Grammar & Usage

3 Common Comma Mistakes You’re Making (& How To Fix Them)

common comma mistakes and how to fix them

Today we’re talking common comma mistakes. In my experience, mistakes with commas make up for the majority of errors I correct when editing. (Mistakes with hyphens are a close second—but that’s an article for another day.)

Why should we care about commas? Most readers don’t know the ins and outs of comma usage more than writers. Do your readers notice the comma mistakes you’re making? Do they care?

The answers are probably not and probably not, but consider this: correct comma usage makes for a much easier reader experience, allowing your message to get across effortlessly. Commas that are all over the place can distract the reader and sabotage comprehension. That’s why it’s best to have an editor fix all your comma mistakes before you hit publish. Even better, you can learn the rules of correct comma usage to improve your own writing first.

So what are the 3 most common comma mistakes I see as an editor, and how can you fix them in your own writing?

Below you can find out more about joining commas, Oxford commas, and even—gasp!—unnecessary commas.

Common Comma Mistake #1: Not using the joining comma

When you have a sentence containing 2 independent clauses joined by a coordinating conjunction, you need to use a comma before the coordinating conjunction.

Whoa whoa whoa, back up. What’s an independent clause? And what’s a coordinating conjunction?

An independent clause is part of a sentence that contains a subject and predicate (the predicate is the part that contains the verb—what the subject is doing).

A sentence can have more than 1 independent clause. In this case, the independent clauses are joined by a coordinating conjunction—some common ones are and, or, and but.

Let’s look at an example:

Wrong: Michael Scott is Regional Manager of the Scranton branch and his assistant is Dwight Schrute.

Right: Michael Scott is Regional Manager of the Scranton branch, and his assistant is Dwight Schrute.

The first independent clause here is Michael Scott is Regional Manager of the Scranton branch. The second independent clause is his assistant is Dwight Schrute. These clauses are joined by the coordinating conjunction and. All you need to do is remember to put a comma before the coordinating conjunction. Simple!

Looking for more on joining commas? The University of Sussex has a great webpage with a short but thorough explanation.

Common Comma Mistake #2: Inconsistent use of the Oxford comma

The use of the Oxford comma, also known as the serial or listing comma, is another common mistake I see writers make.

I can hear you shouting at your computer now: But the Oxford comma is optional!

Right: Kevin, Oscar, and Angela work in Accounting at Dunder Mifflin.

Right: Kevin, Oscar and Angela work in Accounting at Dunder Mifflin.

You are right about that. Using the Oxford comma is mostly a question of style. For example, the Chicago Manual of Style does employ the Oxford comma, while the AP Stylebook does not. If you are adhering to a standard style guide, check the rule.

Note: There are some instances where the Oxford comma is needed, independent of which style guide you use, to prevent ambiguity in your sentence, but I won’t get into that here.

The real mistake I see writers make is inconsistency with their use of the Oxford comma. If you are not adhering to any standard style guide, more power to you. But you do need to decide on your own style, then. And you need to decide whether to use the Oxford comma all the time or never, because as an editor, when I see the Oxford comma used about fifty percent of the time in your writing, I don’t know whether to correct the half of the sentences lacking the Oxford comma, or to take out the Oxford comma from the other half of the sentences.

Common Comma Mistake #3: Using commas where they’re not needed

I’ve seen a lot of text written as though it’s spoken. What I mean by that is the writer used commas everywhere they would have paused when reading their text out loud.

Don’t fall into that trap! A comma is not the written substitute for a spoken pause.

Here’s an example:

Wrong: Pam broke off her engagement to Roy, because she was in love with Jim.

Right: Pam broke off her engagement to Roy because she was in love with Jim.

You don’t need the comma before because. The clause that begins with because is a prepositional phrase, and it does not need a comma to precede it.

(This is different from the joining comma, which is used for 2 independent clauses joined by a coordinating conjunction—not a preposition.)

There are more instances where I find unnecessary commas. Consider the following:

Wrong: Toby sat Kelly down, and talked to her.

Right: Toby sat Kelly down and talked to her.

Just because you see and doesn’t mean you need a comma before it. This is not a case with 2 independent clauses (and talked to her is not an independent clause according to the rules we discussed above because it doesn’t have its own subject—the subject is still Toby). It looks like the comma should be there for emphasis when you read the sentence out loud, but its use is actually incorrect.

Usually I find unnecessary commas sprinkled throughout a text as though they exist to insist on a certain point. There are some cases when you can use a comma or a set of commas for emphasis, but this practice is less and less common. Using too many commas for emphasis can result in a strange halting reading.

Do you comma here often?

Now you know about 3 common comma mistakes and how to fix them in your own writing. If my article helped you, please drop a comment below!

I’ve insisted to my clients that comma rules are complex, and quite frankly, maddening. I certainly understand why writers make the above mistakes all the time. That’s what pro editors are for!

If you need help perfecting your comma usage, send me a 1000-word sample of your writing, and I’ll send you my annotations for free! Click here to get in touch.

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