A compound sentence joins two independent clauses with a coordinating conjunction like and or but. A complex sentence pairs one independent clause with a dependent clause that starts with a word like because or when.
The connecting word is the key to telling them apart. Check it, and you can label either type in seconds.
What Is a Compound Sentence?
A compound sentence has two or more independent clauses. Each clause has a subject and a verb, and each can stand alone.
Two Independent Clauses Joined by FANBOYS
Seven coordinating conjunctions link the clauses: for, and, nor, but, or, yet, so. The acronym FANBOYS helps you remember them.
Both clauses carry equal weight. Neither one depends on the other.
Punctuation: Comma, Semicolon, or Conjunctive Adverb
You can join the clauses in three correct ways:
- Comma plus FANBOYS: He arrived early, but she wasn’t ready.
- Semicolon alone: He arrived early; she wasn’t ready.
- Semicolon plus conjunctive adverb and comma: He arrived early; however, she wasn’t ready.
A comma alone creates a comma splice, which is a run-on error.
Compound Sentence Examples
- The clown frightened the girl, and she ran off screaming.
- I wanted pizza, but the shop was closed.
- You can walk to class, or you can take the bus.
- It rained all day; the game went on anyway.
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What Is a Complex Sentence?
A complex sentence has one independent clause and at least one dependent clause. The dependent clause cannot stand alone, even though it has a subject and a verb.
One Main Clause Plus a Dependent Clause
A subordinating conjunction starts the dependent clause. Common ones include because, although, when, while, after, if, and since.
Take My mom smiled when I made dinner. The main clause is My mom smiled. The dependent clause is when I made dinner. It adds extra detail about the main action.
Where the Comma Goes
Put a comma after the dependent clause when it comes first. Skip the comma when it comes second.
| Order | Example |
|---|---|
| Dependent clause first | While I checked my phone, she proofread the project. |
| Main clause first | She proofread the project while I checked my phone. |
Complex Sentence Examples
- Although it was cold, we walked to the park.
- She passed the test because she studied every night.
- If you finish early, you can leave.
- The student who sits near the window won the prize.
Compound vs Complex Sentences
The two types differ in how the clauses relate. In a compound sentence, the clauses are equal. In a complex sentence, one clause is the main clause and the other depends on it.
Equal Clauses vs One Main Clause
Look at this pair:
- Compound: I washed my hands, and I ate breakfast.
- Complex: I washed my hands before I ate breakfast.
One word changed. And links two equals. Before demotes the second clause.
Coordinating vs Subordinating Conjunctions
If the connector is one of the seven FANBOYS words, the sentence is compound. If it is any other conjunction, the sentence is complex.
Learning FANBOYS is easier than memorizing the long list of subordinating conjunctions.
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Side-by-Side Comparison Table
| Feature | Compound Sentence | Complex Sentence |
|---|---|---|
| Clauses | 2 or more independent | 1 independent + 1 or more dependent |
| Clause weight | Equal | Unequal |
| Connectors | FANBOYS, semicolon | Because, although, when, if, while |
| Comma rule | Comma before the conjunction | Comma only if the dependent clause comes first |
| Example | She cooked, and he cleaned. | She cooked while he cleaned. |
How to Tell Compound and Complex Sentences Apart
A Quick 3-Step Test
- Find the clauses. Look for each subject and verb.
- Ask if each clause can stand alone as a sentence.
- Check the connector. FANBOYS means compound. Another conjunction means complex.
Can You Combine Both? Complex-Compound Sentences
Yes. A complex-compound sentence has at least two independent clauses and at least one dependent clause.
What a Complex-Compound Sentence Looks Like
Because the roads were icy, we stayed home, and we watched movies. The first part is dependent. The other two are independent.
Mixing Sentence Types for Better Rhythm
Short sentences hit fast. Longer ones add detail and flow.
Mixing simple sentences, compound sentences, and complex sentences keeps writing lively and easy to read.
FAQ‘s About Compound and Complex Sentences
What is the main difference between a compound and a complex sentence?
A compound sentence joins equal independent clauses. A complex sentence has one independent clause and one dependent clause.
How do you identify a compound sentence quickly?
Look for a comma plus a FANBOYS word between two complete thoughts. A semicolon also works.
Can a sentence be both compound and complex?
Yes. It is called a complex-compound sentence. It has two or more independent clauses and at least one dependent clause.
Do you always put a comma before a subordinating conjunction?
No. Use a comma only when the dependent clause comes first in the sentence.
Is “because” a coordinating or subordinating conjunction?
It is subordinating. It starts a dependent clause, so the sentence is complex.
Does a compound sentence need a comma?
Yes, when a FANBOYS word joins the clauses. Short clauses sometimes skip it, though the comma is safer.
Are compound and complex sentences punctuated differently in British English?
The core rules are the same. Some British writers skip the comma before and more often.
Conclusion
The difference between compound and complex sentences comes down to the connector. FANBOYS joins equal clauses, while words like because and although make one clause depend on another.
Hi, I’m John Henry, the voice behind Grammar Nudge. I make grammar simple and easy to understand, from basic rules to advanced writing tips. Clear explanations. Practical examples. No confusion.
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