12am & 12pm – What’s the Difference?!

Owen Vickery

Learn about the difference between am & pm as well as other keywords for telling the time.

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) nor 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 keywords (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.

Written by Owen Vickery for EnglishClub.com

Owen Vickery moved to France upon graduation in the UK. In English teaching for 20 years & author of 2 books, he contributes to a site for learning English & specialises in writing online content.
© EnglishClub.com

43 comments

Kurt says:

Please avoid 12:00am and 12:00pm. It seems that if there is a consensus about what they mean in English, it is a rather recent one.

https://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noon_and_midnight
Joel Williams says:

You didn’t give a definitive answer. Your explanation of 8pm being in the evening made me think that 12pm was the end of the day, now I’ve missed the chance of a job application because I thought the deadline was the end of the day, thanks!
Debra Kadabra says:

There is absolutely no such thing as 12am or 12pm. It is either 12 noon or 12 midnight; or 1200 hrs and 2400 hrs. All other assumptions are blather.
Gary Kellum says:

We have a 24 hour day so use a 24 hour clock. I’m glad my $20 watch will show 12 hour or 24 hour time.
OhBloodyHell says:

You didn’t even answer the bloody question, FFS!
Gerrit de Nys says:

It’s too confusing, and I’m still not sure .
12am and 12pm are incorrect indications of time. It’s 12 noon and 12 midnight, period!……or use the 24 hour clock.
Alexi says:

Ask yourself this: when is 12:59 PM?

Is it one minute before 1 o’clock in the afternoon or 1 minute before 1 in the morning?

PM Means post meridian – after midday – so 12:59 PM is one minute before 1 o’clock in the afternoon, therefore 12:00 PM is midday.

It seems odd, and it is because 12:00AM and 12:00PM never existed before digital clocks, everyone used to say midnight and midday. To save all confusion, use the 24 hour clock or just say noon or midday.
Paul Jansma says:

I was an airline pilot for 41 years. In aviation We always used the 24hr clock. 0001 being AM or 1 minute past midnight and 2359 being PM or 1 minute before midnight.
Personally when people use 12am or 12pm I have always said to myself consider am = at morning and pm = past morning. So 12am to me = 12 midday. 12pm to me = midnight.
Easier than am = ante meridiem (between midnight and midday) and pm = post meridiem(between midday and midnight.) Hope this helps?
Jerry Feather says:

It seems to me that there are two 12 hour segment in the day. One of them start at zero and ends at noon, 1200 o’clock, and the other one starts at zero, and noon, and ends at 1200 o’clock midnight. The first one ending at 1200 o’clock should be AM and the other one ending at 1200 midnight should be PM, if at all. Actually there is no am or pm. it is just 12 noon or 12 midnight.
John says:

Just use 00:00 and 12:00, then it does not matter, whether it is am or pm
Mikhail Volkov says:

Owen, great article except for one slight error. In the section titled “12-hour clock or 24-hour clock?”, you make the following statement: “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 ?”
If referencing any time using the 24-hour clock, the colon ( : ) is not used. All times are written and spoken in the hundreds. 2pm would be 1400 (spoken as “Fourteen Hundred”). 1am is 0100 (spoken as “Oh One Hundred”).
Otherwise, I agree with your assessment of which is considered to be 12am and 12pm. Thanks for the thorough explanation.
Graeme says:

Noon is 12:00PM. Some think it is 12:00AM, but it isn’t, that’s midnight. PM means post meridiem (after noon) and AM means before noon, so there is confusion as to what noon is, but there is no confusion that the hour after noon is PM, so 12:01-12:59 is PM, post meridiem, after the sun has passed the meridian.

