There are several known ways to talk and write about time. We can use seconds, minutes, hours, and even days to measure time.
When we work locally, we barely need to think about time zone differences.
At other times, though, we need to be extra cautious with time differences because our colleagues live in other parts of the world.
The second situation above has led many people to ask curious questions about how to punctuate time zones correctly – especially with a pre-comma.
So, today, we’ll look into how we can tick this concern off of our list. Let’s begin with a quick answer.
When does a comma come before a time zone?
A comma comes before a time zone when it is used after a clock time and a date and spelled out as well as when it comes after an introductory or a parenthetical expression. No comma should come when the abbreviated time zone comes after the clock time and when it is a restricted part of a sentence.
A comma comes before a time zone when…
Deciding when to use a comma before a time zone is something that requires a bit of attention; it can either be too easy or too tricky for some people.
Those who regularly need to refer to different time zones and use them in writing may find this thing mundane.
However, those who do not engage quite a lot in communicating with people across the globe may think otherwise.
To be fair, learning and knowing all the rules on appropriate comma placement is not for everyone because it is something that only gets better with constant practice.
So, if you are not all too familiar with how commas work, perhaps reading our comma cheat sheet could make your life a little less taxing.
Using commas with entities like dates, clock time, and time zones may come off as a bit intimidating. But, at the end of the day, the real purpose of doing so boils down to sense-making.
Without commas, sentences get cluttered and are hard to understand. So, no matter how uncertain the “rules” are at times, we still need to learn them.
When writing time zones within sentences, there are a few things that we need to bear in mind regarding pre-comma placement.
These are as follows:
The time zone is spelled out and comes with a clock time
When the time zone is spelled out or not abbreviated, it is treated as a regular noun phrase when used within a sentence.
From this, we can understand that the typical comma placement rules used in regular sentence formats also apply.
The sticky part comes when a time zone is used together with a clock time – this is probably what’s causing the confusion among many people.
We typically write the clock time before the time zone, such as when we say “2:00 p.m., Pacific Standard Time” or “2:00 p.m. PST.”
However, we have to note that the comma is only used before the time zone, which is “Pacific Standard Time” in our example, when it is spelled out completely and not abbreviated.
Also note that the word “Pacific” is a proper noun. This means that its first letter needs to be written in uppercase all the time.
Meanwhile, the phrase “standard time” is a common noun and hence, it can be alternatively written in lowercase when used within a sentence.
Remember that the comma rules change when time zones are abbreviated — this will be further explained in a separate section later for clarity.
The time zone is spelled out and comes after a date
The second case that prompts pre-comma usage before time zones happens when they are used together with dates.
Dates are normally set off with commas when they appear in sentences. In the USA, the standard format for dates is “mm-dd-yyy” or “month-day-year.”
As dates within sentences are enclosed with commas, it follows that the date’s closing comma also serves as the pre-comma for the time zone.
Note again that we are still talking about completely spelled-out time zones rather than those that are abbreviated.
Feel free to refer to the example below for more clarity:
Again, we it is also possible to write the time zone in lowercase for as long as it does not contain a proper noun.
Unline the word “Pacific,” “central” is a common noun, so its first letter should not be capitalized when choosing this format.
If the format above does not suit your preference, you may also alternatively enclose the time zone within parentheses.
This time, you should already get rid of your pre-comma so as not to defeat the purpose of your parenthetical marks.
There are also certain nuances on whether or not to use a comma before or after parentheses within a sentence. Feel free to read more about this some other time.
The time zone is spelled out and is used parenthetically
The next condition that guides the pre-comma placement with time zones is when it is used as a parenthetical expression.
This is actually the larger-encompassing rule that governs the last two specific conditions explained in the previous sections.
When a time zone is spelled out within a sentence, we are using it as a parenthetical or interruptive element to convey a clearer meaning.
In other words, the commas that we use around a spelled-out time zone are simply used to mark and suggest its grammatical “unimportance.”
Parenthetical expressions are grammatically dispensable information pieces that we simply use to “accessorize” our sentences.
That said, the pre-comma and even the post-comma are both mandatory when time zones are used in such way.
The next example shows this condition more clearly:
Bear in mind the optional way of writing a parenthetical time zone within a sentence, which also entails a bit of attention on capitalization rules.
The time zone spelled out and comes after an introductory expression
Last but not least, a comma is necessary before a spelled-out time zone when it comes after an introductory expression, which is almost self-explanatory.
We use introductory expressions in our sentences to offer initial context to our reader. Clearly, this is the easiest to remember among all the conditions mentioned.
As you may figure, offsetting introductory expressions with a comma allows readers to have a smooth transition when connecting the relationship of ideas.
So, you should always use a pre-comma before the time zone when it appears after an introductory expression, such as in the next example.
Of course, you may also choose to write the time zone in lowercase as long as it does not have a proper noun in it.
A comma should not come before a time zone when…
Since we have already discussed when to appropriately use a comma before a time zone, we should also talk about when we need to leave the comma out.
There are two conditions that make this rule true. This happens either when the time zone is abbreviated and used with a clock time as well as when it is used as a restricted part of a sentence.
Let’s look into each of these conditions more closely below.
The time zone is abbreviated and comes after the clock time
When an abbreviated time zone is used after a clock time in a sentence, a comma before it should not be used anymore.
This is because we are already treating the abbreviated time zone as a part of the clock time entity rather than the whole sentence per se.
At 08:30 a.m. UTC, the conference began.
Apparently, this is a less confusing way when it comes to using punctuation marks; however, an unfamiliar reader may not necessarily understand what the abbreviation stands for.
Certain abbreviations can also stand for different time zones (e.g., PST for either Pacific Standard Time or Philippine Standard Time).
So, you had better steer clear of abbreviations when it is your first time exchanging messages with someone from another time zone to prevent miscommunication.
The time zone is a restricted part of the sentence
Finally, no comma should be used before a time zone when it is used as a restricted part of a sentence.
What “restricted” means is that the time zone is an essential part of the sentence, such as a subject or an object.
Unlike parenthetical expressions, restricted expressions are necessary in completing the meaning of the sentence, hence the comma omission.
This is also more of a straightforward condition, so there should be no need to go deeper with this one. But, you may also refer to the next two examples for clarity:
The company’s reference for their online meetings is Eastern Standard Time.Pacific standard time is used in Tijuana, Mexico.
Frequently Asked Questions on “Comma Before a ‘Time Zone’”
Is Pacific time capitalized in a sentence?
The word “Pacific” in “Pacific Standard Time” is a proper noun, so it should be capitalized when choosing to write the time zone in its complete rather than abbreviated form. Its remaining phrase “Standard Time” can be optionally written in lowercase or “standard time.”
How do you write two time zones in an email?
One time zone can be written in the host sentence, and the other can be enclosed with parentheses afterward. For example, you can say: “Let us touch base tomorrow at 06:00 p.m. UTC (02:00 p.m. EST).”
How do you clarify time zones?
To clarify time zones, it is best to write or mention the two separate time zones: one time zone is the message sender’s, while the other time zone is the message recipient’s.
Time zones are naturally confusing entities, so, as humans, we can only make them less ambiguous by making our writing more accurate.
The next time you need to use one and forget whether or not to use your commas, feel free to go back to this page as your reference.
Hey fellow Linguaholics! It’s me, Marcel. I am the proud owner of linguaholic.com. Languages have always been my passion and I have studied Linguistics, Computational Linguistics and Sinology at the University of Zurich. It is my utmost pleasure to share with all of you guys what I know about languages and linguistics in general.