1. Inviting someone to think rather than stating a fact
Supposing roughly means let us assume that; imagine invites someone to picture a situation; what if asks about a possible scenario. We propose considering a situation that may be realistically possible, unlikely, or purely imaginary. Introducing it does not assert that it happened or definitely will happen.
What if often opens a discussion of a risk or suggestion. Imagine directs attention to a scene or experience; supposing conveniently introduces an assumption before a question about the next steps. These functions overlap. There is no fixed scale on which what if means most likely, supposing less likely, and imagine impossible.
What if the lift stops between floors?
What if the lift stops between floors?
The speaker raises a possible risk rather than announcing an accident.
Imagine you run a small bookshop. How would you choose the books?
Imagine you run a small bookshop. How would you choose the books?
A Present form within an imagined scene can combine with would in the following question.
2. Follow the expression with subject + verb
After supposing, what if, and imagine followed by a finite clause, use ordinary subject → verb order. What if you need help? is already a complete question. Do not import the inversion from Do you need help?: what if does not require do before the subject.
Supposing we need help, who can we call? has two parts. The assumption uses we need; the separate question that follows uses who can we call. Changing the structure should not change the participants: our team should not become your team without a reason.
What if + subject + verb …? / Supposing + subject + verb …, question? / Imagine (that/if) + subject + verb …
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
What if the parcel arrives late?
What if the parcel arrives late?
The order is the parcel arrives; arrives agrees with the singular subject.
Supposing we needed a larger room, who would we ask?
Supposing we needed a larger room, who would we ask?
The condition we needed has ordinary word order; the question who would we ask has inversion.
3. Present forms: an open possibility or concrete suggestion
The Present Simple after these expressions can refer to the future. What if the office closes early tomorrow? considers a possibility for tomorrow, not just the office's routine. Meaning and the time expression guide you, not merely the name of the verb form.
What if we share a taxi? can be a suggestion, while What if the taxi doesn't arrive? can express a concern. The expression is the same; situation and meaning determine the intention. The Present does not prove that the event will definitely happen, or even that it is objectively very likely.
What if we hold the workshop outside?
What if we hold the workshop outside?
This proposes an organizational option rather than announcing an approved decision.
Supposing the café doesn't accept cash, can we pay by card?
Supposing the café doesn't accept cash, can we pay by card?
We consider an open possibility. Doesn't accept preserves the negative meaning; can asks whether card payment is possible.
4. Past forms: distance from reality, not necessarily past time
The Past Simple can present a current or future situation as more imaginary or tentative. What if we invite a speaker? / What if we invited a speaker? offer two perspectives on the same future idea: the second explores the possibility more tentatively.
A Past form does not automatically mean that something can never happen. Supposing the supplier changed the price next week… can refer to a perfectly possible change that the speaker is merely considering. Without context, you cannot determine the exact probability or prove that the Past form describes yesterday.
Would + base form is typical for an imagined result; could expresses possibility, and might a possible, uncertain consequence. These words are not interchangeable without changing the meaning. When an exercise specifies a modal meaning, preserve it.
Supposing our supplier raised the price next week, would we look elsewhere?
Supposing our supplier raised the price next week, would we look elsewhere?
Raised refers to next week; would introduces an imagined response.
Imagine you had an extra afternoon off. You could visit the exhibition.
Imagine you had an extra afternoon off. You could visit the exhibition.
Could names an available possibility without promising that the person will definitely visit the exhibition.
5. Imagine has its own grammatical patterns
Imagine you live by the sea, Imagine that you live by the sea, and Imagine if you lived by the sea are grammatical. That can explicitly introduce the imagined scene; if introduces a hypothetical situation. Do not transfer the warning about redundant if after supposing to imagine if.
In this lesson's standard pattern, say Supposing the weather changes…, without an additional conditional if. Supposing that is also possible. In what if, if is already part of the expression, so do not add another one.
