Be supposed to: expected behaviour, a rule, or an arrangement
The basic idea: what is expected, not necessarily what happens
Be supposed to names what is expected under a rule, instruction, arrangement, or schedule. It does not confirm that the expectation is fulfilled, but it does not necessarily imply a breach either: it is often a neutral statement of what is expected.
Compare the simple present, which states a fact or habit without this distinction between expectation and possible deviation. Everyone wears casual clothes on Fridays describes a habit; Everyone is supposed to wear casual clothes on Fridays identifies a workplace arrangement that someone might not follow.
Guests are supposed to switch their phones to silent during the ceremony.
Guests are supposed to switch their phones to silent during the ceremony. (This is the expected practice.)
This describes the expected behaviour of guests, not the fact that everyone actually does it.
The software update is supposed to take about ten minutes to install.
The software update is supposed to take about ten minutes to install. (This is the estimate.)
A technical time estimate, not a guarantee: the actual time may differ.
Meaning 1: a rule or social norm
Be supposed to most often describes a general rule, instruction, or social norm: what people are expected to do in a place, organisation, or culture. The source of the rule is rarely stated explicitly; it is enough that the rule exists and is known to those involved.
Such rules can be formal, such as regulations or job instructions, or informal, such as etiquette or custom. The form is the same in both cases: subject + am/is/are + supposed to + base verb.
Recruits are supposed to salute senior officers.
Recruits are supposed to salute senior officers. (Under the regulations.)
A formal regulatory requirement applying equally to all recruits.
Lab visitors are supposed to knock before entering.
Lab visitors are supposed to knock before entering.
An accepted standard of behaviour in this particular place, not a general law.
Meaning 2: an arrangement, plan, or schedule
The second meaning concerns a particular arrangement, plan, or schedule rather than a lasting rule: something is expected to happen at a certain time or in a certain way, though it is not yet a confirmed event.
The train is supposed to arrive at nine refers to the expected time under a plan or timetable. The train will arrive at nine presents the arrival as a prediction or confident statement; will itself does not provide a 100% guarantee.
The shipment is supposed to arrive on Thursday.
The shipment is supposed to arrive on Thursday. (According to the schedule.)
The date comes from the logistics plan, not a confirmed arrival.
We're supposed to meet the contractor at noon.
We're supposed to meet the contractor at noon. (As arranged.)
An agreed meeting time that either side could still reschedule.
The underlying distinction: expectation versus fact
Is/are supposed to distinguishes an expectation from a report that an action has been performed. If reality differs, add but or though to explain the discrepancy explicitly. Without that context, do not automatically assume that the rule has been broken.
A contrasting continuation is optional. We’re supposed to meet at noon can simply remind someone of a current arrangement.
The festival is supposed to end at midnight, but the headliner hasn't even started.
The festival is supposed to end at midnight, but the headliner hasn't even started.
The continuation with but explicitly shows a discrepancy between the plan and the current situation.
Deliveries are supposed to stop at six, though the warehouse sometimes accepts late vans.
Deliveries are supposed to stop at six, though the warehouse sometimes accepts late vans.
Though signals the same kind of discrepancy with a different discourse marker.
Form: is/are supposed to + base form
Be agrees with the subject: I am, he/she/it is, you/we/they are. The basic pattern then has supposed to + base form. An adverb can intervene: You are still supposed to attend.
In a complete sentence, do not omit be or to, or use -ing after to: Guests are supposed to arrive. However, guests supposed to arrive can be part of a longer noun phrase; here we practise complete sentences.
Subject + am/is/are + supposed to + base 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.
- V1 / base form —
- The base verb without to: work, go, be.
I am supposed to submit the form by Monday.
I am supposed to submit the form by Monday.
The subject I agrees with am, followed by the base verb submit without -ing.
The trainees are supposed to wear helmets on site.
The trainees are supposed to wear helmets on site.
The plural subject trainees agrees with are, followed by base-form wear.
Who sets the expectation? An unnamed source
Unlike sentences explicitly naming who requires something, such as My manager asked me to… or The company requires…, be supposed to usually leaves the source of the expectation unnamed. It may be a rule, custom, plan, or even general common sense; the source is simply understood.
Leaving the source unnamed is useful for general standard requirements in announcements, instructions, and official reminders, where the content of the rule matters more than who created it.
Employees are supposed to badge in at the main entrance.
Employees are supposed to badge in at the main entrance.
The sentence does not say who established the requirement; it simply states the current norm.
Gallery visitors are supposed to keep a respectful distance from the artworks.
Gallery visitors are supposed to keep a respectful distance from the artworks.
Again, no particular person or authority is named, only the norm itself.
Spelling: supposed, not suppose
Supposed in this construction is always spelt with final -d, even when it is not clearly audible after is/are/am/was/were. Suppose without -d is a separate verb meaning think or assume: I suppose you're right.
Final consonants may be indistinct in fast speech. Check the spelling against the construction: be supposed to requires supposed with -d, while I suppose uses the verb suppose.
I suppose the manager already knows about the delay.
I suppose the manager already knows about the delay.
Suppose is a separate verb meaning think or assume here, without -d and without to + base verb following it.
She's supposed to check in by nine.
She's supposed to check in by nine.
Here supposed is part of the fixed construction be supposed to and always has -d.
Questions: Is/Are … supposed to…?
Form a yes/no question by ordinary inversion of be: move it before the subject, while the rest of the construction, supposed to + base verb, remains after the subject.
For a wh-question, place the question expression before the inverted structure: What time is the shuttle supposed to leave? If who is itself the subject, there is no separate inversion: Who is supposed to call?
Are guests supposed to sign the guest book?
Are guests supposed to sign the guest book?
Question order: be moves before the subject.
What time is the shuttle supposed to leave?
What time is the shuttle supposed to leave?
A wh-question: question expression + be + subject + supposed to.
The limits of the topic: what this rule does not cover
The main focus here is the present affirmative form and questions about expectations. Not supposed to and was/were supposed to are treated separately. The past form names a past rule or expectation and does not itself prove that it was broken or unfulfilled.
The related construction be meant to, with its sense of intention or purpose, is covered in the separate rule Be meant to as a synonym. Must, have to, and should, as well as reported reputation such as is supposed to be haunted, also remain outside this rule.
The team is supposed to submit the proposal today.
The team is supposed to submit the proposal today.
Unlike negative not supposed to or past wasn't supposed to in the neighbouring rule, this is the current affirmative present form.
Common mistakes
Incorrect:You're suppose to greet the front-desk staff before going upstairs.
Correct:You're supposed to greet the front-desk staff before going upstairs.
Supposed always has final -d in this construction; suppose without -d is a separate verb meaning think or assume and does not fit here.
Incorrect:Drivers supposed to check their mirrors before reversing.
Correct:Drivers are supposed to check their mirrors before reversing.
In this complete-sentence pattern, supposed to follows a form of be, such as am/is/are; it is not an independent modal verb.
Incorrect:The photocopier is supposed to warming up before the first print.
Correct:The photocopier is supposed to warm up before the first print.
Supposed to takes a base verb, not an -ing form.
Incorrect:Trainees are supposed introduce themselves before the first shift.
Correct:Trainees are supposed to introduce themselves before the first shift.
To is required between supposed and the base verb; without it, the construction is incomplete.
Incorrect:The house rules is supposed to protect everyone equally.
Correct:The house rules are supposed to protect everyone equally.
The subject the house rules is plural, so it needs are, not is.