Which Is Correct: Swam or Swum?

If you went to the neighborhood pool yesterday and today you’re telling your friend about it, would you say, “I swam” or “I swum”?

Swim is an irregular verb; if it were regular, the past tense would simply be swimmed. But that would be too easy, and English grammar rules are anything but easy. To make things worse, there’s not just one right answer to the swam vs. swum rule. It all has to do with past tense vs. past participles. Luckily, even though the rule is kind of complicated, there’s a pretty simple way to make sure you’re using the right word!

The Rule

Officially, the past tense of swim is swam, and the past participle of swim is swum.

Here are a couple of examples:

Leslie swam in the state championship meet yesterday.

I have swum at that pool before, but I don’t go there regularly.

But what’s all this about tense and participles?

What’s the Difference Between Past Tense and Past Participle?

A past participle goes with the “perfect” tense of a verb. The perfect tense is used when an action has been completed, and it looks like this: “have (or had or will have) + [past participle of the verb].”

I have swum at the YMCA for about 3 years.

That’s an example of the present perfect, which means that the action started in the past and is now ongoing.

The past perfect means an action both started and ended in the past: it was completed before you spoke about it. This form always uses had plus the past participle.

Jordan and Elissa had swum 6 laps each by the time Rob arrived at the pool.

The future perfect is used when an action is going to be completed at a certain time in the future. It uses will have plus the past participle.

When she finishes the race, she will have swum 2 miles.

So whether you’re using present, past, or future perfect tense, you need have (or had or will have) plus swum. Use the perfect tense if you’re trying to focus on the completion of the action.

If the emphasis isn’t on the action being completed, and you’re just using the simple past tense (AKA there is no have, had, or will have coming before the verb), use swam.

My cousin swum for the University of Texas when he was in college.

There’s no have, had, or will have before the verb, so we actually need swam.

My cousin swam for the University of Texas when he was in college.

Here are a couple more examples:

Josie swam yesterday, and she might go back to the pool today.

After we swam, we went out for lunch.

The Trick

As you might have already guessed, the trick is to simply look for have, had, or will have before the verb. If it’s there, you need swum! If not, use swam.

Leslie had swam in the state championship meet yesterday.

There’s had before the verb—that makes it past perfect tense, so we need the past participle swum!

Leslie had swum in the state championship meet yesterday.

You swum in the lake yesterday, didn’t you?

There’s no have, had, or will have, so we actually need swam!

You swam in the lake yesterday, didn’t you?

The crew, being shipwrecked, had swum to the island.

There’s had, so swum is correct.

“Swimmed” Is Not an Option

If English grammar rules were simple and made sense, swimmed would be the correct choice. However, we are at the mercy of many strange rules and all kinds of irregular verbs, so swimmed is actually never correct.

Drop any questions you have about swam and swum in the comments, and I’ll do my best to find you an answer!

Click here to learn about further vs. farther!

Sources:

• “SWAM or Swum: Which Is Correct?” Merriam-Webster. Accessed June 26, 2025. https://www.merriam-webster.com/grammar/usage-of-swum-vs-swam#:~:text=Which%20is%20the%20correct%20past%20participle%3F&text=Swim%20is%20an%20irregular%20verb,in%20its%20crystal%2Dblue%20water.
• Ellis, Matt. “What Is a Participle? Definition and Examples.” Grammarly, April 17, 2025. https://www.grammarly.com/blog/grammar/participle/.