Imagine also takes other patterns: Imagine working by the sea. Here, working is not a finite clause with a separate subject. I imagine the office is open means approximately I think the office is open; it is not the same as an instruction to imagine a situation. This lesson focuses on imagine + finite clause.
Imagine if every meeting lasted only twenty minutes.
Imagine if every meeting lasted only twenty minutes.
Imagine if is an acceptable pattern; lasted gives an imagined perspective.
Imagine that you are the new manager.
Imagine that you are the new manager.
That is optional, and the Present places the role directly within the imagined scene.
6. What follows depends on the intention
After a scenario, you can ask for a decision, suggest a solution, or simply invite reflection. What if the room is full? does not require a continuation with will or would. It is already a clear question about a possible scenario.
Do not mechanically ban Present + would: Supposing we share the cost. That would make it affordable is a natural way to propose a plan and assess its possible consequence. Similarly, do not correct every Past + will combination without examining the time frame and the question's meaning.
A controlled exercise may explicitly require Past Simple and would to practise one pattern. A grammatical alternative that does not satisfy that requirement does not thereby become an error in English.
What if the room is full? We can wait outside.
What if the room is full? We can wait outside.
Can offers a possible solution. The sentence does not assert that no places are currently available.
Supposing we share the equipment. That would reduce the cost.
Supposing we share the equipment. That would reduce the cost.
A Present form in a suggestion and would in an assessment of its result are compatible.
7. Related expressions do not always preserve the same intention
If can neutrally connect a condition and consequence. Supposing more explicitly invites someone to accept an assumption for discussion; what if often opens a question; imagine invites the listener to picture being in a situation. Simply swapping one opening for another does not always preserve the communicative purpose.
In case usually introduces the reason for an advance precaution: Take a charger in case the battery runs out. What if the battery runs out? only raises the risk; it does not say that anyone took a charger. Unless and provided that establish other conditional relationships. Do not add unstated actions or consequences to make them equivalent.
These expressions work well in conversation and informal messages, but they are also allowed in writing. Their suitability for a work discussion depends on tone, audience, and purpose; there is no rule limiting supposing to conversations with friends.
What if the battery runs out during the call?
What if the battery runs out during the call?
A question about a risk, without an added promise or precaution.
Take a charger in case the battery runs out during the call.
Take a charger in case the battery runs out during the call.
This gives advice to prepare. It is grammatical but does not have the same meaning.
8. The boundary with past scenarios and using the patterns yourself
To imagine a different course for an already completed event, use the Past Perfect: What if we had forgotten the keys? This has a different time frame from What if we forgot the keys tomorrow? The lesson introduces this boundary but does not replace full practice of the third conditional.
Before speaking, decide three things: which scenario you are proposing, whether you present it as an open possibility or a more distant assumption, and what response you want from the listener. Then check the subject, negation, and time expressions. You do not need all three expressions in every answer.
We remembered the keys. What if we had forgotten them?
We remembered the keys. What if we had forgotten them?
Had forgotten imagines changing the known outcome of a past event.
Supposing we worked from a quieter place next month, how would that affect our calls?
Supposing we worked from a quieter place next month, how would that affect our calls?
This states a future scenario and an open question for discussion; it does not impose an answer.
Common mistakes
Incorrect:Supposing if the screen freezes, what can we do?
Correct:Supposing the screen freezes, what can we do?
In the standard conditional pattern, supposing already introduces the assumption; an additional if is redundant. This is not a ban on imagine if.
Incorrect:What if does the screen freeze?
Correct:What if the screen freezes?
After what if, use ordinary subject–verb order, not inversion with does.
Incorrect:Imagine we didn't knew the address.
Correct:Imagine we didn't know the address.
After didn't, use the base form know, not knew; preserve the negation.
Incorrect:Supposing the shop closed, what would we bought?
Correct:Supposing the shop closed, what would we buy?
After the modal would, use the base form buy.