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Date Formats: Little-Endian, Middle-Endian, Big-Endian

Date Formats: Little-Endian, Middle-Endian, Big-Endian

Published Aug 30, 2020
Last Updated Jun 27, 2025
4 min read

In the Becoming A Proofreader course, we look at how date formats differ between American English, British English, and Australian English. There are, though, more than three countries in the world, so it’s worth looking at regional date format variations more generally.

Luckily, there are only three basic date format styles you need to know:

Little-endian (i.e., day-month-year)
Middle-endian (i.e., month-day-year)
Big-endian (i.e., year-month-day)

Read on to find out more about regional date formats and how to proofread them.

What Is Little-Endian Date Format?

A little-endian date format starts with the day, followed by the month, followed by the year:

day-month-year

dd/mm/yyyy

You can write little-endian dates with either numerals or words, although words are considered more formal:

We held an auction on 2 March 2025 to raise funds for the charity.

We held an auction on 02/03/2025 to raise funds for the charity.

Little-endian date format is the standard date format in the UK and Australia, as well as in most other countries! It is therefore the correct date format for most English-language writing outside the USA.

What Is Middle-Endian Date Format?

A middle-endian date format starts with the month, followed by the day, followed by the year:

month-day-year

mm/dd/yyyy

Here are our previous examples, but this time in middle-endian format:

We held an auction on March 2, 2025, to raise funds for the charity.

We held an auction on 03/02/2025 to raise funds for the charity.

Middle-endian date format is standard in the USA and some US territories.

It’s worth noting, though, that some US-based organizations prefer to use the international date format (more on this below!) or a little-endian format. For example, the US military uses a little-endian format.

What Is Big-Endian Date Format?

A big-endian date format starts with the year, followed by the month, followed by the day:

year-month-day

yyyy/mm/dd

It would be quite rare to see a date written out like this in English, but you may see the numeric version used:

We held an auction on 2025/03/02 to raise funds for the charity.

Big-endian date formats are used, for instance, in Asian countries such as China, Japan, and Korea.

This is also the style used by the international date format, which we’ll look at next.

How To Write the Date in International Format

The international date format (ISO 8601) provides a standard way of writing dates that works across borders, so it is commonly used by government organizations and global businesses.

International date format always uses the format YYYY-MM-DD, which helps to remove any ambiguity regarding the date denoted:

We received the report on 2020-07-10.

Dates that use this format are sometimes presented as a series of numbers with no dividers:

We received the report on 20200710.

This format is fine even if it looks unusual, but consistency and clarity are still important.

Proofreading Regional Date Formats

As we mentioned above, most of the world uses the little-endian format. But if you want to double-check the preferred date format for a particular country, there are handy lists of international date formats by country online.

Ultimately, the date format in a document will usually match the dialect (e.g., little-endian for British and Australian English and middle-endian for American English). From a proofreading perspective, though, the key things to check in terms of how a client uses date formats are whether:

The date format is consistent with the client’s style guide (if applicable).
The date format used is suitable for the document’s audience and purpose.
Date formats have been used consistently in the document.

If you spot any problems and there is a clear solution (e.g., one date in a document is inconsistent with the others), you can usually correct it.

Becoming A Proofreader

Our Becoming A Proofreader course includes a lesson dedicated to writing numbers – from dates and times, to measurements, percentages, fractions, and more. In fact, Becoming A Proofreader covers everything you need to know to become a successful proofreader, including: