Purpose: in order to / so that

To give a purpose — why someone does something — English has several options. The key is what comes next: a verb, a clause (subject + verb) or a noun.

💡A very common mistake is for + verb for purpose (I came here for learn English). Use to / in order to with a verb: I came here to learn English. For goes with a noun: I came here for the course.

1. To + verb — the most common way, especially in speech

• I called the shop to check if they had my size.

• Why are you learning English? — To get a better job.

2. In order to / so as to — stress the purpose, more formal. Common in writing, work emails and presentations; so as to is a little more formal still.

• Minh moved to Hanoi in order to find work.

• Staff must wear gloves so as to protect their hands.

3. Negative: in order not to / so as not to + verb — not goes before to.

• I set two alarms in order not to miss my flight.

• She whispered so as not to wake her parents.

💡Plain not to on its own sounds awkward for purpose (I left early not to miss the bus). Say so as not to, in order not to, or so that … won't / wouldn't.

Use so that when a subject + verb follows — especially when the purpose is about someone else, or you need can / will. Purpose now or in the future → can, will (or the present simple); purpose in the past → could, would.

• I'll send you a map so that you can find the house easily.

• Take an umbrella so that you don't get wet.

• Dad bought a bigger car so that we could travel together.

  past → could

• We spoke quietly so that we wouldn't wake the baby.

  past → wouldn't

In informal speech you can drop that: Speak up so everyone can hear. Don't confuse this with , so (therefore), which shows a result: I was tired, so I went to bed. — that is not a purpose.

To say that someone or something must do the action, use in order for + person / thing + to + verb (formal): In order for the plan to work, everyone has to help.

• We stopped for petrol. = We stopped to get petrol.

• This app is for booking train tickets.

  what a thing is used for

• ✗I came here for learn English.

  ✓I came here to learn English.

  Purpose with a verb → to + verb, not for.

• ✗She works two jobs for paying her rent.

  ✓She works two jobs to pay / in order to pay her rent.

  For + -ing describes what a thing is for, not why a person acts.

• ✗Speak slowly so that everyone understand.

  ✓Speak slowly so that everyone can understand.

  So that + subject + can/will…

• ✗We left at 5 a.m. so as not miss the boat.

  ✓We left at 5 a.m. so as not to miss the boat.

  The full phrase is so as not to + verb.

• ✗Yesterday we took a taxi so that we can arrive on time.

  ✓Yesterday we took a taxi so that we could arrive on time.

  Past → could.

• ✗I left early not to miss the bus.

  ✓I left early so as not to / in order not to miss the bus.

  Plain not to sounds awkward for purpose.