Complex vs Compound Sentences

What Is a Compound Sentence?
What Is a Complex Sentence?
What Is a Compound-Complex Sentence?
Conclusion on Complex vs Compound Sentences

Using different structures improves the flow and pacing of your writing while keeping your readers engaged.

Two important sentence structures to know are complex sentences and compound sentences. So, what exactly is the difference between the two?

Read on to learn more about how to tell compound and complex sentences apart and how to use them in your writing effectively.

What Is a Compound Sentence?

A compound sentence includes multiple independent clauses that express equally significant ideas.

An independent clause is any clause that can be considered a complete sentence by itself. It needs to fulfill three criteria:

Has a subject
Has a verb
Expresses a self-contained thought

For example, “I read a book” is an independent clause because it fulfills all three of the above criteria.

You can create a compound sentence by connecting multiple independent clauses with a conjunction, such as “and,” “or,” “but,” or “yet.”

Here are some compound sentences you could make with different conjunctions:

I read a book, and my father went to the store.
Susan has brown hair, but her sister has red hair.
We can go for a walk, or we can stay at home.

You can also connect your independent clauses with a semicolon instead of a conjunction. For example, you could write:

I read a book; my father went to the store.

When you’re constructing compound sentences, be careful to avoid comma splices, which is a common grammar mistake that occurs when you connect two independent clauses with only a comma. Instead, always use a conjunction with a comma, or use a semicolon instead of a comma.

You can use a grammar checker like ProWritingAid to look for instances of comma splices in your writing. ProWritingAid can help you make sure you’re using the right punctuation for your compound sentences.

Compound Sentence Examples

Let’s look at a few examples of compound sentences.

I want cereal for breakfast, but there’s no milk in the fridge.
She finished her homework, so now she can watch TV.
He likes to run in the morning, and he also enjoys lifting weights.
Sue can be rude at times, but she’s a nice girl most of the time.
She was tired, so she went to bed early.
He studied hard for the test, yet he failed to get a passing grade.
We can go swimming at the pool, or we can go swimming in the ocean.
She sings beautifully; she also plays the guitar.
Gregg will travel by bus; he sold his car.
The baby is tired, yet it refuses to fall asleep.

What Is a Complex Sentence?

Unlike compound sentences, which contain multiple independent clauses, complex sentences include only one independent clause, along with at least one dependent clause.

A dependent clause is any clause that can’t stand alone as a complete sentence. It either lacks a subject, lacks a verb, or fails to express a full thought.

For example, “while you were sleeping” is a dependent clause because it doesn’t express a standalone thought.

You can create a complex sentence by connecting a dependent clause to an independent sentence. You can connect them using a subordinating conjunction, such as “because,” “while,” “although,” “if,” “after,” “until,” “which” or “when.”

Only include a comma between the two clauses if the independent clause comes after the dependent clause. If the independent clause comes first, don’t include a comma.

For example:

While you were sleeping, I went to the store.
I went to the store while you were sleeping.

In this sentence, “I went to the store” is the independent clause, and “while you were sleeping” is the dependent clause. The subordinating conjunction “while” connects the two clauses.

Complex Sentence Examples

Let’s look at some other complex sentence examples.

He stayed up late to finish the project although he was tired.
I will feed the cat and start dinner when I get home.
If you finish your homework, you can watch TV.
We will have a picnic outside unless it starts raining.
Since he was feeling sick, he stayed home from work.
After I finish my work, I will take a break.
As long as you study hard, you will do well on the test.
The phone rang while I was studying.
Although she had a lot of work to do, she took a break to go for a walk.
If you need help with your homework, you can ask your teacher for assistance.

What Is a Compound-Complex Sentence?

The last type of sentence is the compound-complex sentence, which includes the components of both of the sentences we’ve discussed so far.

Every compound-complex sentence needs to include the following criteria:

Multiple independent clauses, joined by a semicolon or a coordinating conjunction (which makes it compound sentence)
At least one dependent clause, joined to the rest of the sentence by a subordinate conjunction (which makes it a complex sentence)

Let’s look at an example of this in practice:

While I was cooking, the phone rang, and it was my boss.

In the example above, there are two independent clauses (“the phone rang” and “it was my boss”) and one dependent clause (“While I was cooking”).

Compound-complex sentences can be useful for adding complexity and nuance to your writing. Because they contain so many clauses, they can help you convey multiple ideas or perspectives in a single sentence.

Compound-Complex Sentence Examples

Now, let’s look at a few compound-complex sentence examples.

Although I was tired, I stayed up late to finish my homework, and I was able to turn it in on time.
When I get home, I will feed the cat and start dinner unless you want to go out to eat.
If you finish your homework, you can watch TV, but only for an hour.
Unless it starts raining, we will have the picnic outside, but we need to bring umbrellas just in case.
Since he was feeling sick, he stayed home from work, but he still managed to complete all his tasks remotely.
After I finish my work, I will take a break, and then I will start dinner.
As long as you study hard, you will do well on the test, but you need to review all the material.
Although she had a lot of work to do, she took a break to go for a walk, and she returned feeling refreshed and ready to tackle her tasks.
If you need help with your homework, you can ask your teacher for assistance, or you can work with a tutor or study group.

Conclusion on Complex vs Compound Sentences

There you have it—a complete guide to complex vs compound sentences! Here’s a quick recap:

A compound sentence includes multiple independent clauses, which are connected by a coordinating conjunction or a semicolon
A complex sentence includes at least one dependent clause, which is connected to the rest of the sentence by a subordinating conjunction
Finally, a compound-complex sentence includes two or more independent clauses, as well as at least one dependent clause

Now you’ve learned about compound and complex sentences, you can include them in your own writing.

Don’t forget to use different sentence structures so your writing doesn’t appear boring and monotonous. If you need guidance on where to start, use ProWritingAid’s sentence structure report to show you where your sentences could use a little more attention.

Complex vs Compound Sentences

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