Date order

10,000-year-old Mesolithic stone calendar, found in Scotland and believed by archaeologists to be the world’s oldest calendar discovered to date

As a proofreader of English texts, on a daily basis, I work on manuscripts written in both the UK and US versions of the language. The choice of which version of English to proofread in is always determined by the client, for example, because of their geographical location or their publisher’s style rules.

I briefly touched on the so-called ‘divided by a common language’ debate in my earlier blog, English sans frontières. That said, nothing so clearly confirms which version of English a text is (supposed to be) written in quite like date formatting.

In short, UK English uses the ‘DD/MM/YYYY’ format, while US English uses the ‘MM/DD/YYYY’. There does not appear to be a simple or single explanation as to why US English has adopted this format. Moreover, despite the variety of date formats used around world, the USA would appear to be the only country to insist on using ‘MM/DD/YYYY’.


Borrowing a term from computer technology, itself inspired by Jonathan Swift’s 1726 satire, Gulliver’s Travels, the UK date format is an example of little-endianness, while the US format is middle-endian. Incidentally, China uses the ‘YYYY/MM/DD’ format, which is big-endian.


Back to the topic in hand. As well as making sure that the date format corresponds to the version of English you are writing in, there are punctuation issues that need to be taken into consideration when writing the date with a mix of numbers and words.

Take today’s date, for example:

30(th) January 2018 (in UK English), but January 30(th), 2018 (in US English)

In the former, a comma before 2018 is unnecessary, as a single date in the UK format is a complete unit, not a list. In the latter, however, there is the potential for the month number to run into the year number.

Tip: While there are set rules in English grammar, which must be obeyed, it is also appropriate to be common-sensical: think of a comma in the same way as taking a breath when a sentence is read aloud.


Then there’s the ‘to/through’ phenomenon. In many instances, such as when advertising an event, an en dash will suffice to convey a span of dates:

UK English

1(st)-30(th) January 2018

30(th) January-1(st) February 2018

US English

January 1(st)-30(th), 2018

January 30(th)-February 1(st), 2018

In UK English, the en dash is read as ‘to’, while, in the US version, it is read as ‘through’. Thus, when writing the above dates without using an en dash, they will appear as follows:

UK English

1(st) to 30(th) January 2018

30(th) January to 1(st) February 2018

US English

January 1(st) through 30(th), 2018

January 30(th) through February 1(st), 2018

What about punctuation after writing the date? That will depend on where the date is located in a sentence. In the case of the US format, the year will almost certainly be followed by either a comma, (semi)colon or a full stop; for the UK format, what follows the date in terms of punctuation is less certain.

Here are some examples to help you work out what you need to do:

UK English

On 30 January 2018, I wrote a blog.

I wrote a blog on 30 January 2018.

US English

On January 30, 2018, I wrote a blog.

I wrote a blog on January 30, 2018.

Get in touch

I hope this discussion on how to correctly format dates when writing English, depending on whether the UK or US version of the language is used, has been helpful. If you have any comments on this or another topic related to writing in English, please feel free to contact me.

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Dr Stephen Gregson
Co-founder and Chief Proofreader & Editor
Language and Culture

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