# How can I intuitively know that the "in" in "in 3 days" means "after"?

I learn from answers of this and this question that:

"in 3 days" implies after 3 days or approximately after 3 days.

It seems very counterintuitive, to a Chinese at least. How can I intuit that the "in" in "in 3 days", which seems equivalent to "*_day"(indicating "first_day" or "second_day" or "third_day") in ["first_day", "second_day", "third_day"], means (approximately) "not in"(precisely "after") that set?

This question may seem naive and trivial to most of the native speakers, but maybe someone(especially those kids who are learning English as a foreign language like me years ago) also wants to raise this kind of questions.

• To clarify what you are asking: is your question about, whether 'in 3 days' said on Sunday means Wednesday or Thursday? Or is it about something else? Commented Mar 20, 2018 at 10:09
• Without context you can't. Is the statement "x will happen in 3 days" or "y can be done in 3 days"? Commented Mar 20, 2018 at 10:29
• @charmer In this question I mean the case of "x will happen in 3 days". Commented Mar 20, 2018 at 10:43
• In which case I'd expect x to happen at approx 3 days from the statement being made, However it may also partly depend on when in the day this is said. Said late on Sunday, I could assume late Wednesday - but not be surprised if early Thursday is when 'x' happens (don't count Sunday). Said early on Sunday morning I might assume to count Sunday in the three days and expect end of day Tuesday or Wednesday morning. Without someone stating an exact day and time, it's open to some flexibility on meaning and interpretation. Commented Mar 20, 2018 at 11:04
• On re-reading, I see @laugh has actually made my point, .. :) Commented Mar 21, 2018 at 0:31

"in 3 days" implies after 3 days or approximately after 3 days

... is not true in general. "In" is a proposition that usually implies something being included (in a place, time, group, etc.). "In 3 days" intuitively means something like "within a period of 3 days" to English speakers. But there are subtleties...

The context may fix this period to start from the present time, and the event may be a single instant within the time, but it's not always the case. For example: "this car goes from 0 to 55 in 10 seconds'. It is a general statement (not from now), and it takes the whole 10 seconds.

How much context is needed depends on the case. If the context does not clarify what "in" means, then the meaning may be ambiguous. Natural languages do not rule out ambiguity! If you hear an ambiguous statement you may ask for clarification. If you make one, you will likely be asked for clarification.

You can use other prepositions like "within", "after", "during", "by" etc. to reduce ambiguity.

As a native speaker, this is interesting - a use of in I didn't even think about until now.

3 days is a limit. You are going to do something before that limit expires. Therefore you are doing something in the limit.

The fact that you won't do anything on day 1 or 2 is implied.

If you want to make it clear you mean that you can call on day 1 or 2, within would be used.

The bad news is that prepositions are idiosyncratic, and their uses cannot be intuited confidently. Like irregular verbs or spelling, they are learned through practice and exposure, further complicated because their usage differs slightly by locale (e,g, New York, standing on line vs. in line in the rest of the U.S.) and also shifts over time.

They do not translate, either. In French you would also say, for instance, en deux jours, but en cannot be directly translated as in; French employs en where English uses like, at, or by. Similarly, English by is not equivalent to German bei, as some English by expressions would use von or mit in German, and some bei uses are expressed using at or with in English.

As your second linked question notes, the intended meaning of in 3 days would depend on context, and you would use additional modifiers or express the idea differently if you needed to be more precise. The inspector is coming in the next three days, for instance, means the inspector should be expected at any time between now and three days from now, whereas The inspector is coming in three days at the earliest of course means just the opposite, that the inspector should not be expected until at least three days from now.

• The von or mit cases can usually be rendered as with in English, so that's not really a point at all. The issue is more that where we used to say in time to mean during [this|that] time, it's warped a little to sometimes mean after [this|that] time. I realise of course that the French might say pendant que ... Commented Mar 21, 2018 at 0:34
• … but the point stands that doing [X] in three days can be “intuited” to some degree to mean during the next three days [someone will be] doing [X], and it will be finished [hopefully] after those three days. Commented Mar 21, 2018 at 0:38
• @WillCrawford The point is that prepositions do not correspond across languages. Even a single example of an expression employing a different preposition (or a different construction altogether) from a frequently corresponding preposition in another language makes the point; I was just trying to think of examples off the top of my head, and my German is less terrible than my French. Commented Mar 21, 2018 at 0:45
• Fair enough. I know that pain (I get utterly stuck with some prepositions, and I find German difficult just because most of them sound completely different, ... but bei/mit/von are the few I remember! :o)) Commented Mar 21, 2018 at 0:49