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Why is mm/dd/yyyy date format is dumb?

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In this article at OpenGenus.org, we have explored why the date format MM/DD/YYYY is difficult to interpret and should not be used. The other 2 date formats are consistent.

Table of contents:

  1. 3 date formats
  2. Why is MM/DD/YYYY dumb?
  3. Issues with American units

Due to mismatching date formats, programming systems handling dates is difficult.

3 date formats

There are three major date formats used today:

  • DD/MM/YYYY : (DATE followed by Month followed by Year)

The first 2 date formats are intuitive as:

  • DD/MM/YYYY : Increasing format
  • YYYY/MM/DD : Decreasing format

The last format MM/DD/YYYY is counter-intuitive and difficult to identify as distinguishing between date and month is difficult. As there is no fixed standard, these formats are used interchangeably.

In fact, all these formats are dumb and should not be used:


This format is not used anywhere: MM/YYYY/DD.

Countries where the 3 main date formats are used:

  • DD/MM/YYYY: India, Japan and other asian countries
  • YYYY/MM/DD: Hungary and many European countries
  • MM/DD/YYYY: USA, Canada (counter-intuitive)

Why is MM/DD/YYYY dumb?

Given a date, it is difficult to distinguish between MM/DD/YYYY or DD/MM/YYYY as there is a common range for date DD and month MM.

  • Range of date DD: 1 to 31
  • Range of month MM: 1 to 12

Date like 11/10/2023 or 05/04/2023 is difficult to identify the format as both MM/DD/YYYY and DD/MM/YYYY is consistent with the dates.

Dates like 14/05/2023 or 10/20/2023 are easy to identify as if the number is > 12, then it is definitely a date DD.

The problem is in countries like United States of America and Canada, many people (not all) use the format MM/DD/YYYY which makes it difficult to interpret dates.

This is not just a confusion at personal level but can cause problems at standard procedures. For example, one of our members went to USA and the date on a document was YYYY/05/11. The official interpreted the date to be 5th November but the actual date mentioned in other documents was 11 May. Due to this, the document was rejected.

Only two date formats should be used at max:


Issues with American units

This issue is not just with date formats but almost all metrics used in USA. These metrics in USA cannot be easily converted to other standard formats used across the World:

  • Length formats like inch, feet, yard, mile are difficult to convert to cm,mm, km
  • Cooking units like cups, tablespoons, pinches
  • Temperature unit like fahrenheit
  • Weight units ounces, ton to kg, gm
  • Time: In USA, week starts on Sunday. Rest of the World assumes week starts on Monday.

This confusion of date format is across many other units.

With this article at OpenGenus.org, you must have an idea what the problem with the date format. Use a consistent format.

Why is mm/dd/yyyy date format is dumb?
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