Overview
The infinitive of purpose uses 'to + base verb' to explain the reason or purpose of an action. Example: I went to the library to study. It answers the question 'Why did you do it?' For more formal writing, 'in order to' is used. The negative form is 'in order not to' or 'so as not to'.
Purpose structures
- to + verbShe went to the library to study.
- in order toHe saved money in order to buy a laptop. (formal)
- so as toShe spoke quietly so as not to wake the baby.
- so thatThey installed a lift so that elderly residents could reach all floors.
Choosing the right form
- Same subject → use to or in order to: She left early to catch the train.
- Different subjects → use so that: They wrote a guide so that staff could follow it.
- Negative purpose → in order not to / so as not to.
Common Mistakes
- ❌ She studied for to pass. → ✅ She studied to pass.
- ❌ In order to not disturb her. → ✅ In order not to disturb her.
- ❌ So that understand them. → ✅ So that they could understand.
When to use
Explaining goals
She took the course to improve her skills.
Instructions
Press the button to start the machine.
Formal writing
The team met in order to review the findings.
Academic purpose
Data was collected so that trends could be analysed.