What either … or means
In the basic model, we combine two alternatives with either … or: either introduces the first, and or introduces the second. These can be things, attributes, actions, or entire clauses.
The sentence presents potential options. Whether they are mutually exclusive depends on the meaning: we usually choose one dress color from two, but an invitation to call or write does not necessarily forbid you from doing both.
either + option A + or + option B
For lunch today, either the soup or the sandwich sounds good to me.
For lunch today, either the soup or the sandwich sounds good to me.
Both options are noun phrases; either stands directly before the first one.
We could paint the fence either grey or dark green.
We could paint the fence either grey or dark green.
Color adjectives also form an acceptable pair of options for either … or.
You could either take the early train or wait for the next one.
You could either take the early train or wait for the next one.
Two actions of the same subject you are combined: take and wait follow could.
Where to place either and or
The clearest order for learning is: shared subject and auxiliary verb, then either before the first action and or before the second: She will either call or write.
When connecting subjects or full clauses, either can start the sentence: Either Maria or her assistant will help. In natural speech, the position of either can be more flexible; not every shift is an error.
The position of either sometimes shifts slightly between neighboring words without changing the meaning (e.g., before an entire prepositional phrase or only before a noun within it)—both options remain natural, as long as or introduces the second option in the same form.
Maria will either call you tonight or send a message tomorrow.
Maria will either call you tonight or send a message tomorrow.
Either stands after the shared subject and auxiliary verb will, before the first verb phrase.
Either Maria or her assistant will handle your request.
Either Maria or her assistant will handle your request.
Here, the options are the subjects themselves, so either stands at the beginning of the sentence.
Either the printer is broken, or someone forgot to switch it on.
Either the printer is broken, or someone forgot to switch it on.
Both options are full sentences (subject and predicate), so either begins the first one.
Parallel structure
Both parts after either and or must fit the shared sentence structure. A convenient model is two nouns, two verb phrases, two adjectives, or two parts with their own subjects and verbs.
The most common mistake is to combine a verb phrase with a gerund or a full subject. It is easy to check: mentally read each option separately, inserting it into the main part of the sentence.
The museum is open either on weekdays or on public holidays.
The museum is open either on weekdays or on public holidays.
Both options are identical prepositional phrases with on.
You can either renew your membership online or visit the front desk.
You can either renew your membership online or visit the front desk.
Both options are verb phrases with the verb in its base form after can.
Verb agreement when either … or connects subjects
When either … or connects subjects, in academic and formal writing, agree the verb with the one closer: Either the landlord or the tenants pay. If combining different numbers sounds awkward, you can reorder the options or reconstruct the sentence.
This is easy to check by ear: mentally cover the first subject and see if the verb agrees with the one remaining.
either + subject A + or + subject B (closer) + verb, agreed with subject B
- 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.
Either the tenants or the landlord pays for the repair.
Either the tenants or the landlord pays for the repair.
The closer subject is the landlord (singular), so the verb pays is also in the singular.
Either the landlord or the tenants pay for the repair.
Either the landlord or the tenants pay for the repair.
Now the closer subject is the tenants (plural), so the verb pay is in the plural.
Comma between parts
When either … or connects two short parts within a single sentence (two nouns, two verb phrases), a comma is not needed.
When either … or connects two full clauses (each with its own subject and predicate), a comma is usually placed before or—this helps the reader see the boundary between the two option-sentences.
We can meet either at my place or at the office.
We can meet either at my place or at the office.
A short pair of prepositional phrases—no comma is needed before or.
Either you send the confirmation today, or the booking will be cancelled automatically.
Either you send the confirmation today, or the booking will be cancelled automatically.
Two full clauses—the comma before or marks the boundary between them.
Functions in speech: choice, warning, question
Most often, either … or simply offers a neutral choice between two acceptable options: both are suitable, and the decision is up to the listener.
The same construction often conveys a warning or a condition with a consequence: the first option is the desired action, and the second is the unwanted result if the first does not happen.
Either … or also naturally fits into a question or offer when the speaker names two options and expects a response.
You can pay either now or at checkout — it's up to you.
You can pay either now or at checkout — it's up to you.
Neutral choice: both options are acceptable.
Either you turn down the music, or I'm calling building security.
Either you turn down the music, or I'm calling building security.
Warning: the second option is an unwanted consequence if the first does not occur.
Could we sit either in the shade or indoors?
Could we sit either in the shade or indoors?
Asking whether one of the suggested places is possible. For a direct choice, you can say 'Would you rather sit in the shade or indoors?'
Limits: number of options and related constructions
In this lesson, we are practicing the basic pair of two options. A longer list is often most easily formatted with a simple or before the last item: cake, ice cream, or fruit.
Either … or also occurs with longer lists. The mere fact that a third option is present should not be marked as a grammatical error.
Do not confuse either … or with related pairs: both … and adds both facts at once, and neither … nor negates both at once. These two pairs have their own grammar and are not included here.
Separately, there is the independent word either without or (e.g., in short answers like 'Either is fine' or in the sentence 'I don't like it either')—this is a different construction with its own grammar, not covered here.
For the team lunch we can order either pizza or salad.
For the team lunch we can order either pizza or salad.
Exactly two options—a pure form of the construction.
For the team lunch we can order pizza, salad, or sandwiches.
For the team lunch we can order pizza, salad, or sandwiches.
A simple way to list three options—commas and or before the last one.
Common mistakes
Incorrect:She will either calls the plumber or fixes the leak herself.
Correct:She will either call the plumber or fix the leak herself.
After the shared will, both actions must have the base form: call and fix.
Incorrect:For dessert we can order either cake nor fruit.
Correct:For dessert we can order either cake or fruit.
Either is paired with or. Nor belongs to the negative pair neither … nor.
Incorrect:Either you send the invoice now and I will call the client myself.
Correct:Either you send the invoice now, or I will call the client myself.
The second part of the either … or pair is always introduced by or, not and; the conjunction and does not show a choice between two options.
Incorrect:You can either bring your own laptop or borrowing one from the office.
Correct:You can either bring your own laptop or borrow one from the office.
Both options after either / or must have the same grammatical form; here the first is a verb phrase with the base form (bring), so the second must also be a base form (borrow), not a gerund (borrowing).
Incorrect:Either the manager or the assistants is available this afternoon.
Correct:Either the manager or the assistants are available this afternoon.
When either … or connects two subjects, the verb agrees with the subject closer to it; here the closer subject the assistants is plural, so the verb are is required.