To vs. Too
“To” and “too” sound alike but have different grammatical jobs. “To” functions as a preposition and in the to-infinitive, while “too” is an adverb that can mean “also” or “more than enough.”
Use “to” as a preposition or infinitive marker; use “too” for meanings such as “also” or “more than enough.”
Key details
Choose the right form
| Meaning/job | Use | Decision |
|---|---|---|
| destination, receiver, relation, or infinitive marker | to | Use the preposition/infinitive form. |
| also / as well | too | Use the adverb. |
| excessive degree / more than enough | too | Use the adverb before the relevant adjective/adverb or complement. |
Quick tests
Also-or-excess test
Can the word be replaced by “also” or does it mean an excessive degree?
If yes: Use “too.”
If no: Check whether the word is the preposition or infinitive marker “to.”
Caveat: The forms are homophones in ordinary speech, so sound alone cannot decide the spelling.
Examples
Send the invoice to the accounts team.
“To” marks the receiver/destination.
I want to check the totals again.
“To” introduces the infinitive “check.”
The file is too large, and the backup is too.
The first “too” marks excess; the second means “also.”
Further guidance
Core difference
Use “to” before a destination/receiver or as part of a to-infinitive; use “too” for “also” or for excess/degree.
Fast Test
If you can substitute “also” or “more than enough,” choose “too.” Otherwise check whether the word is the preposition/infinitive marker “to.”
Usage Boundary
The words are homophones in ordinary pronunciation, so sound alone cannot choose the spelling.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- to — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct grammar-reference evidence that to functions as a preposition and as the marker in the to-infinitive.
- too — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct dictionary and grammar evidence for too as an adverb meaning more than enough, also, or related degree senses.