# Is "until" inclusive or exclusive?

I sent an email to someone and got an auto-reply saying:

I am out of the office until 09/15/2014.

Does this mean he will be available on the morning of the 15th?

• I am out of the office until 09/15/2014.

My question is, will he be available on the morning of the 15th?

Well, pragmatically, if that date lands on a Monday, then I'd think he would be in his office that day.

Let's see how the word "until" kinda works. For example, consider:

• 1) "[The man kept on kicking the bear] until the bear growled."

That means that when the bear growled, the man immediately stopped doing whatever action he was doing (such as kicking the bear). That is, if I were that man, I'd stop kicking the bear--but then, I wouldn't be kicking a bear to begin with.

So let's now tweak that so it's somewhat more similar to your example:

• 2) "[The man kept on kicking the bear] until 09/15/2014."

That means that when it became 09/15/2014, the man stopped kicking the bear. (Poor bear.)

So, now, with your original version:

• "I am out of the office until 09/15/2014."

That means that when it becomes 09/15/2014, the man will stop being out of his office -- which implies that he will be in his office (right then and there on that given date). And if he is normally at work in the mornings, then he probably oughta be there that morning--but who knows, maybe he'll be busy catching up with his emails and whatnots.

OH! LOOK! 09/15/2014 is a Monday!

Phew! It looks like my rationale is rational. Surprise, surprise. Sometimes it works out that way. (And sometimes it don't.)

tl; dr - It's exclusive if the situation described is notable by its absence. It's likely to be inclusive if the situation described is notable by its presence.

At its heart, until describes when the transition happens. If you say "X until [time]", you mean that X becomes not-X on [time].

The problem comes, as you note, when [time] is a span of time (like a whole day) rather than an instantaneous moment.

# Absence = almost certainly Exclusive

Let's look at an example like yours:

I'll be out of the office until 9/22.

The situation we're describing is being out of the office. The relevant fact is absence, that I am normally in the office, but during this period I am not.

On 9/22, you can expect that I will be in my office.

A few other examples where the state is notable by its absence or negation:

There will be no coffee until 9/22. (On 9/22, there will be coffee.)

I won't be running the morning meeting until 9/22. (On 9/22, I will be running the morning meeting.)

## Presence = likely Inclusive

Now let's look at the opposite situation:

I'll be in Toronto until 9/22.

The situation we're describing is being in Toronto. This state is notable by its presence. Being in Toronto is what we're considering noteworthy in this example, rather than not being in Toronto.

However, the correlation here is not as strong. A statement of presence is likely to use an inclusive until, but not necessarily.

On 9/22, I will probably still be Toronto, or I'll be on my way back (but I might mean that I'll be back already on 9/22).

A few other examples where the state is notable by its presence:

I'll be on vacation until 9/22. (On 9/22, I will be on vacation. Probably.)

We'll have rain until 9/22. (On 9/22, it will be raining. Probably.)

I'll be in the hospital until 9/22. (On 9/22, I will be in the hospital. Probably.)

• I would say that a statement that someone will be absent until 9/22 would that the person cannot be expected to return before the beginning of that day, but will likely return before the end of that day. The term "through" implies an extension to the end of an interval. Someone who is gone through 9/22 would be unavailable until the next business day; a service that is available through 9/26 will be available until the end of that business day. Commented Sep 13, 2014 at 20:34
• @supercat, through is a whole nother can of worms.
– Joe
Commented Sep 13, 2014 at 23:17
• @Joe What does `tl; dr` mean in the beginning of your answer? Commented Sep 15, 2014 at 6:27
• @AwQiruiGuo, it's internet slang for "too long; didn't read". It's used to introduce a short version, ostensibly for those who wouldn't bother reading the rest.
– Joe
Commented Sep 15, 2014 at 9:55
• "I'll be on vacation" sounds almost synonymous with "I'll be out of office" and it doesn't sound very intuitive that it is a statement of presence, unless it is intended for someone who's already at the destination of the speaker for the vacation. Commented Dec 20, 2017 at 4:46

I think most folk I know would understand that he is back in the office when the condition implied by "until" is met. So he will be there on the 15th.

