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Comma before “based on” — All You Need to Know

Comma before “based on” — All You Need to Know

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A lot may wonder when to use commas and where to put them in a sentence. Using commas correctly can really make a big difference in communicating.

So, it is always an edge to learn more about its usage and when to use them, especially in specific daily phrases.

When it comes to using a comma before the phrase based on,” the rules can be somewhat tricky.

Let’s take it easy today as we learn more about properly using a comma before the phrase “based on.”


When is a comma needed before “based on”?

A comma is needed before “based on” when it appears before an introductory expression. “Based on” appearing in the middle or end of the sentence as a parenthetical piece of information also requires a comma. A comma should also be used when “based on” appears after a direct address.


In general, whether or not to use a comma before “based on” depends on the context and the structure of the sentence. 

In cases where “based on” is being used to indicate the reason or cause for something, it is generally preceded by a comma.

More particularly, this should happen when “based on” is used to introduce the reason as an additional piece of information.

To enrich the sentence’s meaning, rather than to make its grammar complete, a pre-comma is needed.

Here’s an example to show how that works:

“The management’s decision is final, based on the information presented at the meeting today, no matter what we say or do.”

In the sentence above, “based on the information presented at the meeting” explains why the decision was made.

This piece of information interrupts the sentence flow midsentence for the sake of adding flavor to the sentence, hence the comma.

However, if “based on” is being used to indicate the source of information or a foundation for something, it is usually not preceded by a comma.

More precisely, this happens when “based on” is used to a grammatically essential or restricted idea.

In the next example, “based on” and everything else after it serves as the sentence’s complete predicate.

For example:

“The research paper is based on data collected over the past year.”

“Based on data collected over the past year” indicates the source of the information used in the research paper.

It specifically appears after the main verb and represents the predicate part of the given sentence, hence the absence of a comma.

In essence, the two mentioned rules are what we mainly have to remember to decide whether a pre-comma should be used.

But, as writing is a lot more complicated than we normally think, there are some other nuances that we need to learn.

In the next subsections, you’ll find out how these can be done in detail.


Comma before “based on” after an introductory expression

When “based on” follows an introductory expression, a comma is generally used to separate the introductory phrase from the sentence’s main clause.

An introductory expression is a phrase or clause that comes at the beginning of a sentence and sets the stage for the following main clause.

Examples of introductory expressions include phrases such as “after considering all options,” “despite the challenges,” or “in light of the recent developments.”

For example:

Luckily enough, based on a majority vote, the proposed changes have been approved.


In the sentence above, the phrase introduced by “based on” appears after the introductory expression “luckily enough.”

From this vantage point, a comma should be used before “based on” as it is needed to separate the introduction from the rest of the sentence.


Comma before “based on” in the middle of a sentence

When “based on” is used in the middle of a sentence, it is usually set off by commas. Take note, though, that this should happen on a special case.

Having “based on” appearing midsentence with a pre-comma suggests that it is an interruptive expression.

In other words, whatever “based on” introduces does not call for grammatical restriction.

Instead, it is mainly used to enhance the meaning of the sentence rather than make it grammatically complete.

So the comma helps in telling the reader that the idea introduced by “based on” is just a piece of parenthetical information.


I think that, based on my investing experience, we shouldn’t put all our eggs in one basket.


This would also mean that this parenthetical idea can be conveniently removed without hurting the grammaticality of the remaining parts.


I think that we shouldn’t put all our eggs in one basket.


It is worth noting that if the phrase is important to the meaning of the sentence or cannot be removed without changing the meaning of the sentence, then it should not be set off by commas.

Another common circumstance that would lead to a comma used before “based on” appearing midsentence is when it is preceded by a dependent clause.

A dependent clause is also known as a subordinate clause. While using a comma before a subordinate clause is tricky, knowing how to do it right is priceless.

This sentence structure is what we normally call a “complex sentence type,” where at least one dependent and one independent clause should make it up.

When the dependent clause, the clause headed by the subordinating conjunction, begins the sentence, a comma should set it off from the succeeding part.

In this case, when “based on” happens to follow, a pre-comma should be carefully observed.


Unless you want to look older for your age, based on research, you should drink at least a liter and a half of water every day.


The sentence above shows a complex sentence structure in an inverted order, in which the dependent clause comes before the dependent clause.

Since this is the case, a comma before “based on” is needed. This is also done because the “based-on” phrase is a parenthetical idea.


Comma before “based on” at the end of a sentence

Parenthetical ideas may also come at the end of the sentence. When this happens to “based on”, a comma would be necessary too.

To know this, it is best to consider whether the preceding clause can be treated as a whole sentence or not.

If it can stand alone, then the comma would most likely be necessary. This technique also puts the idea introduced by “based on” in the spotlight.


The project is going well, based on the feedback we’ve received so far.


Again, remember that the remaining parts should still make sense even after removing the part introduced by “based on” to know that a comma should be used.


The project is going well.


Comma before “based on” after a direct address

A comma should also be placed before “based on” when it is preceded by a direct address, which can be a name directly referring to the receiver of the message.

The comma sets the direct address off from the rest of the sentence, giving the reader an idea that the message is directed toward someone.


Mary, based on everything you’ve said, there’s really no way Tom could have done the crime.


Remember that a comma before or after names used as direct references to message receivers is always a must.

Doing so clarifies the idea that the name is neither used as a subject nor object in the sentence, but rather as an addressee’s name.

In casual language use, though, most people skip the comma to make communication more convenient.


No comma before “based on” as a regular preposition

When “based on” is used as a preposition to indicate the basis or reason for something, no comma should be used before it.

Take note that this is the general rule for as long as the prepositional use of “based on” is not for parenthetical reasons.


The strategy we’re taking is mainly based on our wildest assumptions.

As you can see, “based on” is an essential part of the sentence that, without it, the sentence will never work out.

This rule applies to all other compound prepositions like “according to,” “by means of,” “because of,” and “in spite of.”

More importantly, this rule also applies to all other single-word prepositions, like “via,” “with,” and “despite.”

In case you want to know how to use a comma before “via” or a comma before “with” in more detail, feel free to check out our previous posts.


Frequently Asked Questions on “Comma Before ‘Based on’”

How can we use “based on” in a sentence?

“Based on” is used to suggest ideas that are grounded on a certain source or foundation. For example, we can say “Based on the scope of the evidence, the accusation is legally valid.”


What is a synonym for “based on”?

Synonyms for “based on” include “grounded on,” “rooted in,” and “originating from.” This phrase is used to suggest that something has a foundation or source. It works the same way as when we are citing references in academic papers.


Should it be “based on” or “based upon”?

“Based on” is the more widely-used version to date, hence the better default choice. However, “based upon” is also a grammatically valid phrase, albeit having a more formal connotation than “based on.



Commas are an important aspect of grammar, as they help to separate and clarify the different parts of a sentence.

Using commas correctly can make a big difference in making sure that your writing is clear and easy to understand.

Whether to use a comma before “based on” would always depend on the context and structure of the sentence.

So, learn and practice how to use your commas right, and never be afraid to write anything ever again.