No—not that kind of date. I’m talking about the dates on the calendar—the ones we must write every day.

There are many ways to write dates. Let’s use the date on which I am writing this blog post (March 26, 2023) as an example.

The way I wrote the date above is probably one of the most descriptive ways to write a date (and would be even more descriptive if I added the day of the week: Sunday, March 26, 2023). This format is widely used in the United States. However, in many other parts of the world, the following is preferred: Sunday, 26 March 2023. The day comes before the month, with no comma after the month. You say tomato, I say tomahto.

A very common abbreviation for dates looks like this in the US: 3/26/2023 (or 3/26/23 if you didn’t live through the Y2K scare). Personally, I have never liked this format, though I wrote dates this way for decades when I was younger. It robs the month of its personality and replaces it with a dull number. “March” to me means St. Patrick’s Day, the beginning of spring, college basketball, and sometimes Easter. What is “3” supposed to mean?

Seven years ago, in order to update my laboratory skills, I took two courses in cell culture and biomanufacturing at a local community college. Early in the course, our professor taught us how we were to write in our lab notebooks, including dates. We had to write them like this: 26 Mar 2023. The day first, then the three-letter abbreviation for the month, then the four-digit year. The professor drummed the format into our heads to the point where I will only write the date in that format now, even seven years after I took the courses (and got A’s in each of them). Anything else just seems completely wrong.

Of course, if you are an editor, the way in which the date must be written depends on the style guide that your journal or book is using. Please check the style guide before correcting dates!

What is your preferred way to write dates?