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Time Flys or Time Flies: Which is Correct?

You’re enjoying the atmosphere and company of your friends and, suddenly, you look at your watch and realize that it’s much later than you thought! You didn’t notice that the time was passing, so, in this situation, we say that “time flies,” or is it “time flys”?

The correct spelling is “time flies,” which means that time can pass without you realizing it. This is because “time” is a noncount noun, and we’re using the verb “to fly” in the simple present tense and in the singular, third-person form. To add the necessary “s,” we must drop the -y and add -ies.

Basically, our noncount noun “time” acts as third-person “he/she/it,” so we need to add “s” in the third-person singular present tense. In this article, we’ll cover the spelling rules involved as well as the proper usage of this phrase.

Why Is “Time Flies” Correct?

If you’ve ever found yourself asking, “Is it correct to say, ‘Time flies’?” yes, it is! This is because it’s a sentence in the simple present tense, and the subject “time” is a noncount noun that acts as singular third-person “it” in this sentence. 

Because of this, we need to conjugate the verb “to fly” by adding “s” at the end. However, to do this, we have to follow the spelling exception for verbs that end with “y,” so we change the end of the verb to -ies (source). Our final result is the sentence “time flies.” 

Let’s break down some of the grammar and spelling rules that explain why it is correct to say, “Time flies.”

Verbs That End With Y

Verbs that end with the letter “y” have some special spelling exceptions, especially when we conjugate them in the simple present tense, the simple past tense (verb 2), the present participle (verb+ing), and the past participle (verb 3). Let’s see how these rules apply to each situation.

Simple Present Tense and Verbs That End With Y

When we use the simple present tense, we use the simple form of the verb, which we also call verb 1.

For subjects that are in the first or second person (such as “I,” “we,” and “you”), verb 1 doesn’t change.

For subjects that are third person and plural (i.e., “they”), verb 1 doesn’t change. However, for subjects that are in the third person and singular (such as “he,” “she,” “it”), we add an “s” to the end of verb 1 (source).

This is an easy rule, but verbs ending with “y” have a special exception about the spelling of the verb. 

Basically, if the verb 1 ends with “y,” you need to change the “y” to “ie” before adding the “s.” So, instead of writing -ys at the end of the verb, you’ll write -ies. Let’s check out these examples:

II cook.I fry.
WeWe cook.We fry.
YouYou cook. (singular)You cook. (plural)You fry. (singular)You fry. (plural)
He / she / itHe cooks.She cooks.It cooks.He fries.She fries.It fries.
They They cook.They fry.

You can see the pattern: in the present tense, third-person singular subjects — like he, she, and it — have a verb with an “s” at the end. But, if the simple form of the verb ends with “y,” you have to change the “y” to “ie” before adding the “s” at the end of the verb.

Simple Past and Verbs That End With Y

In the simple past, the verb doesn’t change based on the subject. Every subject uses the past form of the verb, which we also call verb 2. Usually, you can build verb 2 by simply adding -ed to the end of the verb. 

Of course, this rule only applies to regular verbs; for irregular verbs like “run,” you must memorize all three forms of the verb.

In most cases, when you’re making the past form of a verb that ends with “y,” you must change the “y” to “i” before adding -ed at the end. Here are some examples:

  • Hurry → hurried
  • Carry → carried
  • Defy → defied

There is one popular exception to this rule, which is that verbs that end with vowel + y don’t change; they take the -ed ending directly after the “y.” One of the most common words in this category is the verb “to enjoy.” 

When a verb ends with a vowel immediately before the “y,” you don’t change the “y” to “i.” Instead, you add -ed directly to the end of the verb. Here are some examples:

  • Enjoy → enjoyed
  • Play → played
  • Destroy → destroyed

Present Participles, Gerunds, and Verbs That End With Y

The present participle is the verb form we use with continuous tenses. We build the present participle by adding -ing to the end of the simple form of the verb. We can construct the gerund, or noun form of a verb, the same way. 

For the present participle and the gerund, there is no need to remove or change the “y” at the end of the verb. Take a look at these examples:

  • Fly → flying
  • Carry → carrying
  • Defy → defying
  • Enjoy → enjoying

If you’re adding -ing to the verb that ends with “y,” you don’t need to change the spelling at all.

Past Participles and Verbs that End with Y

The past participle of a verb, also called verb 3, has special spelling rules for verbs that end with “y.” Since verb 2 and verb 3 are the same for regular verbs, we’ll usually follow the same spelling rules for simple past and past participles for verbs that end with “y.” 

So, when you’re making the past participle (or verb 3) form of a verb that ends with “y,” you must change the “y” to “i” before adding -ed at the end.

The exception about verbs with a vowel directly before the “y” at the end of the word also applies to past participles. So, if you are building a past participle — or using verb 3 — with a verb that ends with vowel + y, don’t change it! These verbs take the -ed ending directly after the “y.” 

