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“Let that sink in”: Here’s What This Expression Really Means

“Let that sink in”: Here’s What This Expression Really Means

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What does it mean to say “let that sink in”?

English has some odd phrases that are used on a daily basis.

Most people never think about these and use them all the time. This can be very confusing if you’re unfamiliar with the phrase in question.

In this article, we’ll explain what “let that sink in” means and how to use it.


What is the meaning of “let that sink in”?

The meaning of “let that sink in” is “think about that for a while.” It is an idiomatic way of saying something for effect. When someone says, “let that sink in,” they tell you to reflect on what you have just learned. “Let that sink in” is rather informal and should not be used in formal contexts. 


Different meanings of “let that sink in”

Although the same basic meaning of “think about that” is true for any use of this phrase, it can carry different nuances in different situations.

If someone is telling you something shocking, “let that sink in” might be an invitation to consider all the ramifications of what you have just learned.

On the other hand, if a teacher wants to make sure you understand a new piece of knowledge, they might say the phrase to suggest that you need to make sure you’ve memorized it before they can move on in their lesson.

Learning the difference between a clause and a phrase might not be mind-blowing, for instance, but because it’s confusing you might need to think about it a while to ensure you get the terms right.



The Earth orbits the Sun at more than 18 miles per second. That means it travels the distance from New York to London in 193 seconds, or just over three minutes. Pause for a moment to let that sink in.”


“Intransitive verbs never take a direct object. Let’s let that sink in for a moment, and we’ll move on.”

In the first example, the phrase “let that sink in” is used because it’s surprising to think how fast the Earth is moving through space.

Our first instinct is to dismiss the knowledge because we can’t easily picture it, so we have to pause and think it over until it has “sunk in” to our brain.

In the second example, intransitive verbs are not quite as exciting as the speed of our planet. All the same, intransitive verbs are important to understanding grammar.

Anyway, we can imagine that the speaker is a teacher delivering a lesson about verbs and that they want their students to understand intransitive verbs before explaining other types of verbs.

“Just let that sink in” is a slightly different variation of “let that sink in” that you will also often come across. It makes things yet a bit more dramatic. See the example below:

Person A: “Did you know that the universe is constantly expanding?”
Person B: “Wait, what? I’ve never heard that before.”
Person A: “Yeah, it’s mind-boggling, right? Just let that sink in.”



When not to use “let that sink in”

Metaphors like “let that sink in” can be used in pretty much any context.

Like most forms of poetic language, however, they are best used sparingly.

If you say “let that sink in” after every new fact you give someone, they will quickly lose track of what parts you’re trying to emphasize.

Additionally, because this phrase implies that something you are saying is important, it doesn’t make sense to use it for trivial comments.

If you were to say, “I’m going to cook an egg. Let that sink in.” the implication is that it’s very unusual indeed for you to cook an egg.

Finally, there may be some academic contexts in which this kind of metaphorical writing is discouraged.

“Let that sink in” isn’t a very formal phrase, so if you’re writing a college paper or other document where you need to use formal language, you shouldn’t use it.

Instead, you might try the phrase “This can’t be overstated,” which accomplishes the same thing but is less poetic in nature.