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Comma Before “Unless”: Rules, Usage & Examples

Comma Before “Unless”: Rules, Usage & Examples

Commas have a bad reputation, especially among less confident writers. The rules of when and how to use them seem arbitrary, and that makes anything scary.

The reasons for this vary. Some people may have never learned proper usage, or were taught using old-fashioned style guides that made the rules less clear rather than explaining them.

It’s also worth noting that some style guides require you to use commas in slightly different places, so your answer might differ depending on the style guide you are using for a project.

Style guides aside, though, there are some rules about commas that never change. Let’s take a look at one example.



Do You Need to Put a Comma Before ‘Unless’?

The key to understanding this question is to know that ‘unless’ is a conjunction. Conjunctions are words that are used to connect the clauses or parts of a sentence. In other words, we need to know if conjunctions need a comma. The only conjunctions that require a comma first are andyet, but, or, for, nor and so.

Even then, a comma is only used when the two parts of the sentence are independent of one another. This means that in most cases you absolutely do not need a comma before ‘unless.’ As we will see, though, in more complicated sentences there are times when you will still need a comma.


Comma Rules for Conjunctions like Unless

Before we look at some of the cases when you do need a comma before unless, let’s go into a little more detail about why you don’t usually need one.

As noted above, ‘unless’ is a conjunction. It stands to reason, then, that knowing how to use conjunctions in your writing will help you better understand when to use commas.

Conjunctions are words used to combine different parts of a sentence, called clauses. The best way to think of a clause is as any part of a sentence that contains a verb or action word.

There are two types of clause. Independent clauses make sense if you take them out of the sentence. Dependent clauses do not.

Let’s look at some examples of both and see when commas are needed.


Use Commas in Independent Clauses

An independent clause is basically a complete sentence, and if you take it out of the sentence it’s in it should make sense by itself.

For independent clauses, you will almost always use a comma before the conjunction.

The first sentence of this section is one example of a sentence with two independent clauses. If you cut it in half at the “and,” both parts of the sentence make sense.

The word ‘unless’ is a conjunction, but it can’t be used to make independent clauses, which means it doesn’t usually take a comma.

Here are some other examples of independent clauses.



My brother wanted to bake a cake, so he bought ingredients.

I hate flowers, and lavender makes me sneeze.



Both of the sentences above have two independent clauses.

In the first example, “My brother wanted to bake a cake.” can stand alone, and so can “He bought ingredients.”

Likewise, in example number two, both parts of the sentence are coherent without the other.

If you’re still not convinced, replace the comma and the word ‘and’ in the second sentence with a period. Both sentences still make sense, and their meaning has not changed.

As we will see shortly, this is an easy way to tell independent and dependent clauses apart. It can also help with comma placement.

If you are writing a sentence and aren’t sure whether it needs a comma, try reading both clauses as separate sentences and see if they still make sense.


Don’t Use Commas in Dependent Clauses

Unlike independent clauses, dependent clauses don’t make sense if you take them out of their original sentence.

In other words, a dependent clause depends on the full sentence to make sense. Grammatically speaking, the clause is dependent on the main clause in the sentence. However, it’s easier to just remember that if you take a dependent clause out of the sentence it is in, it becomes meaningless.

Dependent clauses almost never require commas unless there is something else in the sentence making you use one.

Because ‘unless’ can only be used at the start of a dependent clause, this means you will almost never need a comma before ‘unless.’

Here are some examples of dependent clauses.



You shouldn’t eat broccoli unless you like it.

She refused to jump out of the plane until she had a parachute.



Both of the sentences above have an independent and a dependent clause. To see how this is different from the previous examples, let’s split the first sentence into two separate sentences, minus the word ‘unless.’

You shouldn’t eat broccoli. You like it.

While both new sentences might technically make sense, the meaning of the second has changed completely. In the original example, it is clear that the person who shouldn’t eat broccoli will only eat it if he likes it.

Some people might not like broccoli, so they won’t eat it. In our new sentences, however, it sounds like the person does like broccoli.

The same is true for the second example, where the word ‘until’ clearly explains why she refused to jump out of the plane. Taking that word out of our sentence changes its meaning.

Because these sentences change their meaning when taken apart, they are examples of dependent clauses. That means they do not need a comma


Times You Might Need a Comma Before Unless

To be honest, unless you are trying very hard, there are not many reasons you will ever need to put a comma before the word ‘unless.’

However, as the previous sentence shows, the word does sometimes still require a comma. This has nothing to do with the word itself, but is a result of other grammar rules about commas.

So when do you want a comma before ‘unless’?


When Part of the Sentence Isn’t Essential

In more complicated sentences, commas are often used to set off parts that can be skipped.

Technically these are called ‘parenthetical expressions,’ and the easiest way to spot them is to read the sentence aloud without each part and see if it still makes sense.

If you can take part of the sentence out without changing the coherence of the rest of it, you should place a comma before and after it.

Alternately, if the parenthetical expression is at the end of a sentence, you simply place a comma before it.

The word ‘unless’ can sometimes start a parenthetical expression, so this is one example when you might need a comma before ‘unless.’



Most people find it reassuring to know that, unless they are unlucky, they will probably never be lit on fire.



In this example, the phrase, “unless they are unlucky” is not essential to understanding the sentence. Because of that, we set it off with commas.

Since the phrase begins with the word ‘unless,’ this is one case where you need a comma first.


When You’re Making a List

If you’re writing about a list of more than two things, you will need to use a comma to separate most items in the list.

This is one case where the rules vary depending on your style guide. Some guides require you to use a comma for all items in the list, including the last.

This is called the serial comma or Oxford comma. Other style guides take the opposite approach. For these, you don’t put a comma before the last item in a list, but you still need one for all the other items.

As a general rule of thumb, you can leave out the comma before the last item in a list unless putting one in will reduce confusion.

One famous example of this is the sentence, “I want to thank my parents, Ayn Rand and God.” Because there is no comma after Ayn Rand, it seems like she and God are the author’s parents, which is probably not correct.

If you are making a list where each item is a possible exception, this is one place where you might need a comma before ‘unless.’



He refused to serve hamburgers unless you paid double, unless your name was Alfred and unless you were very polite.



In this example, the second ‘unless’ needs a comma because it is the second item in a list. Note that in some style guides you would also need a comma before the final item in the list.

Again, though, it’s important to remember that in almost all cases you don’t need a comma before ‘unless.’ When you do, it’s usually because of other grammar rules around commas and not because of the word itself.