It may also help to consider the statement "... until the day after 09/15/2014". I think we would all expect him there on the 16th, and would be very surprised to find him not back until the 17th.

This message does not say whether he will be in the office on the 15th, let alone the morning of the 15th. When I write out of office e-mails, I try to say when I will be out of the office, and when I will return. For example:

I will be out of the office Monday September 8 through Friday September 12, 2014, returning the afternoon of Monday September 15, 2014.

• yes it does say that when he wont be in office. And the message has no other information, so it might be assumed that he will be available once those days he mentioned he wont be available are gone. Commented Sep 13, 2014 at 4:14
• @Man_From_India -- This is a classic off-by-one problem. Some people use "out of the office until 9/15/2014" to mean on vacation through the 15th, whereas other people use it to mean "returning on the 15th". Commented Sep 13, 2014 at 4:19

TL DR: When strict logic is applied I perceive till as inclusive, until as exclusive,

TL DR: In real world there are so many ways of understanding this (as you can see in other posts here) - on writer's understanding, and yours = you should ask to be 100% sure.

TL DR: In any case, I would insist on strict logic understanding as it is non-ambiguous. But a real world is a real world...

Explanation: Strictly logically, when the calendar turns 09/15/2014, means it is 09/15/2014 morning 00hrs 00min, the 00th second of 15th September is runnig, it is yet 15th September, so this person should be in the office.

In the real world, as the business hours start at 8:00AM, some people perceive this as a point in time when they will be available, no sooner. The problem is that it is not explicitly written, said, and thus ambiguous. So we have no other chance as to ask.

Lessons learned for me: we should specify the target time more exactly if applicable, e.g. in Hrs:Min format, to be clear, avoid misunderstanding = spare the time and resources, not looping in question-answer clarifications of what was the note's meaning. Otherwise the 00:00:00 morning time would be understood as the moment when the situation status changes.

P.S.: The strict logic version could be also a solution for the "timespan vs. point in time" and "presence vs. absence" problems described in other posts here. Computer programming logic (Do-Until loop) as well uses such strict specification (must be binary, non-ambiguous, exact, strict). I am not an English native speaker, sorry for my poor lang. - the logic explanation was the goal. Correct, what is wrong pls.

Till/until some day can be both inclusive and exclusive. Until is defined as "up to the point in time or the event mentioned", but a day is not a point in time, rather it's an interval of 24 hours.

In most cases it can be implied from the context:

We are open Monday till Friday.

Most people will include Friday, i.e. on Friday they are still open. To understand why simply add the time (assuming most firms are open at 8am and close at 6pm):

We are open Monday till Friday, 6pm.

If they wanted to exclude Friday they would be open "till Thursday, 6pm".

We are closed till Monday.

Most people will exclude Monday, i.e. on Monday they are already open, because:

We are closed till Monday, 8am.

If they wanted to include Monday, they would be closed "till Tuesday, 8am".

I am out of the office until 09/15/2014.

He is probably out of the office until 09/15/2014, 8am, so on 09/15/2014 he will be already in the office.

In situations where the ambiguity cannot be resolved from the context it's better to specify the time or say whether the day should be included or excluded. If, for example, a firm is open 24 hours a day 5 days a week they would say:

We are open Monday 12am till Saturday 12am.

or

We are open Monday till Friday, inclusive.

If you someone tells me I need to borrow some money till september 15, 2020, believe me on the 15th of that date I will be expecting to get the money on that day so same applies for I'll be out the office till september 15, 2014, that person will be back on the 15 of that day.

• Why do you say your first statement is true? Why does it imply the truth of your second statement? You didn't answer Does this mean he will be available on the morning of the 15th? Commented Apr 10, 2020 at 1:01