The difference between 'extra chair' and 'spare chair'

Question

I was talking to one of my friend about a student who came in to our class and took an extra chair away. My friend corrected me and said, "you mean a spare chair?" and I replied, "yes we have so many of them in our class and they're taking up a lot of room." I didn't ask him if there was any difference between an extra chair and a spare chair.

I looked up the words and I don't see any difference at least in this context! Was he right to correct me? Is there really a difference?

If as a student you need a chair and you wonder if some are available in other classrooms and you go knock at the door of one, what would you say?

I wonder if there is an extra chair I could borrow.

Or

I wonder if there is a spare chair I could borrow.

Answer 1

Neither is wrong, but your use of "extra" is what I would expect. "Spare" is fine, but I would use "extra" in that case.

As a native speaker (primarily American English with significant influences from British English), I tend to think of "spare" by the first meaning typically listed:

kept in reserve, as for possible use
dictionary.com

kept as something extra that can be used if it is needed
Merriam-Webster

Contrast with "extra":

beyond or more than what is usual, expected, or necessary; additional
dictionary.com

more than is due, usual, or necessary
Merriam-Webster

The difference is that spares are kept intentionally to be used when there's an excess/unusual need. Cars carry a spare wheel, not an extra wheel, but they frequently have extra seats (seats not currently occupied).

The chairs in your classroom aren't spare in the first sense; that is, they aren't specifically being kept in reserve. They are extra in that you have more chairs in the classroom than you currently need.

But note that "spare" has a second meaning which is essentially synonymous with "extra":

being in excess of present need; free for other use
dictionary.com

not needed by you and available to be shared or given to someone else
Merriam-Webster

So it's fine to use "spare" in this case, but "extra" is at least as correct if not ever-so-slightly more so.

Answer 2

Let's say you are holding a meeting, and there are 10 chairs, but only 9 people show up. Then you can say:

I seems like we have one extra chair.

It is available but nobody is sitting in it.

But if 11 people show up, then you can say to the 11th person:

Please wait a minute, I will get a spare chair from the storeroom.

It is available, but there is no intention to use it without some special circumstance occurring.

A auto spare tire is used in this context, as an extra tire only used if an existing one is damaged.

Answer 3

"Extra" means "one/some more than is needed", whereas "spare" means "one/several from not taken up so far".

Answer 4

There may be some misunderstanding where saying you would get them an extra chair might suggest that they have already taken one chair and you are getting them an additional extra chair.

I don't think it was worth correcting though, both are very easily understood and reasonably interchangeable in this context though I think I would naturally say spare chair.

Answer 5

In this context, the difference really depends on the availability of a chair to be loaned out, allowed to be borrowed, given away: in short, dispensed with. Any chair that meets that criterion is a spare chair, whether it's an extra chair or not.

An extra chair is one that is not in use. You can consider it one more than is necessary or required, and as a "left over" chair.

A classroom with 10 students and 11 chairs has an extra chair; call it Room 1. A classroom with 10 students and 15 chairs has five extra chairs; call it Room 5.

Now someone can go to either classroom and ask to borrow one of the extra chairs. There is no problem with that. So the question

I wonder if there is an extra chair I could borrow.

is valid and doesn't go against the meaning of what an extra chair is. And it doesn't violate the use, semantics or grammaticality of English.

But you basically need the phrase [that] I could borrow, because extra does not include that concept as intrinsic to its meaning.

Now before we talk about the adjective spare chair, let's bring up a definition for the verb to spare. There are many meanings, some of them seemingly contradictory and/or near antonyms (the verb's been in use since Old English). But one that is common is

8a. To dispense with from one's stock or supply, or from a number, quantity, etc.; to part with, to give or grant, lend, etc., to another or others, especially [but not necessarily] without inconvenience or loss to oneself; to do without.

(Oxford English Dictionary)

So, a spare chair is a chair that can be spared. Or it is a chair that one can "dispense with...blah blah blah, that whole definition above"

In fact the OED does define the adjective spare using the verb spare:

2a. That can be spared, dispensed with, or given away, as being in excess of actual requirements; superfluous.

Now, a spare chair is not the same as an extra chair. In fact, a spare chair could be not an extra chair. Let me restate that: A spare chair can actually be a chair that is in use and thus not "extra".

Let's look into Room 1J:

There are 10 chairs and and 10 students and all 10 chairs are occupied.

Someone knocks at the door and asks:

I wonder if there is a extra chair I could borrow.

Clearly not, as all ten chairs are in use. There are no leftover chairs.

But if the enquiry is

I wonder if there is a spare chair I could borrow.

Aha! this is different. The teacher can say:

Well as you can see, we don't have any extra chairs, as they're all in use. But I'm sure Johnny wouldn't mind standing up the rest of today and you can borrow his chair as long as you bring it back tomorrow.

This chair is a spare chair.

Note: One could argue that the chair that Johnny has vacated is now "extra," because it's no longer being used by Johnny, but actually it's still in regular use. In fact, Johnny had to put a chair deposit of $100 to reserve the chair for the semester, and he paid another $50 for an engraved name plate Johnny's Chair, which is attached to the chair. So, as far as the classroom goes, it's not really an extra chair. But it has become a spare chair that may be borrowed for the rest of the day.

To illustrate the difference between 'extra' and 'spare', let's ask a different question.

Let's go back into Room 5 (the one with 10 students, and with 15 chairs, stacked in the back that are collecting dust because no one ever uses them).

If you ask

How many extra chairs are there?

This means How many chairs not in use; that is, that are more than necessary and thus leftover do you have?

The teacher will answer 5.

If you ask

How many spare chairs are there?

The teacher might look quizzical and ask

How many do you need?

So an extra chair is a "leftover" chair, a chair not in regular use.

A spare chair is any chair that can be dispensed with–even if it's currently in use.

A last illustration:

A panhandler stands on a busy sidewalk and has his hand out and he says to passers-by:

Extra dollar?

His request is not that idiomatic.

If he says:

Spare dollar?

it's clear he's asking Dollar that you can dispense with?

Answer 6

From the Cambridge Academic Content Dictionary, American English:

extra

adjective, adverb [not gradable] US /ˈek·strə/

​added, ​additional, or more than ​expected:

Some ​students ​needed extra ​help. He’s been ​working an extra two ​hours a ​day. I ​bought some extra ​batteries.

And again from Cambridge Academic Content Dictionary, American English:

spare adjective (EXTRA)

[not gradable] not being used, or more than what is usually ​needed:

I ​keep my spare ​change in a ​jar.

So the word spare is a synonym for extra, but with slightly different usage and connotations. The word spare can also mean "thin" (a person with spare build) or "undecorated" (minimalist decor), either of which (strangely enough) implies the absence of extra things.

The British English definitions are worded rather differently, but the examples seem consistent with American usage.

My conclusion is that something that is spare (in the first sense) could generally be said to be extra, in that it is something additional beyond what is needed, but an extra thing might or might not be spare; it may be very much needed where it is. (Remember the students in the example under "extra"? They would not view the help they received as a "spare" thing.) That is, spare has a stronger connotation of "not really needed."

In your case, I think you could say either "spare" or "extra", but either word will emphasize different aspects of the event. If you say the student took a spare chair to another room, you are emphasizing the fact that the people in your classroom did not need the chair (although the other student apparently did need it). But you could also say it was an extra chair, referring either to the fact that you have more chairs than you really want in your room, or to the fact that the other student was going to add this chair to the ones already in the other room (where it would evidently be needed: extra, but not spare).