Are "y", "m", and "d" the singular and plural abbreviations for "year(s)", "month(s)", and "day(s)"?


1. The project took exactly 5y 2m 18d to complete. (If this is in fact correct, would 'm' be confused for 'meter'?)

2. It was a 5y 2m 18d project.

Again, I was asked for exactness and specificity with regard to accuracy. I don't know why the boss likes this format, but for some inexplicable reason he does. Any help is greatly and deeply appreciated. You folks on this site are amazing. (Sorry, but I had to give you your props.) :-)

3 Answers 3


First, is it the right abbreviation? No. The common abbreviation is to use "yr" for year. As for the plural, we commonly use "yrs".

Now to your examples. They're both different.

In the first sentence, you'd write the full words like this.

The project took exactly 5 years, 2 months and 18 days to complete.

As for the second sentence, it would be written as:

It was a 5-year, 2-month and 18-day project.

You've said It was 'a', so you must use the singular form.

Now to the big question... Is your usage acceptable? Well, there two things I'd see here:

  1. Context
  2. Information format

If for example, you want to write this format of y, m and d in a computer-generated report, there's no problem. It saves on the ink and is understandable.

However, if you're writing this method in an English assignment, it wouldn't be a good idea to do so.

  • 1
    Wikipedia disagrees with your first pronouncement: 'There is no universally accepted symbol for the year as a unit of time. The International System of Units does not propose one. A common abbreviation in international use is a (for Latin annus), in English also y or yr.' Also, 'the abbreviations for units of measure are the same whether the units are singular or plural. [eg] The abbreviation is ft. whether it is foot or feet. [Grammar Girl] Commented Feb 27, 2014 at 16:42
  • The fact that the second example requires the singular forms has nothing to do with a project being singular. It is because the time measurements function as attributive adjectives here, and adjectives are not inflected for plural in English. “They were five-year projects” would still be correct, even though projects here is plural. Commented Feb 27, 2014 at 16:50

With any abbreviation, you're trading compactness and speed for aural equivalence.

Audience and context should be considered to avoid confusion. This means in general, one should use the most "generally accepted" abbreviations.

For years and months that is yr. and mo. You could be more compact with 2 yr. or less (but more equivalent) with 2 yrs./mos.

In context, nobody is going to think 5y 2m 18d means 5 years, 2 meters, and 18 days.

You would, however, get into trouble if you were to write "We don't have enough wood and will need 2m before we can complete the project."

Most important of all:

If your boss likes a certain format, USE THAT FORMAT.

  • 1. The project took exactly 5yrs 2mons 18days to complete. 2. It was a 5yr 2mo 18day project. "18 days" and "18day" look bizarre within this amalgamation of abbreviations. How'd we abbreviate "day" and "days" to symmetrically fit within these contexts? Commented Feb 27, 2014 at 15:41
  • I think they look fine like that. Commented Feb 27, 2014 at 15:42

These abbreviations are frequently used as placeholders for the individual digits of the date.

For example: an online form asking for your birthdate. Might have MM/DD/YY (or DD/MM/YY outside of the US) with a pull down menu or type in field to add those numbers.

I wouldn't call them the proper abbreviations, but I don't think anyone would have trouble understanding their use.

  • Final question on this. Would anybody personally support the punctuation in EVERY example below? The project lasted 2 hours 5 minutes 20 seconds. a 2-hour 5-minute 20-second marathon The project lasted 1 year 8 months 3 days. a 1-year 8-month 3-day project If we use 'and', I think the following could work without the commas. Agreed? a 1-year 8-month and 3-day project The project lasted 2 hours 5 minutes and 20 seconds. a 2-hour 5-minute and 20-second marathon Commented Mar 1, 2014 at 14:13

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