence), Post University Writing Center](https://writingcenter.post.edu/articles/grammar-the-sentence/)
7. [Commas Q&A, The Chicago Manual of Style Online](https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Commas/faq0094.html)
8. [Commas, Australian Government Style Manual](https://www.stylemanual.gov.au/grammar-punctuation-and-conventions/punctuation/commas)
9. [How do you correct run-on sentences: it's not as easy as it seems, arXiv:1809.08298](https://arxiv.org/abs/1809.08298)
---
*Topic: Encyclopedia › Society and history › Languages and linguistics › Linguistics › Grammars and phonologies of individual languages › English grammar and phonology*
*Initially written Sep 17, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license