How to use commas in dates correctly

If it seems confusing to write out dates, you’re not alone: there are rules to using punctuation marks correctly when writing dates. However, without these consistent rules, the dates we need for invoices, statements, and other important forms might seem confusing. See where to put commas in a date and how punctuation fits with the weekdays and months we use so often.

American vs. international rules for dates

In American English, the formatting for dates is:

month/day/year

Elsewhere in the world (such as in British English), the date format is:

day/month/year

These different formats have separate rules. In American English, if you write out all three parts of a date, you will need commas to separate the day. If the sentence continues after the year on the end, another comma is required. See the following examples:

My birthday is on September 3, 1989.
On December 7, 1941, the United States entered World War II.
She started her current job on June 14, 2023.

However, if you’re writing for a British or international audience, you do not need any commas in the day/month/year format, such as in these examples:

Sean bought his car on 22 August 2022, according to the registration.
The Magna Carta was signed on 15 June 1215.
The dates of the festival are from 28 September to 4 October.

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Comma rules for dates in sentences

More specific rules exist for adding removing date information. For example, what if you include a day of the week? Then you will need a comma:

Next Friday, May 17, we are going to have a pizza party.
The date of her quinceañera is Thursday, February 1.

What if you only use a month and a year? Here, you don’t need a comma:

I moved to Seattle in August 2017, and then I moved to Austin in December 2019.
Since May 2009 my family has had a tradition of going to the lake house.

This same rule applies to a day/month combination. The following examples reflect this:

The last day to submit to the fellowship is February 10.
This year, Memorial Day falls on May 27.

“Ordinal numbers are frequently used in expressing dates. However, in formal or academic writing, ordinal numbers are unnecessary.”

How to use ordinal numbers

Ordinal numbers indicate the exact position of something or someone at a place compared to others. You might recognize these as the -st, -nd, -rd, and -th suffixes that go after numbers: 1ˢᵗ, 2ⁿᵈ, 3ʳᵈ, 4ᵗʰ, etc.

Ordinal numbers are frequently used in expressing dates. However, in formal or academic writing, ordinal numbers are unnecessary: the above examples have omitted ordinal numbers to clarify punctuation marks. Adding ordinal number suffixes does not change any of these comma rules.

Keeping dates and comma usage consistent is important in writing, especially depending on the audience you write for. Whether you’re writing an academic or research paper or writing for an American or British audience, understanding these quirks of the English language can add authenticity and reflect attention to detail. See more differences between American and British English by seeing whether you should use inquire or enquire, defense or defence, or the differences in how both countries use quotation marks.