Key takeaways
- Use a comma before “but” when it joins two independent clauses (each could stand as its own sentence).
- Do not use a comma before “but” when it connects two elements within a single clause.
- A comma before “but” is never wrong when joining independent clauses; omitting it in that case is the error.
- Short contrasting phrases (“I tried but failed”) work without a comma, but adding one is acceptable.
- The same rule applies to all coordinating conjunctions in the FANBOYS acronym: for, and, nor, but, or, yet, so.
The comma-before-but rule is not as complicated as most style guides make it look. There is really one core test, and once you know it, almost every case resolves itself.
This guide gives you the rule, the test you can apply in seconds, a set of clear examples, and the edge cases that genuinely require a judgment call.
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The independent clause test
Before you decide whether to add a comma before “but,” ask: can both parts of the sentence stand alone as complete sentences? If yes: use a comma before “but.” If no: skip the comma.
Examples with two independent clauses (comma required)
- She studied all week, but she still felt unprepared.
- The report was finished on time, but the manager requested changes.
- I wanted to go to the concert, but the tickets had sold out.
Examples with one clause (no comma)
- She studied hard but still felt unprepared.
- The report was finished on time but required changes.
- I wanted to go but couldn’t get tickets.
Practice this rule with an English tutor online by reviewing your own writing together.
The FANBOYS rule
“But” is one of seven coordinating conjunctions: For, And, Nor, But, Or, Yet, So. You can remember them with the acronym FANBOYS. The comma rule applies to all of them equally.
| Conjunction | With comma (two clauses) | Without comma (one clause) |
|---|---|---|
| And | She called, and he answered. | She called and waited. |
| But | He tried, but it didn’t work. | He tried but failed. |
| Or | You can leave now, or you can stay for dinner. | You can leave or stay. |
| Yet | She was exhausted, yet she kept going. | She was exhausted yet determined. |
Work on FANBOYS conjunctions with an online English teacher so your punctuation becomes consistent.
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Short sentences: when the comma is optional
When both clauses are very short, the comma before “but” is often omitted. Style guides generally accept either version. The comma helps when the sentence is long enough that the reader needs a pause to track the contrast.
When “but” starts a sentence
Starting a sentence with “but” is grammatically acceptable. When “but” opens a sentence, no comma is needed immediately after it unless the following clause itself requires one.
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“But” in lists and comparisons
When “but” appears in a comparison (“smart but inexperienced”) it does not join two independent clauses and takes no comma. In “nothing but the truth,” “but” functions as a preposition meaning “except” and the comma rule does not apply. Build your punctuation confidence with an English tutor through direct review of your sentences.
Common mistakes
Comma after “but,” not before it.“She wanted to come, but, she had too much work” adds an incorrect second comma. Do not add a comma directly after “but” without a reason. Omitting the comma when two full clauses are joined.“She completed the assignment but the deadline had already passed” is missing the comma. Both halves are independent clauses; a comma before “but” is needed. Adding a comma when only phrases are joined.“He was tired, but happy” is unnecessarily punctuated. “Tired” and “happy” are adjectives modifying the same subject, not independent clauses. The independent clause test is reliable and fast. Learn faster with personal guidance from expert tutors on italki trusted by over 10 million learners.Book a trial lesson today.
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FAQ
Does the comma rule change in British English?
No. The rule is the same in British and American English: comma when joining two independent clauses, no comma when joining phrases within one clause. Can I put a comma before “but” for stylistic emphasis, even if only one clause follows? Technically this is incorrect by standard grammar rules. In creative or informal writing, writers sometimes use punctuation for rhythmic effect. For academic or formal writing, stick to the rule. What about “not only… but also”? In a “not only… but also” construction, no comma is used between the elements if they are part of the same clause: “She was not only talented but also hardworking.” When each introduces its own independent clause, a comma before “but” is correct.
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