Word Choice: Into vs. In To

In speech, the distinction between “into” (one word) and “in to” (two words) is pretty easy to miss. As a result, “into” and “in to” are often (wrongly) used interchangeably in writing.

However, there is a difference between these terms. And while this isn’t exactly the worst grammatical error you could make, you’ll want to avoid confusing “into” and “in to” in formal or academic writing to ensure clarity.

Into (Movement and Change)

The preposition “into” has various uses, but most fall under the following categories:

1. Expressing movement towards or entering something (e.g., “Bob climbed into the box”);
2. Indicating a change in state (e.g., “The chemical turns into a gas when heated”);
3. Meaning “about” or “relating to” something (e.g., “An inquiry into spending habits”);
4. Showing interest in something (e.g., “I’m really into yoga these days”).

The first of these covers physical movement, but can also include continued movement towards a specific point in time:

She worked deep into the night to solve the problem.

Likewise, when used to describe a change, this can be physical, but it can also be something more abstract, like a change in emotional state or translating something “into” another language.

Importantly, all of these relate to movement, action or change.

In To (Part of a Verb Phrase)

As the variety of definitions above might suggest, using “into” is correct a lot of the time. The main exception to this is when “in” appears next to “to” in a sentence as part of a phrasal verb, which is when “in” is used with another word to create a verb phrase, such as “break in” or “drop in.”

This can be confusing when “in” is followed by “to,” as the temptation is to combine these as “into.” But when “in” is part of a verb phrase, it needs to be kept separate from the preposition “to”:

I stepped in to separate the fighters. – Correct

I stepped into separate the fighters. – Incorrect

Here, for instance, the verb phrase “stepped in” (meaning “intervened”) is treated as a single element in the sentence, with “to” a preposition indicating the reason for acting.

Saying “I stepped into separate the fighters,” on the other hand, doesn’t make sense. This is because the preposition “into” implies entering something, but “separate the fighters” doesn’t follow from this.

Into or Into?

As mentioned above, a lot of the time “into” is the correct term to use when describing a movement, action or change. In these cases, “into” is a single preposition.

This is different when we use “in” as part of a phrasal verb followed by “to,” since here we are not using “in” as a preposition in the sentence. Keeping “in” and “to” separate in these cases helps to ensure clarity, as it clearly shows the structure of the sentence. Remember:

Into = Preposition indicating movement, action or change

In to = Part of a verb phrase