Difference Between Assume & Presume

Instructor: David Boyles

David has a Master's in English literature. He has taught college English for 5+ years.

Is there a difference between the words 'assume' and 'presume', or do they mean the same thing? They both mean to suppose something to be true, but they differ based on how sure you are. Find out which one is which in this lesson.

How Sure Are You?

Many people think that the words 'assume' and 'presume' are synonyms, that is, they are words with the same meaning that can be used interchangeably. But is this true?

Well, yes and no. Both words are verbs, meaning they describe actions. And if you look both words up in a dictionary, you are likely to see a definition that is either identical or very similar, as both words mean to 'suppose something to be true'.

However, as we shall see a little later in the lesson, they do mean different things depending on what that supposing is based on. In addition, both words have secondary definitions that are quite different.

No matter which definition you are going for, you want to make sure you use the right word, so let's look at each of them closely.


'Assume' means to suppose something to be true based on little or no evidence. Basically, you make an assumption despite not having any solid reason to do so. Let's look at some examples to see how it works:

  • When I go to this new school, I am worried about what people are going to assume about me.
  • Jan assumed Bob wouldn't be home, but was wrong.
  • I just assumed you didn't like me because you didn't tell me any different.

In all of these sentences, the person doing the action is making an assumption based on no evidence.

In the secondary definition of 'assume', it also means to take on a job or responsibility:

  • Joan assumed the role of attorney general for the district.
  • Since no one else stepped up, Greg assumed all of the responsibility for the group project himself.


As we mentioned above, when you assume, you do it with no evidence or reasons. 'Presume' is the opposite, as it means to suppose something based on probability. Basically, you have some reason, such as evidence, to think that it is more likely to be true than not. When you 'presume', you have a stronger sense of certainty than when you merely 'assume'. Let's take a look at it in action:

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