Suppose, Supposing, and What If

Suppose, Supposing, and What If: How to Talk About Imaginary Situations in English

English is full of ways to explore ideas, possibilities, and imaginary situations. Three of the most useful (and natural-sounding) expressions for this are suppose, supposing, and what if. We use them when we want to: imagine a situation, consider a possibility, suggest a scenario and think about consequences before something happens.

They are extremely common in spoken English, and they also work beautifully in Cambridge speaking exams, essays, and discussions.

Let’s look at how each one works and how to use them naturally.

Suppose

Suppose means: imagine that something is true or think about this possible situation.

You can think of it as saying:

“Let’s imagine for a moment that…”

Common structure

Suppose + subject + verb…

• Suppose you won the lottery. What would you do first?
• Suppose we miss the last train. How would we get home?
• Suppose he doesn’t agree to the plan. What’s our backup idea?
• Suppose they cancel the flight at the last minute. What then?

In all of these, the speaker is not saying this will happen — only asking the listener to think about the possibility.

In conversation

You’ll often hear suppose used to start discussions:

• Suppose we move the meeting to Friday instead. Would that work?
• Suppose she says no — what’s our next step?

It sounds natural, calm, and slightly thoughtful.

Supposing

Supposing means the same as suppose, but it sounds a little more tentative, speculative and slightly more spoken and conversational

Common structure

Supposing + subject + verb…

or

Supposing (that) + clause…

• Supposing you didn’t have to work, how would you spend your time?
• Supposing it starts raining during the ceremony, what will we do?
• Supposing he never replies, should we contact someone else?
• Supposing they arrive earlier than expected, are we ready?

 With that (optional)

You can also say:

• Supposing (that) she’s right, what does that mean for us?
• Supposing (that) we’re wrong, how serious is the problem?

The word that is optional and often omitted in spoken English.

What if

What if is probably the most common and most natural of the three in everyday English.

We use it to raise a possible problem, imagine a consequence and think about risks and outcomes.

It often carries a feeling of concern, curiosity or planning ahead

Common structure

What if + subject + present simple / past simple…

• What if he doesn’t turn up?
• What if we choose the wrong hotel?
• What if she already knows the truth?
• What if they asked you to move abroad? Would you go?

With past situations (imagining alternatives)

• What if I had taken that job in London?
• What if we had left earlier? We wouldn’t have missed the train.

This is perfect for regrets, alternative histories snd reflective discussions

Are they interchangeable?

In most everyday situations, yes — they are very similar:

• Suppose it rains.
• Supposing it rains.
• What if it rains?

All three invite the listener to think about a possible situation.

However, in real usage:

• What if → sounds the most natural and conversational
• Suppose → slightly more neutral and logical
• Supposing → slightly more tentative and speculative

Very common exam & speaking patterns

These structures are extremely useful for B2–C1 speaking and writing:

What if + present simple → future possibility

What if we fail the exam?

Suppose / Supposing + past simple → imaginary situation

Suppose you lived abroad, would you come back?

What if + past perfect → imaginary past

What if we had listened to her advice?

 Mini comparison in context

Imagine two colleagues planning a presentation:

What if the projector doesn’t work?

Suppose we print the slides just in case.

Supposing they ask difficult questions, who will answer them?

That’s real English. Sensible, practical, and slightly nervous. Just like real life.

Final thought

Suppose, supposing, and what if are small expressions with big power. They let you explore ideas, discuss risks, imagine different futures and sound far more natural and fluent while doing it

If English had a “what-could-possibly-go-wrong?” department, these three would be running it. 😄

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