Decisions I

There are three ways to express decisions: I will, I am going to & I was going to.

Of course you can also say, I decided to or I have decided to, but using will and going to is more usual.

Decision now = I will

Use future simple to express an action in the future.
The future simple is also used to express a decision that is made now, often as a reaction.

subject + will + infinitive without to

You see an old person with a heavy suitcase near the stairs. You say:
O: I’ll help you
X: I help you
X: I am helping you

Reminder: I will (formal) = I’ll (casual)

When you decide to do something, even if the action starts as you say it, we still use the future simple.

– I woke up late, please tell the tournament organiser!
X: OK, I do that!
O: OK, I’ll do that!

– Well, it’s late, I have to go.
X: I call a taxi.
O: I’ll call a taxi.

-You’ve forgotten to register.
-Ah, I’ll do that now.

As a reaction, use future simple to express a decision made now.

No, I won’t give you my ice cream!

Decision before = I’m going to

I’m going to watch the next episode right now!

This is different to the future simple. This expresses a decision that was made in the past.

subject + (to be) + going + (to infinitive)

I am going to watch the next episode = I have decided to watch the next episode. I am expressing the decision was made before speaking.

“I have decided to” is the same as I am going to, but it is more formal.

I will watch the next episode = I decided now / as I speak, or just before.

I’m going to go to the cinema
I’m going to kill you!

Notice the difference!

I’ll kill you
I’m going to kill you

Both can be said as an immediate response –
but the first shows the action in the future or a decision made now while the second shows a decision made in the past.

Usage

Furious, not thinking, snapping, violent, aggressive : I’ll kill you

Thinking, planning, threatening, incredulous: I’m going to kill you

Future vs Continuous action
Plans
Decisions I
Decision II
Opinions / Predictions
Future Perfect

Credits / Sources:

Cambridge English Grammar in Use by Raymond Murphy
Cambridge CELTA