In many -- possibly most -- calendar date picker widgets for U.S. users which display the selected date in month/day/year format, leading zeroes are shown when showing a single-digit month and/or day value. For example, the date March 1, 2018 would be rendered as 03/01/2018.

For example, here's the date picker on the expedia.com homepage (as of Feb 27, 2018):

expedia.com calendar date picker widget

However, most people (at least in the U.S.) don't actually write dates that way. They omit the leading zeroes, like 3/1/2018.

Is there a good reason that the MM/DD/YYYY format is in such common use in calendar date picker widets? Have there been any usability analyses done that point to one displaying leading zeroes -- or not -- as being superior from a UX perspective?

  • 1
  • 1
    @Garik, this question doesn't look like a duplicate of the question you mentioned. What do you find similar? Feb 28, 2018 at 4:14
  • 1
    @Wanda, this question is about reason of leading zeros in dates' presentation (3/1/2018 vs 03/01/2018) in a date picker, not about the order of days and moths. Feb 28, 2018 at 10:24
  • 1
    You're right. I'm not sure why I misread the question the first time. Apologies! Feb 28, 2018 at 10:45

2 Answers 2


A possible reason might be that such format is already commonly used, easy to be specify in a form for people to understand in what format a date is expected.

Most people would understand what MM/DD/YYYY or DD/MM/YYYY means, and how to fill a form that has a box where such format written in a light gray color in its background, whether it's on a paper sheet or a web site.

It's vice to take advantage of that, and allow a user just type a date not using a calendar date picker extra functionality.

Though there is no reason not to recognize a date like 3/3/18 automatically converting it to 03/03/2018 in a text field, it's reasonable to encourage some generic format, that is most commonly used.

That's said, the format MM/DD/YYYY use is quite questionable itself. Perhaps, it's isn't the best possible format, since it's not that easy to analyze briefly looking at it, especially, for international use, when flights formatted as DD/MM/YYYY used in a country and there is a probability that the days and moths should be read contrariwise. The more universal one seems to be YYYY-MM-DD that is lexicographical ordered by default.


The leading zeroes are from the days of paper forms, where each digit had its own box and data entry was more manual. The emphasis there wasn't necessarily the usability of the form for the person filling it out, it was on the data entry step that would follow.

In the digital context, the emphasis is on the usability of the form. No one has to decipher the user's entry and enter it somewhere else. So, unless there's a reason why a digital date-picking (or form-filling) experience would benefit from leading zeros, I'd advise leaving them out in favor of the more legible 3/3/2018 format.

The 3/3/2018 format feels more human, not only because its easier to read quickly, but also because it's what most (Americans) would probably write freehand. 03/03/2018 feels mechanical, like we're communicating with a system. We are, of course, but we certainly don't want our users to feel that way.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.