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Comma before “until”: The Complete Guide

Comma before “until”: The Complete Guide

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 The purpose of commas is to make writing clearer by splitting the words and phrases that make up a sentence apart.

Despite this fairly simple purpose, comma usage can often be confusing to new and veteran writers alike.

There seem to be too many possible rules, and sometimes the rule will change depending on whom you ask.

One common question is whether or not a comma is necessary when you are using the word “until” in a sentence.


Do you need a comma before “until”?

The word “until” can only be used to set apart a subordinate clause from the main clause of a sentence. Subordinate clauses do not typically require a comma in front of them, and when they start with “until” they almost never do. In fact, the only time you will need a comma before “until” is if you have a series of prepositional phrases, each of which starts with the word.


Until & Subordinate clauses

Sentences are split into pieces called clauses.

Put simply, a clause is any part of a sentence that contains a verb or action word. Most clauses also have a subject like “I” and an object, but these are not required.

For example, in the sentence “I ate chicken until I felt sick,” there are two clauses: “I ate chicken,” and “I felt sick.” These clauses are joined by the word “until” to show the duration of the verb in the first clause.

When you see the word “until” used in this way, the clause that follows it is called a “subordinate clause” and the clause that precedes it is the “main clause.”

The subordinate clause can also appear first in the sentence, with the main clause following, but the meaning is the same in both cases.

In other words, when “until” is used as part of a subordinate clause it connects additional information to the main idea in the sentence.


Do you need a comma before “until” at the start of a subordinate clause?

With subordinate clauses, the only time you will ever need a comma is if the clause appears at the beginning of a sentence. In this case, the comma comes after the clause.

If your subordinate clause appears at the end of a sentence, you do not place a comma before it.

Because you can never start a sentence with a comma, this means that no matter where in the sentence your subordinate clause that starts with “until” goes, you do not need to place a comma before it.



“I ate chicken until I felt sick.”

“Until last Thursday, my brother had never seen a camel.”


In the example sentences, “until” is in front of a subordinate clause. In the first sentence, because the clause comes after the main clause it does not require a comma.

In the second, the subordinate clause is at the beginning of the sentence and must be separated from the main clause by a comma at the end of the clause.

However, as noted in the section above, you never need a comma in front of this type of clause. In short, if the sentence you are using has “until” as part of a subordinate clause, you do not need a comma before “until.”


Do you ever need to use a comma before “until”?

Based on the rest of this article, it might seem like there is just never a single time you need to place a comma in front of the word “until.” Although it’s uncommon, there is one time when you do.

Any time you have a series of subordinate clauses you will need a comma in front of most of the items in the series. If each clause in the series begins with the word “until,” this is the one time you might need a comma before “until.”



“I’ll love you until the sky touches the sea, until the moon touches the sun and until the birds turn into bread.”


This sentence is very poetic, and it probably isn’t something you would write in an essay. Additionally, the reason this sentence needs the comma has nothing to do with the word “until” specifically.

Any time you find yourself writing a sentence with a series or list contained within it, you should be sure to separate the items in that series with commas.

All the same, it does serve as an example of the one time you might need to place a comma before “until.”

Depending on the style guide you use, you might also have to place a comma after “sun” in the example sentence.

Since most style guides do not add a comma before the third item in a list unless the meaning would be unclear, though, you can normally leave that final comma out.


A note on prepositions and conjunctions

Although the type of clause it appears in is a subordinate clause, the word “until” is either a preposition or a conjunction.

Both of these words are ones which show a relationship between parts of your sentence, with the only difference being that a preposition appears before a noun or noun phrase while a conjunction appears before a verb or verb phrase.

When using the word “until,” one way to tell them apart is that a prepositional phrase will usually contain a time reference and a phrase after a conjunction will not.



“I stayed up reading until midnight.”

“I just couldn’t go to sleep until I finished my book.”


In the first sentence, “until” is followed by a noun, which means it is being used as a preposition.

In the second example, the word is followed by a subordinate clause containing the verb “finished.”

Although these two uses are subtly different, they both show how long the action in the main clause takes.

Additionally, regardless of whether “until” is modifying a noun or a verb, the rules for comma usage stay the same.

That means all you really need to remember is that you almost never need a comma before “until.”


Comma before until FAQ


Does “until” the preposition need a comma before it?

As you might have guessed from the above examples, the answer is no. When you use “until” as a preposition, especially after your main clause, you don’t need to use a comma before it.


The road is clear until the dead-end ahead.


Does “until” the conjunction need a comma?

Since “until” is a subordinating conjunction, it does not need a comma so long as it comes after the main clause. In fact, it’s the same with almost all subordinating conjunctions. They don’t take a comma before them if they appear in the sentence after the main clause.


I was unsure of my decision until I spoke to the doctor.

The telemarketers kept calling me until I decided to change my number.