12 o’clock: we all know there are two a day – one at lunchtime and one at night – but which one is 12am and which one is 12pm?
That’s what we’ll be looking at in this article. We will also see some other useful words and phrases that can crop up when we need to tell the time or ask what the time is.
So what is am & pm?
First of all, what do am and pm actually mean? Both come from Latin originally:
am = ante meridiem (between midnight and midday)
pm = post meridiem (between midday and midnight)
So returning to the question about the difference between 8am and 8pm:
8am is in the morning, and
8pm is in the evening.
OK, but what if someone talks about something happening at midnight on Tuesday? Is that 12am or 12pm. Is it the night between Monday and Tuesday or between Tuesday and Wednesday ?
Midnight and midday
Some will say midnight is 12am, and therefore that midday (or noon) is 12pm. Others will say this doesn’t make sense as noon can be neither am (before noon) or pm (after noon)!
When we talk about midnight last night or midnight tonight, the meaning is clear ; but less so when we talk about, for example, midnight on Sunday. Is that at the beginning or at the end of Sunday?!
There is some debate about this so it’s better to be clear from the outset, for example:
I should be home by midnight Saturday night.
The last bus arrives just before midnight on Friday nights.
12-hour clock or 24-hour clock?
In English, do we use the 12-hour clock or 24-hour clock ? In other words, do we say for example 2pm or 14:00 ?
In general conversations and situations in English, we use the 12-hour clock format. In practice, that means counting the hours from 1 to 12 in the morning and in the afternoon. More often than not, it’s clear if we are talking about the morning or the afternoon. Let’s look at a few examples:
I usually have breakfast at about 6:30 – we have breakfast in the morning.
We’ve got a team meeting at 2:15 – a team meeting implies a work situation, people do work shifts but we can be reasonably sure it’s in the afternoon.
The film starts at 7:45 – films are usually shown in the afternoons and evenings so it’s 7:45pm.
Sometimes, such sentences can be unclear :
His plane leaves at 8:15.
Is that am or pm ? Planes leave at both those times. It’s clearer to say something like :
His plane leaves at 8:15 tomorrow morning.
They’ll be arriving at about 7:30 Friday evening.
Some other key vocabulary
To finish, here are some key words (highlighted in bold) that can be useful when telling the time, some of which we’ve already seen :
I eat in the morning / afternoon / evening.
They sleep at night.
We arrived just before / just after 8 o’clock.
What time is it ? It’s almost 10 o’clock.
I should arrive at about / around 7:30.