Why is "would of" a mistake?

Would of, could of, and should of are mistakes. Have you ever found yourself writing any of these?

Of and have sound similar when we say them out loud. This is especially true when we use the contractions would've, could've, and should've. Don't get tricked! Have (or 've) is the correct choice.

Incorrect

I would of called you, but I lost your number.

I could of danced all night.

I should of ordered a salad.

Correct

I would've called you, but I lost your number.

I could've danced all night.

I should've ordered a salad.

Why is of a mistake?

Would, could, and should are helping verbs that need to be a part of something called a verb phrase. Verb phrases are made up of one or more helping verbs and a main verb. Have can function as a helping verb. Of can't.

In our incorrect sentences, would, could, and should are followed by the word of, which is hopelessly trying to be a helping verb. But no matter how hard it tries, of is limited by its definition and function. The word that people mean to use here is the verb have.

Verb Phrases

The verb phrases in our example sentences are would have called, could have danced, and should have ordered. Would, could, should, and have are helping verbs. Called, danced, and ordered are main verbs.

Verb Phrase	Helping Verbs	Main Verb
would've called	would, have	called
could've danced	could, have	danced
should've ordered	should, have	ordered

If you want to learn more about how words like of and have work, our Get Smart grammar program will teach you. Watch the short instructional videos, diagram sentences, and enjoy learning how our language works. I'll make it really easy on you! I promise.