Into vs In to
Into as one word is a preposition meaning motion towards the inside of something or change from one state to another. In to as two words is two separate words: "in" (often an adverb) followed by "to" (often the start of an infinitive or another preposition). The clearest test: try replacing "into" with "inside of" — if it works, you want one word.
Last reviewed on 2026-04-27.
Quick Comparison
| Aspect | Into | In to |
|---|---|---|
| Form | One word | Two words |
| Function | Preposition (motion or transformation) | Adverb "in" + separate "to" |
| Test | Replace with "inside of" or "toward the inside" | "In" and "to" each have separate jobs |
| Example | She walked into the room. | She came in to grab her bag. |
| Common form of "in to" | (see right) | "In" + an infinitive starting with "to": "come in to talk" |
| Misuse | Writing "into" when adverb "in" + infinitive "to" was meant | Writing "in to" when motion was meant |
Key Differences
1. Different functions
Into is a preposition. It expresses motion towards or transformation. "She poured the milk into the cup." "The caterpillar turned into a butterfly." "He looked into the matter."
In to is two words doing different jobs. "In" is often an adverb (modifying a verb, as in "come in," "turn in"); "to" is a separate preposition or the beginning of an infinitive. "She came in to grab her bag." Here "in" goes with "came"; "to" goes with "grab."
2. The replacement test
Try replacing the word(s) with "inside of" or "toward the inside." If it makes sense, use one word. "He walked into the room" → "he walked inside of the room" ✓
Try saying "in" alone with the verb and "to" alone with the next phrase. If both still make sense as separate elements, use two words. "She came in to talk" → "she came in" + "to talk." Both work; use two words.
3. Worked sentences
"He fell into the pool." (motion towards inside) "She translated the letter into Spanish." (transformation) "Look into it." (idiom — investigate)
"He turned the report in to his manager." ("turn in" + "to his manager") "She came in to say hi." ("came in" + "to say hi") "They went in to see the doctor." ("went in" + "to see")
4. A particularly common error
"He turned the suspect into the police" — wrong; this would mean a transformation. The intended sentence is "turned in to," meaning he handed the suspect over.
"They came into talk about the issue" — wrong; this should be "came in to talk about it." Two separate words.
5. When in doubt
If you can replace with "inside of" or describe motion or transformation, use one word: into.
If "in" attaches to the verb (an action like "come in," "give in," "turn in") and "to" starts a separate phrase, use two words: in to.
6. Phrasal verbs and infinitives
Into is one word in idioms about motion or change: look into, run into, get into, transform into, divide into.
In to is two words when "in" is part of a phrasal verb (turn in, come in, drop in, give in) and "to" is part of what follows. Recognising phrasal verbs is the key.
When to Choose Each
Choose Into if:
- Motion towards the inside of something — physical or metaphorical.
- Transformation: "turned into," "changed into," "divided into."
- Idioms: "look into," "run into," "get into."
Choose In to if:
- When "in" pairs with a verb and "to" begins a separate phrase or infinitive.
- "Turn in to" (turn in + to whom), "come in to" (come in + to do something).
- When the test "inside of" doesn't work.
Worked example
"She walked into the office, then went straight in to see her boss." Two uses in one sentence: the first describes motion (into the office); the second is "in" attached to "went" plus "to" introducing an infinitive (to see her boss).
Common Mistakes
- "They're always interchangeable." Different forms with different functions.
- "Always use one word." The two-word form is correct in many sentences.
- "He turned himself into the police." Means "he transformed himself into the police" — almost certainly not what you meant. Should be "in to."