Will vs. Be Going To: Decisions, Promises, Plans, and Predictions

When you talk about the future, you often have several possible forms. Your choice helps the listener understand whether you are offering help, describing an intention, reporting an arrangement, or making a prediction.

Start with this useful distinction: will often introduces a decision or commitment; be going to often describes an existing intention. Both also express predictions. They do not represent fixed percentages of certainty.

1. A practical guide

Your purpose	Common choice	Example
Make a decision during a conversation	will + base verb	I’ll book a table.
Offer help or make a promise	will + base verb	I’ll send you the details tonight.
Describe something you already intend to do	be going to + base verb	I’m going to take Friday off.
Say what you expect to happen	will + base verb	I think the interview will go well.
Predict an outcome from the current situation	be going to + base verb	We’re going to miss the train.
Describe an arrangement	present continuous	I’m having lunch with a client tomorrow.
Give a timetable or scheduled event	present simple	The seminar starts at ten tomorrow.

These are common patterns, and some overlap. Choose the form that fits your message and the conversation.

2. Build the forms correctly

Sentence type	will	be going to
Statement	She will call you.	She is going to call you.
Negative	She won’t call you.	She isn’t going to call you.
Question	Will she call you?	Is she going to call you?

Use the base verb after both will and going to: will call, going to call. Change be to match the subject: I am, she is, we are.

Common mistake	Correct form
She will calls you.	She will call you.
I’ll to send it.	I’ll send it.
I going to apply.	I’m going to apply.
We’re going to late.	We’re going to be late.

In conversation, contractions are common: I'll, you'll, we'll, and won't (= will not).

3. Will: respond, offer, and commit

A decision made during the conversation

A: We haven’t booked a restaurant yet.
B: I’ll book one now.

B responds to the problem and takes responsibility for the booking.

A: I can’t read the menu without my glasses.
B: I’ll read it to you.

Here, will makes a natural offer of help.

A promise can involve an earlier plan

I’ll call you as soon as I get home.

You may already have planned to call. You can still use will because you are now making a commitment to the listener. The rule “will always means a brand-new decision” is too restrictive.

I won’t share your phone number.

This can be a promise. In other contexts, won't can express refusal, so pay attention to the situation.

4. Be going to: intentions and present evidence

An intention you already have

I’m going to look for a new apartment next month.

You have already formed this intention. You do not need to have booked any apartment viewings.

We’re going to spend less on eating out this month.

This describes a plan. It does not guarantee success or mean that the plan cannot change.

A prediction based on the current situation

The traffic isn’t moving. We’re going to be late.

Being late is an expected result, not an intention.

That glass is too close to the edge. It’s going to fall.

The speaker uses something visible now to predict what comes next.

5. When both forms work

Predictions often overlap

With will	With be going to
I think you’ll enjoy the workshop.	I think you’re going to enjoy the workshop.
It’ll be a busy week.	It’s going to be a busy week.

Both versions can be natural. Going to often highlights what you already know about the situation, such as the workshop content or a full calendar. Will presents the prediction more directly as your expectation.

Evidence does not make will incorrect. Also, I think works with either form.

The same action can be a promise or a plan

I’ll send you the report tomorrow.
I’m going to send you the report tomorrow.

The first readily works as a commitment to the listener. The second describes your intention. Both can refer to exactly the same report and delivery date.

However, the forms do not always perform the same conversational job. If a colleague is struggling with a box, I'll carry that for you is a natural immediate offer. I'm going to carry that for you announces an intention and is less natural as a spontaneous offer in that situation.

6. Other ways to talk about future plans

Present continuous: arrangements

I’m meeting a client at two tomorrow.
We’re having dinner with some friends on Saturday.

The meetings have been arranged. A future time expression or the surrounding conversation makes the future meaning clear.

Compare:

Sentence	Focus
I’m going to see the dentist next week.	Your intention; the sentence does not specify whether you have an appointment.
I’m seeing the dentist at three on Tuesday.	An arranged appointment.

An arrangement can still change. The present continuous does not mean “100% certain,” and it is not a general substitute for future predictions.

Present simple: timetables and schedules

My flight leaves at 7:30 tomorrow morning.
The conference ends on Friday.
What time does the seminar start?

These sentences present scheduled events as facts. I work tomorrow is also natural when reporting your work schedule.

The base form and the present simple are different concepts. The base form is leave. In a present simple statement, a third-person singular subject takes leaves: My flight leaves. After does, use the base form: When does it leave?

For a newly formed personal intention, I'm going to look for a new job is a more useful starting point than simply putting the verb in the present simple.

Present forms after when and if

I’ll message you when I arrive.
If it rains tomorrow, I’ll take a taxi.

In clauses that give a future time or condition, we normally use a present form rather than will: when I arrive, not when I will arrive.

This does not apply to every sentence containing when. The direct question When will you arrive? correctly asks about a future arrival.

7. Ask about intentions or make a request

Question	Common purpose
Will you send me the address?	Request an action.
Are you going to send me the address?	Ask about the person’s intention.
Are you meeting anyone after work?	Ask about arrangements.
What time does the seminar start?	Ask about a schedule.

For a softer request, try Could you send me the address, please? Tone and context matter: a question about intentions can also sound like a reminder or a complaint.

For more on question structure, see Questions with Question Words.

8. Practise with everyday situations

Cover the suggested answers and say your own response aloud. More than one answer may work; aim to communicate the purpose in the first column.

Situation and purpose	Suggested answer
The phone rings. Volunteer to answer.	I’ll get it.
A colleague needs help carrying a box. Offer help.	I’ll carry that for you.
You have already decided to join a gym. Tell a friend.	I’m going to join a gym next month.
You have a confirmed lunch appointment tomorrow. Describe it.	I’m having lunch with a client tomorrow.
Your train’s departure is printed on the timetable. Report it.	Our train leaves at 8:15.
Traffic has stopped. Predict the result.	We’re going to be late.
Reassure a friend about a course you think suits them.	I think you’ll enjoy it. / I think you’re going to enjoy it.
Promise to contact someone after reaching your hotel.	I’ll message you when I get to the hotel.

Try changing the message: turn I'm going to send you the quote tomorrow into a promise to the customer. Then turn I'll call the restaurant into a report of an intention you formed earlier. Notice how the event can stay the same while your purpose changes.

References

Examples and practice activities were written for this article. Grammar references checked on October 27, 2026: