Prepositions of Time in English: BY, UNTIL, BY THE TIME, NO LATER THAN...


Hi, everybody.

Welcome back to

I'm Adam.

In today's video we're going to look at the prepositions: "by" and "until".

We're going to look at the differences between them, and how to use them, and what specific

meanings they each have.

We're also going to look at the expression: "by the time", as another way of using "by"

or whatever situation, and this one: "no ________ than".

Now, the reason why I left this blank is because you can actually put quite a few words in there.

We're going to look specifically at: "no later than" to replace "by" and "until", but for

now I want you to also understand that there's other uses for it, and I'll give you some

examples of those.

Now, before I start I will say Emma did a very good lesson about "by" and "until".

Mine is a little bit different because I'm going to show you some other situations where

you will use one or the other.


So we're going to start by figuring out: What's the difference between these two?

So look at our example sentences.

I'll get to our little time map in a second.

"I'll be at the office until noon.", "I'll be at the office by noon."

Now, first of all, let's assume the average workday is about...

Is from 9 until about 5 o'clock, but I have some...

I have some meetings in the afternoon so I will have to leave the office.

But if you want to meet with me, I'll be there until noon.

What does that mean?

It means that I will arrive at the office at the usual time, 9 o'clock, and I will stay there.

So my stay at the office will continue until noon.

At noon I will leave.

Okay? So this is when we're using "until".

Now, before I get in...

Into that again, let's look at the second one.

"I'll be at the office by noon."

So, here, we're looking at somewhere in this time, but not later than noon I will arrive

at the office.

Okay? Now, what's the key difference between these two?

Well, one, something continues.

An action starts, continues, and it ends at that time mentioned after "until".

So both of them have an end time.

You could even say a deadline, but that's for other uses.

There's an end time.

And that end time is noon.

Okay? Something will happen at noon.

Now, in the case of "by", it could happen before.

In the case of "until", only one thing will happen.

But the key to remember: When we use "by", we're looking at a finite action.

This arrive is a one-time thing. Right?

It'll... It can happen here, it could happen here, it could even happen here.

With "until" only here will I leave.


Now, what's the difference, another difference that we have to think about?

Is not only the continuance of an action and the finite situation of an action;

here, we're looking at something ending.

My time at the office will end.

Here, something can end or start.

So if you want to meet me, I'll be in the office by noon, so you can meet me

from noon until 5.

So the start time, the earliest time you can meet me is noon.

The latest time you can meet me is just before noon because I'm leaving at noon. Right?

So that's one thing to keep in mind.

The... Basically the implied situation.

Now: "I'll be at the office by noon and I'll stay until 5."

You can use both of them in one sentence.

Sometime in here I'll arrive, and then from 12 till 5, I'll be at the office.

So, what's the key?

Now I hope you basically notice this.

What's the key difference in these two sentences, is it the preposition?


Different prepositions, different meanings.

But what I hope you realize is that the difference is in the verb "be".


What does "be" mean here, and what does "be" mean here?

"Be... I'll be at the office until...

Until noon", means I will stay at the office until noon.

So this situation will continue.

Here, "be" means arrive.

"I will arrive at the office by noon."

So, one point here in this time...

Timeframe I guess you could call it, something will happen.

Continued, finite.

"Finite" means it's a one-time action and that's it, it's finished.

So that's a very important thing to remember with "by".


"By", and we also think about: "at", "on", or "before".

So, "at" for time.

This is a little review of prepositions.

"At 5 o'clock", "on Friday", "on day",

so: "At 5 o'clock or before.", "At noon or before.",

"On Friday or before."

Okay? "Until"...

Now, we don't use this preposition "to", but something continues to the end time.


So that's one way... Another way of thinking about these two in terms of: What's the difference?

"By" or "before" continue "to".


We're going to look at a few more samples, and you'll get a better idea of when to use

"by", when to use "until".

Okay, so let's look at some more examples and I want to come back to this idea of finite

actions. Okay?

"Finish" is a finite action.

Now, just to clarify, again: What does "finite" mean?

It means it's a very limited time.

It doesn't go on for a long time.

So if you're going to finish your homework, it means last question answered, done, finished.

You can't be finishing for a long time because the verb "finish" doesn't extend; it's done

or it's not done.


So: "I'll finish my homework until 5."

Now, a lot of people will say this, they will write this, but technically it's not correct.

"I'll finish my homework by 5." is okay because it's a one-time situation and it'll happen

at 5 or before, at some point in that time.

So, how would you fix the first sentence?

Two ways.

One: "I'll finish my homework at 5."

That's one way.

If you know you're going to be done at 5 you can say that.

But the better thing to do is to change the verb, make it a non-finite verb.

"I'll work on my homework until 5."

Means work, work, work, time goes on, work, work, work, time goes on, 5 o'clock, okay, I'm done.

Finished, not finished, not important.

If you finished, great.

If you didn't finish, that's fine.

5 o'clock is your end time, then you will finish later if you didn't finish by 5.


Now, another thing to keep in mind: We can use both prepositions with any tense.

You can talk about the past, you can talk about the future.

But when we're using perfect tenses, we use the "by" preposition.

Let's look at examples.

"I'll have completed my tasks by 5 o'clock."

"Will have completed", this is your future perfect.

The future perfect often makes use of "by".

Okay? We can also talk about the past perfect.

Now, here, I'm starting to introduce: "By the time".

"By the time" has the exact same use or the exact same function as "by", except that now

instead of saying: "By 5 o'clock", "By Tuesday", "By next year",

I'm giving you a more general time.

And then I'm identifying that time.


So I can be more generic...

General. I can say anything.

"By the time we're through", I don't have to give you a specific time, I can give you

a specific situation.

"By the time he arrived", so now the time is when this action happened.

What time of the day?

I don't know. Not important.

"By the time he arrived", so I have my adjective clause to identify the time, and then I have

my next clause: "She had already left."

So, because at this time he arrived...

"By this time" means at this time or before. Right?

So if it happened before, I must use the past perfect to show the relationship in time.


By the time he arrived, she had already left.

"I'll have completed my tasks by 5 o'clock."

So 5 o'clock, they're done.


Let's look at "until" just to show you there could be past, or present, future, etc.

"She waited in the lobby until he arrived."

So she waited, waited, waited, waited, waited.

Oh, there he is.

So, again, you don't have to use a specific time.

You can use an actual clause, and then there...

This is therefore a clause marker, an adverb clause marker, subordinate clause.

"Until he arrives, she..."

"She can", this is an "n".

"...she can wait in the lobby.

Until he arrives, she can..." so we have a present.

"Until he arrives," keep in mind this is still an adverb clause now we're looking at.

You can't use "by" as a clause marker, as an adverb clause, but you can use:

"By the time" with an adjective clause or "until" with an adverb clause.

"Until he arrives, she will wait in the lobby."

Present simple, future.

Again, think about when.

When he arrives, she will have been waiting in the thing for five hours.

You can also use the perfect with "until", but then you have to specify the time period.

When you're using perfect, go with the "by", more common.

Use "until" as an adverb clause conjunction.

That's another big difference between these two.

"By" always a preposition.

"Until" can be a preposition or a conjunction for an adverb clause, so that's important

to understand as well.

So now we're going to look at expressions that we can use to replace these in case we're

ever not sure.


Okay, so let's do a little bit of review before we look at some other expressions.

Before I want to do anything else, actually, I want to mention "until".

You might notice in many situations people using the word "till" or sometimes they'll

use like an abbreviation: "'til".

"Till" is a little more common, "'til" is a bit more common in American English.

Personally, there's only one letter difference, like one, two, three, four; one, two, three, four, five.

Just write "until".

If you're not sure, use "until" in your writing.

In spoken English: "till", "'til", both okay.

In written English go with "until".

Now, let's review this: "By the time".

We use "by the time" plus an adjective clause to identify which time.

So we can have two options.

I can say: "By the end of the lesson...", like let's say we're having a lesson now,

so: "By the end of this lesson, you will have learned about 'by', 'until'."

Or: "By the time"-which time?-"that we are done, you will have learned about 'by' and 'until'."

So, there are two ways to use "by".

The thing to remember is when you use: "By the time", make sure to identify which time.

If you have a specific time...

"End of the lesson" means this particular time when the lesson is finished, and then

go on with your next clause saying what will have happened then or before.

Maybe you already understand "by" and "until", in which case, good stuff.

Now, another thing I want to look at: "I'll be done by 7.",

"I'll be done no later than 7."

What's the difference in these two meanings?


We can use: "no later than" as a replacement for "by".

Now, why am I showing you this?

If you're ever in a situation where you're writing and you're not exactly sure if you

should use "by" or "until", and you don't want to make a mistake, maybe on a test or

whatever the situation, here's another option.

"No later than" means this is the absolute latest time, so this time or before.

It basically means the same thing as "by".


And again, I'm still using a finite verb in this case.

"When are you working until?"

So I'm asking: When is the...?

When are you ending your work?

"7 at the latest."

This is another expression, but be careful with it because some people say:

"Oh, I'm working until 7 at the latest.",

"Until 7" means 7 is the latest, so "at the latest"

becomes redundant.

If you're going to use this expression, don't use "until".

If you're going to use "until", don't use this added expression.

And: "I'll be there..."

Now, we can go the opposite way.

We can talk about earlier: "no earlier than".

So: "no later than" means end time; "no earlier than" means beginning time.

Do you remember that graph we looked at before when I said "by" could be an end or a start?

Well, that's where we have this.

The key to remember is that when we turn it around to use "by" or "until", then we're

going to basically go with the opposite verb, like negative or positive.

"I'll be there no earlier than noon.", "I won't be there by noon.",

"I won't be there until noon."

So "by noon" means noon or before I won't show up.

"I won't be there until noon."

At noon I will arrive and continue.


So the "won't be" will continue until noon.

The "won't be" will continue...

Will be from noon or before.

And again, different meaning to the verb "be", but you can use: "no earlier than", "no later than".

You can also use these.

These are basically minimizers and maximizers, this expression.

"No later than", maximum.

"No earlier than", minimum in terms of time.

You can use other expressions, you can use: "No sooner than", basically means the same

as earlier.

You can say: "No more than", means a maximum amount or a maximum number.

"No less than" or "no fewer than" means a minimum.

So, these are good to have for time, but just so you understand, they're applicable to basically

everything; numbers, quantities, time, situations, etc.

So, I hope that all of this helped you understand how to use "by", "until", "by the time", and

"no later than".

I hope you enjoyed this lesson.

Please subscribe to my YouTube channel if you did.

If you have any questions, please go to, join the forum and ask me the questions you have.

I'll be happy to try to answer them.

There's also...

There's also a quiz at

Take the quiz, make sure you understand which one of these expressions to use based on the context.

And, of course, come back again soon, see us again,

we'll have more great lessons for you, and I'll see ya then.


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