So, if 12:01-12:59 in the afternoon is 12:01-12:59PM, is noon 12:00AM or PM? You can take your pick as it is not before noon or after noon, it is noon. But it makes more sense for it to be 12:00PM as time going 12:00AM, then 12:01PM, 12:02PM makes no sense. Take a look at your favorite airline and book a flight at midday, book an appointment in Outlook or Google calendar, you’ll see they all use 12:00PM for midday.

https://www.timewatch.com/blog/am-pm/
francis says:

what is next to 11:59 AM? ANS. 12:00 PM
Reinante m.delapaz says:

Better to use 12noon or 12midnight,, to clarify the time,,,instead 12am or 12pm,,that’s all.
Timplex says:

So I gather that from 10:59 pm, we can get to 11:59 pm by passing one hour, but if we pass one more minute, to get to 12:00 pm we need to go backwards 12 hours, since going forward one minute will take us to 12:00 am. And that is the start of a new day.
Language is as much an art as a science.
Charles Haroun says:

It’s good knowledge and thanks alot!!
Charo Paredes says:

Meridiem means noon (from the Latin meaning “half the day”). Thus a.m. means before noon (ante meridiem) and p.m. means after noon (post meridiem). So 12 can never be either a.m. or p.m.
Valerie says:

My husband of 47 years and I were arguing about exactly this topic earlier in the day. Joe’s response (at Sheldon Li) is right on the mark,and also supports my arguement!
Valerie says:

My husband of 47 years and I were arguing about exactly this topic earlier in the day. Joe’s response is right on the mark (and also supports my arguement)!
Erik says:

Rubbish most of it:-)
what comes after 11.59.59?
00.00.00!
Therefore midnight is 12 am – period.
Henry says:

Noon actually should be designated 12 M, or 12 meridiem.
Patrick says:

A minute before midday is 11.59am
Naturally what should follow is 12.00am
One m8nute later is 00.01pm.
How do you go from 12pm to 00.01pm
Is it meant to confuse?
I would say that midday is 12.00am because a minute earlier is 11.59am.
john says:

use 12hr clock when talking .. cause more words after questions dont kill .. but use 24hr in any writing .. easy
John says:

When I was a lad (1940s), my teachers made it all very clear. “Noon” and “midnight” were used without any reference to the number 12.
12”am” and 12”pm” are each patent nonsense, since the moment of reaching each meridian is of infinitesimal time -passed as soon as it is reached.
The “Sunday midnight” ambiguity just has to be clarified by the context in which it is used.’
Mike F says:

Our 12 hour clock convention splits the day into two 12 hour periods called am followed by pm. We should stop calling 1 minute after midnight 12:01 am as 12 hours of that new day have not yet passed, that time should be called 0:1 am or zero 1 am, 50 minutes later would be 0:51 am and 60 minutes after midnight would be 1 am, ie drop the 12 and call it 0/zero.

As a consequence 11 hours and 59 minutes after midnight would be 11:59 am and 1 minute later we would have both 12 am, (11+1) and also 0 pm or zero pm as it is the end of am and the start of the pm period, doesn’t matter which you use, it is clearly midday and the same point in time.

50 mins after midday would be 0:50pm or zero 50 pm, can’t be 12:50 pm as we haven’t even passed the first pm hour, 1:00 pm, yet. 11 hours and 59 mins after midday would be 11:59 pm. 12 hours after midday would be 12 pm and also 0 am, once again it’s the end of pm and the start of am, both conventions are correct at the point of midnight.

Saying that 15 minutes after midnight is 12:15 am implies that 12 hours and 15 minutes have already passed in that day, clearly it’s wrong, the 12 from the previous days pm period cannot possibly be included in the following day, our number system starts at 0 not 12 and as there are 60 minutes per hour, 15 minutes past midnight is 00:15 am or zero 15 am.

All that’s required to clear up the 12 am, 12 pm misunderstanding is to accept that 12 am follows 11 am to become midday which in reality is also 0 pm and 12 pm follows 11 pm to become midnight. This follows the 24 hour clock convention split into am and pm and means midnight is always the end of a day. Therefore meeting someone at midnight or 12 pm Monday is the last moment in time on Monday equal to the junction in time between Monday and Tuesday and not the junction of Sunday/Monday.

The use of 12 instead of 0/zero at the beginning of the am and pm periods is completely wrong and confusing. Both digital and analogue timepieces indicate precisely that convention, any time between the 12 and 1 on the timepiece is less than 1 approaching 1.
John O'Brien says:

We say 12 at midday or midnight as a continuation of the sequence from 1 up to 11, and 12 comes after 11.
Hence, if we refer to the mornings and say 1 am to 11 am, then 12 must follow as 12 am (midday); and, if we refer to the afternoons and nights and say 1 pm to 11 pm, then 12 must follow as 12 pm (midnight). Think of it as simple counting.
Nsebid says:

