What’s the difference between based off and based on?

Key takeaways:

Based on is the correct and formal phrase, used to describe something derived from a source or reference.
Based off is often used informally, primarily in spoken American English, but is generally considered incorrect in formal writing.
Use based on in most contexts, especially in professional, academic, or formal writing.
Based off tends to be used in informal speech but avoided in written communication.

Part of the series “Grammar Debugged—English for Devs”

Language is full of subtle nuances, and understanding the differences between similar phrases can help you communicate more clearly and accurately. One common source of confusion is the difference between based on and based off. Though they are often used interchangeably, one is more appropriate than the other in different contexts. In this Answer, we’ll explore the distinction between these two phrases, when to use each one, and highlight common mistakes people make.

What is based on?

Based on is used to indicate that something is founded on or grounded in a particular idea, source, or concept. It is more formal and is used to refer to facts, theories, or sources of information that something is directly built upon.

Examples

The movie is based on a true story.
Her research is based on years of data analysis.
The design was based on modern architectural principles.

Key Point: Use “based on” when referring to sources, foundations, or inspiration for something.

Use “based on” when referring to something that is grounded in a specific reference, fact, or idea.

What is based off?

Based off (often written as based off of) is an informal variation, most commonly heard in spoken American English. It is considered less formal and is generally used when trying to imply that something is derived from something else. However, in professional writing, based off is often viewed as incorrect.

Examples

The movie was based off of a popular comic book.
The game was based off a true story.
His idea was based off our previous discussion.

Use “based off” in informal, conversational contexts (primarily in spoken American English), but avoid it in formal writing.

Common mistakes when using based on and based off

Mistake 1: Using based off in formal writing
- Incorrect: The novel is based off a real event.
- Correct: The novel is based on a real event.
Mistake 2: Mixing based on and based off in the same sentence
- Incorrect: The design is based on inspiration based off nature.
- Correct: The design is based on inspiration from nature.

Frequently asked questions

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What does off-based mean?

Off-based isn’t a standard phrase. You might mean based off, which is informal and often incorrect in formal contexts.

Which is correct, based from or based on?

Based on is correct. Based from is not grammatically standard.

What is another word for based off?

Alternatives words for based off includes derived from, inspired by, or adapted from (though based on is preferred).

Is “off of” grammatically correct?

Off of is informal and often seen in spoken language but should be avoided in formal writing. Off alone is preferred.

Why do Americans say based off instead of based on?

Based off has become colloquial in American English due to regional variations and natural language evolution. It’s more casual but not technically correct in formal contexts.

Key aspect	*Based on*	*Based off*
Definition	Derived from, grounded in, or influenced by a source	Derived from or loosely based on something (informal)
Usage	Formal, standard usage in writing and speech.	Informal, often used in spoken American English.
Contexts	Professional, academic, formal writing, and speech.	Casual conversations, informal speech.
Example	The documentary is based on historical facts.	The movie is based off a popular book series.