When a verb ends with a vowel immediately before the “y,” you don’t change the “y” to “i.”

How Do You Use “Time Flies” in a Sentence?

“Time flies” is already a sentence by itself; you don’t need to add anything to use it properly in a sentence. There are plenty of ways that we might incorporate the sentence “Time flies” into daily English; let’s check out a few of the most popular ways to use “Time flies” in a sentence.

How Do You Describe “Time Flies”?

Dictionaries list “Time flies” as an English idiom that refers to how quickly time seems to pass (source). People use this idiom when they want to show that time has passed more quickly than they expected or without them realizing it. 

Is It Correct to Say, “Time Flies so Fast”?

While there are better ways to express “Time flies so fast” grammatically, this sentence is popular in song lyrics and other artistic uses of English.

It’s quite common to use so and an adverb or adjective together. In this case, we want to describe the verb “flies,” and “fast” can function as an adverb to do just that. Alternatively, we could use the adverb “quickly” (source). 

  • Time flies so fast
  • Time flies so quickly.

However, it might sound a little better if you insert the word “by.”

  • Time flies by so fast.
  • Time flies by so quickly.

Also, while you can use “fast” or “quickly,” you should not use “quick” because it does not function as an adverb in formal English.

How Time Flies

There’s a popular joke among English-speaking kids. It goes like this: “Why did the man throw his clock out of the window? He wanted to see time fly!” 

Of course, when we use the idiom “time flies,” we aren’t talking about a clock literally flying out of a window. Instead, we use the verb “to fly” idiomatically. That means that time is not literally flying; it is moving quickly in a way that we cannot catch it or keep up with it. 

So, when time is passing more quickly than you expected, or if time is passing without you realizing it, you can say that time is flying. Even though time doesn’t fly like a bird or a plane, it goes quickly, and we can’t catch it or contain it; that’s why we say, “Time flies.”

Expressions Using  “Time Flies”

Image by Yan Krukov via Pexels

You will often find the expression “time flies” in several English idioms, proverbs, and jokes. Here are a couple of examples where you can use the phrase “time flies” like a native speaker.

“Time Flies When You’re Having Fun”

This is a proverb that explains how time quickly passes when you’re enjoying yourself. Usually, a native speaker will use this phrase to respond to someone who has just commented on the time. Consider the following conversation to see how you might use it in a similar situation.

Mark:    “Wow! It’s already four o’clock. We’ve been playing this video game for more than two hours.”

Tara:     “Yeah, but we’ve really been enjoying the game. I didn’t notice that the time was passing.”

Mark:    “Time flies when you’re having fun!”

Tara:    “It does, indeed.”

“How Time Flies!”

This short sentence frequently appears as an interjection in a conversation. You might use it after you meet someone whom you haven’t seen for a long time. It has the connotation that you are surprised that so much time has passed since the last time that you met with them. 

Check out this example conversation to see “How time flies!” in action:

Jerry:    Hi Lucy! How are you?

Lucy:    I’m doing well, thanks. How are you? What’s new?

Jerry:    I’m fine, thanks. I’m finally getting used to my new job, so my life is calmer these days.

Lucy:    Oh! I didn’t know that you started a new job. When did you change jobs?

Jerry:    I started my new job about four months ago. I guess we haven’t spoken since then!

Lucy:    Wow, it’s been a long time; how time flies!

Jerry:    Yes, how time flies! Anyway, what’s new in your life?

From this example, you can see how Lucy and Jerry use “How time flies” as an exclamation that also transitions them into the next topic of conversation. 

“Time Flies Like an Arrow; Fruit Flies Like a Banana”

This is a funny pun: it’s a joke that plays with the word “like” and uses the phrase “time flies.” Here, the first half of the sentence is like a proverb that explains how time flies. “Time flies like an arrow” means that time flies quickly and in a straight line. 

This seems like it will be an important piece of advice. However, the second half of the sentence is a joke. Here, “fruit flies” actually refers to the small insects that fly around and love to eat ripe fruits and vegetables. 

And while “like” in the first sentence means “to be similar to,” the second sentence uses “like” to mean “prefer” or “enjoy.” This article was written for

So, when you put the two sentences together, they have different and funny meanings even though they sound very similar. When you tell this joke, your friend might not laugh immediately. If they don’t understand the pun, try explaining it like this: “Time flies like an arrow; fruit flies prefer a banana.”

Final Thoughts

“Time flies” is an English idiom that expresses how quickly time can pass, even if you don’t realize that it’s passing. The correct spelling is “time flies” and not “time flys” because of the rules about spelling verbs that end with “y.” 

In this article, we’ve looked at all of the different rules and exceptions for conjugating verbs that end with “y.” 

Now, check the clock! Did you enjoy learning about verbs and spelling exceptions so much that you forgot about the time? Did time fly while you were learning about verbs that end with “y”? Now you’re ready to use this popular idiom in your conversations and writing, and you’ll sound just like a native speaker.