This is confusing to me as well, but i think the 24 hour clock clears out the confusion
Owen says:

Thank you for all your comments. It is indeed a complicated question.
As Andrea says: “Better say “12 noon” or “12 midnight”, or else use the 24-hour clock (as airlines do).”
12pm is midday (or noon).
12am is midnight.
Midnight on Sunday is during the night between Sunday and Monday, as Joe says.
5 past midnight would either be 12:05am (in the 12-hour clock) or 00:05 (in the 24-hour clock) NOT 25:05. With the 24-hour clock, we start again from 00:00 after 23:59:59.
As the question can be so confusing it’s better to:
a) Use the 24-hour clock (00:00 for midnight – midnight on Sunday is at the end of Sunday). The 24-hour clock is generally used in aviation, the transport industry… Or
b) Use the 12-hour clock BUT say 12 lunchtime (or 12 noon) for the 12 o’clock during daylight hours and 12 midnight for the 12 o’clock during the night.
Yash says:

I think 12:00 “AM” should be noon after 12:00:01 should start with “PM”. Like wise 12:00 “PM” should be midnight after 00:00.01 (12:00:01) should start with “AM”!!!

For example after 24:00 we do have 24:01; 24:02 ….. so on till 24:59 when it is 24:60 which is 25:00 but we don’t say 25:00 but we say it 1:00 “AM”. Therefore from 24:00 to 24:59 should be “PM” not AM. Same way after 12:00 noon i.e. 12:00:01 to 12:59 should be “AM” not PM. otherwise one hour will be vanished in between. What do you think Mr. Author?
Jasper K. says:

I agree with others who reason that 12 AM is midnight, as 12:01 AM is one minute past midnight. Just as 12:00:01 AM is one second past midnight.
julia says:

12 AM is midnight from the logic that it would be hour cero (0) or 00:00 hours, because 0 o’clock comes before 1 o’clock, and it is the start of the new day, and AM, since its midnight-noon or morning hours.

So 12 o’clock midnight is equivalent to 00:00 hour.
12:00 pm is noon because the day is not over yet, and the laps of noon-midnight starts which means it’s afternoon.

The 24 hour clock makes this more obvious and clear.
in the 24 hour clock midnight is hour cero or 00:00, and noon still remains 12:00.
Andrea says:

@ r j cedar
I think the article DOES answer the initial question: ie 12am and 12pm are meaningless, they have no meaning and should be avoided. Better say “12 noon” or “12 midnight”, or else use the 24-hour clock (as airlines do).
r j cedar says:

This article did NOT answer the initial question:

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?

My covid 19 shot is at March 23 at 12PM, logically that is 12 noon, but this is not a question of logic, but of time standards. Rather than saying “There is some debate about this” this article should say what the protocol actually is.
bill says:

How to explain ” we will deliver your parcel between 10am and 12pm”……a time frame of 2 hours or 12?.
Jack says:

Thank you for your sharing。It’s very useful for me to understand the meaning of the PM&AM。
Using 24-hour method can revolve our confused about “the midnight on sunday”.
Joe says:

@sheldon Li
Yes, you might wonder: “Is it midnight at the start of Sunday or at the end of Sunday?” BUT, look at the word “midNIGHT”. Midnight is in the MIDdle of the NIGHT, not in the MIDdle of the DAY! Sunday NIGHT runs from 6pm (Sunday evening) to 6am (Monday morning). So “midnight on Sunday” is at the end of Sunday, not at the start. Check out Day and Night:
https://www.englishclub.com/vocabulary/time-day-night.htm
Owen says:

@sheldon Li
That’s a very good point! Midnight on Sunday is confusing.
Formal documents (contracts, agreements…) may well clarify by saying something like 23:59 or 00:01 to get around this question.
We can also say “midnight Sunday morning” or “midnight Sunday night” to clarify.
sheldon Li says:

Thank you but I am more confused after reading this article because I still don’t know how to understand “the midnight on sunday”.
David Martín says:

@Uni you’re an early bird 😉

It’s 9:43am in Spain.
Uni says:

I commented at 5:27 in the morning.
Bijan says:

Thank you so much.
Αpostolos says:

Good morning
Thanks.Very useful explanation
Hamza Haji Abagidi says:

Thank you very much for goodgiving us this good explanation for the difference.