How Am I Supposed to Use “Suppose?”

Both “supposed to” and “supposed” have proper usages; however, “suppose to” is an incorrect form of “supposed to.”

  • Supposed to” indicates an expectation of responsibility.
  • “Suppose” conveys an assumption. 

Many people make mistakes when using forms of the verb “suppose,” especially when speaking. Nonetheless, there is a right and a wrong way to use the word, depending on a given situation.

In most situations, the appropriate version includes an added -d, but there is one situation where the base form of the verb is the right choice. 

Let’s look at the different ways the word can function and which spelling is proper. 

Supposed to

The most common form of “suppose” comes with the addition of “to” for indicating an expectation or requirement. This form suffers the most errors in usage as many people express the sentiment as “suppose to.” That form is incorrect in this context. 

Instead, add the +d and express the idea that there is a future or ongoing responsibility. Whether the intended person upholds that commitment is questionable, but the representation of the phrase remains the same. 

Note that while people often group “supposed to” as a phrase, what is happening is that “supposed” is paired with an infinitive. An infinitive is the base form of a verb, which in English is “to (verb).” For example: to run, to sleep, to eat.

As “supposed” in this situation is a responsibility, the infinitive finishes the thought by including which action the subject is responsible for completing. 

  • Indigo is supposed to finish his homework after supper. 

A traditional school responsibility, Indigo is no exception to the expectations of the educational system. While this is an expected duty, there is no indication whether or not he will complete the homework, just that this is an expectation. Any manner of laziness or catastrophic procrastination could lead to failure. 

Note that the responsibility here is “to finish” – this is the infinitive paired with “supposed” to create the common expression “supposed to.”

  • I heard the city is supposed to repair that old road down by the mill. 

Here we have a hypothetical intention to complete a specific task. Perhaps the city will fix the road, perhaps not – this could be a rumor circulating out of sheer desperation to avoid potholes while driving on that side of town. 

Infinitive: to repair

  • Altima was supposed to bring groceries when she arrived. 

Uh oh. In the past tense, the meaning has changed. The implication here is that bringing the groceries was her responsibility, but she did not follow through. 

Notice that the infinitive verb that completes the expression is “to bring.”

To Suppose

Remember, an infinitive is to + the base form of a verb. The infinitive “to suppose” relates to an assumption or expectation without firm evidence to back it up. When you suppose something, you are more or less making an educated guess based on whatever evidence is at hand.  

As an infinitive, the verb itself will change depending on the subject of the verb:

I suppose
You suppose
He/She/It supposes
They suppose
We suppose

While this meaning usually takes the form “suppose,” if the subject is third person, there will be an additional -s. 

In addition, it can be confusing when using the past tense because the word takes the form “supposed,” which makes it resemble our earlier expression “supposed to.” Despite that, remember that this meaning has to do with making a guess rather 

  • suppose we should get some sleep since we have to be up early.  

The assumption here is that if they don’t go to sleep, they will be tired in the morning. 

  • Jimmy supposed that Sylvia did not like him as much as he thought since she ghosted him for dinner. 

Poor Jimmy. His best guess is that Sylvia does not like him, but we cannot be sure she didn’t experience an emergency that prevented her from joining him. Notice that because “Jimmy” is a third-person noun, “suppose” includes the +d that comes with conjugation. 

  • Brian supposed it would rain on the 4th of July since it does nearly every year.   

Brian is being a bit pessimistic, but at least he is basing his assumption upon data from the past. Nonetheless, he has an expectation rather than using “supposed” to indicate any responsibility. 


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