The problem of confusion arises when
Example:
“At 12 a.m. Friday, thousands of bills in the Texas House of Representatives will meet their end.”
Is 12 a.m. early morning at nighttime at the beginning of the day Friday, and 12 p.m. is the end of day Friday also at nighttime.
or
Is it better to always leave off the words noon and midnight and just put a.m. or p.m. when in combination of the day of the week.
“12 a.m., Friday, means night time.
and
12 p.m., Friday also means night time but not it does not mean “midnight.”
So leave out the words midnight and noon because they only confuse the reader.
There should be a “style guide” telling how dates and times are to be formatted in print at journal and magazines and for formatting rules regarding how to submit an electronic file of typed text such as submitting a whole book to Amazon for publication on their Kindle electronic books site.
Actual noon (meridian) is an infinitely small point or dividing line in time, not a time per se, so, functionally, as soon as the clock changes from 11:59 am to 12:00 pm it’s already afternoon (post meridian). Personally, I think it would be more logical to use 0 instead of 12 for both noon and midnight, but I guess there’s no point in fighting established convention.
I would like to elaborate on my earlier explanation.
This debate arises from a logical contradiction, not a grammatical one.
Times within the sets of both pm and am are defined by their relation to a single time, that is, noon.
Neither qualifier (“ante” or “post”) can dominate the other’s validity in argument. Those who argue in favour of this way or that, for noon to be pm or am, by using the terms am and pm themselves, are subject to their arguments being mirrored with equal strength in counter-argument by the opposite interpretation.
By using the definitions am and pm for a set, we automatically exclude the time of noon itself into either set, or, we must concede noon is in both sets and therefore the description am or pm is valueless when applied to noon itself.
The issue could be solved by replacing the terms am and pm themselves, with for example, “after midnight” and “after noon” which would clear things up by using two distinct starting points upon which to hang the categorisation. All time would be in one or the other.
The meaning of post meridiem “pm” is “after” or “subsequent” to midday.
The meaning of “am” is ante or before midday.
12 noon (midday) is not subsequent to noon, rather, it is at noon itself and it exists prior to all times labeled “post noon” or pm. It is logically absurd to define something as a member something of a set of things that exists only after itself.
Therefore 12pm (12 after noon) is not noon.
Similarly, noon cannot be described as being a time subject to the requisite of it being before itself.
Therefore 12am (12 before noon) is not noon.
You cannot include an object into a set set of objects that are subject to a requisite definition (label) that exclude it.
Round pegs don’t fit into square holes and vice versa.
Ingenious, Kathy.
The advantage of the present system is that once you understand it, it also reminds you that midnight is already the next day, e.g. the date changing in one minute from 23:59/ 11:59 pm on the night of 13 February to 00:00/ 12 am/ midnight on (theoretically) the morning of 14 Feb.
@Kathy A.
Great idea!
Why don’t we use just the first letter:
a = a.m., or morning
n = noon on the hour
p = p.m., or
afternoon/evening
m = midnight on the hour
SO much simpler.
TRY THIS FOR TIME:
YEAR–2025
MONTH–02
DAY–03
HOUR–01
MIN—58
SEC—15
= 20250203015815 NO DOUBTS
This discussion is about English language convention. I was taught the time ( incorrectly ) that AM meant morning and PM meant afternoon. To me 12:59 pm is a continuation of the night time measurement following on from 11pm , while 12:59am is day time measurement following on from 11am.
Because we are using Latin in English we have this confusion.
I.e. 12:15 (or 12:59) AM or PM is confusing and if we were to adopt a more scientific convention we would just say for 00:15 “15 Minutes AM” ( no need to express the Zero hours ) for the early ‘morning’ time or “15 Minutes PM” for the afternoon time. At 1 we can revert to the accepted meaning of AM and PM.
Perhaps I’ll start doing this. Also, I frequently use 24 hour time, for recording sign in and out working times and filling out time sheets, it is easier to calculate worked hours.
BTW: on Monday is next Tuesday tomorrow (this Tuesday) or Tuesday in the following week (or is that Tuesday-week)?
00:15 is quarter (or fifteen minutes) past midnight.
11am is the morning and the 12 that follows it might seem to logically also belong to “am” as some have commented.
But this 12 is mid-day and if this is the “meridiem” then time after it is “post meridiem” as the author states.
Therefore counter-intuitively 12 noon has to be pm, not am.
24hr clock is better but not always available.
Per NIST – US national institute of standards and technology, “This is a tricky question because 12 a.m. and 12 p.m. are ambiguous and should not be used.
To illustrate this, consider that “a.m.” and “p.m.” are abbreviations for “ante meridiem” and “post meridiem,” which mean “before noon” and “after noon,” respectively. Since noon is neither before noon nor after noon, a designation of either a.m. or p.m. is incorrect. Also, midnight is both twelve hours before noon and twelve hours after noon.”
The same as a logical argument stating, time > 12 or time < 12. This does not ever mean time is = 12 on any planet!
Prior military and using 2400, 1-2-3-4-5-6-7-8-9-10-11-12. These numbers follow in sequence, which I think all will agree. What type of logic would have 1-11 as am and then make any logical argument that 12:00 is PM in this 12 hour period??? 12:00:01 is where PM would start, 24:00 is where the days ends, and the next day starts at 00:00:01.
A day ends at 24:00 and new day starts a zeptosecond after that time, and the reason clocks display 12AM at midnight and 12pm at noon. You don't get to witness true 12:00:00 and 24:00:00 but for a zeptosecond, which is a trillionth of a billionth of a second.
https://www.nist.gov/pml/time-and-frequency-division/times-day-faqs
Parallel confusion, but to me I think it’s better to agree mostly on 24 hour system which is 00 00.
I have to correct my previous comment. 24 hour time does not go beyond 2359 as Yash noted in his comment. I took his word for it and I shouldn’t have. It didn’t sound right at the time and I quickly realized he wasn’t.
So, after 2359 hours comes 00:00 hours (I know the colon isn’t used). I’m curious how to say 00:15.
I think “0” should be “zero”, not “oh”. Is it zero fifteen, zero hour 15, zero zero 15?
If 1500 is “fifteen hundred”, what is 0015?
All of this is very confusing. I was wondering what happened using 24 hour time after 2400. Someone mentioned it goes to 2401 and then reaches 2459 which is 59 minutes after midnight. But that is also the next day. So, 2459 on Sunday is technically Monday morning – not Sunday at all.
I think the first hour should be zero hour.
Side note – 0 = zero. 0 is not “oh”. “Oh” is a letter not a number.
So, 5 minutes after midnight would be zero 5 hour. 5am would be zero 500 hour.
But our time is not measured by hundreds so why say zero five hundred?
Conclusion = there is no right answer.
I believe 12am and 12 pm are the same time. How so?
Well am means ante meridiem, pm means post meridiem and meridiem is midday.
Hence 12am is 12 hours before the meridiem ( midday ) and 12pm is 12 hours after the meridiem (midday).
Thus 12 am and 12 pm are the same time which is midnight.
However, having said that, the convention we use is 12am is midnight and 12pm is non or midday.
Therefore to avoid all the confusion it is best to use the 24 hour clock, where 00:00 is midnight at the start of the day and 12:00 is middle of the day or midday.
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
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!
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.
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.
You didn’t even answer the bloody question, FFS!
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.
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.
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?
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.
Just use 00:00 and 12:00, then it does not matter, whether it is am or pm
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.
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.
what is next to 11:59 AM? ANS. 12:00 PM
Better to use 12noon or 12midnight,, to clarify the time,,,instead 12am or 12pm,,that’s all.
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.
It’s good knowledge and thanks alot!!
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.
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!
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)!
Rubbish most of it:-)
what comes after 11.59.59?
00.00.00!
Therefore midnight is 12 am – period.
Noon actually should be designated 12 M, or 12 meridiem.
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.
use 12hr clock when talking .. cause more words after questions dont kill .. but use 24hr in any writing .. easy
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.’
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.
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.
This is confusing to me as well, but i think the 24 hour clock clears out the confusion
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.
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?
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.
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.
@ 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).
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.
How to explain ” we will deliver your parcel between 10am and 12pm”……a time frame of 2 hours or 12?.
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”.
@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
@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.
Thank you but I am more confused after reading this article because I still don’t know how to understand “the midnight on sunday”.
@Uni you’re an early bird ;)
It’s 9:43am in Spain.
I commented at 5:27 in the morning.
Thank you so much.
Good morning
Thanks.Very useful explanation
Thank you very much for goodgiving us this good explanation for the difference.
