Conversely, what about: {date} is in the last week of {month}?

Is the first week of April the first week that is entirely in April or is it the first week that contains the first of April? Of course this all changes when considering whether the start of the week is Sunday or Monday.

There may not even be an "answer". In that case I'm interested in the most common usage.


This SO post and this mailing list are what have caused me to call the meaning into question in the first place.

3 Answers 3


In my (AmE) experience, the phrase is ambiguous and can mean any of the first week containing a date in April, the first week in which more days are in April than aren't, or the first week entirely contained in April, with the middle option being the most prevalent.

For example, if April 1 was a Friday or Saturday, in most circumstances, I would not expect the week of Mar 25/26-Apr 1/2 to be described as the first week in April.

Due to this ambiguity, this phrase is normally only used when giving rough estimates of dates where precision isn't necessary. If you want to precisely specify the range, use the actual dates.

  • +1 just for the middle one. I think anyone who said it was the first week just because it reached one day into the month would be barking mad, but I can certainly understand reluctance to entertain part-weeks, especially if it's only four days. Six days in should be a no-brainer though, so I can't quite accept your last definition either. Aug 12, 2011 at 0:01
  • ...I also think you're on shaky ground with "precision isn't necessary". A couple of days might not, but a whole week might well matter. Aug 12, 2011 at 0:03

People use it both ways. The most common way I hear it depends on the length of the first Monday-through-Friday week. If there are four or five weekdays in the first week, then it usually means the first week (Sun-Sat) containing any part of April. Otherwise, it means the first 7 days of April.

Sometimes people use it to make a date sound sooner, in which case it will mean the first 7 days of the month. For example, I may say your auto repairs will be complete in the first week of April. If April 1 is on Sunday, then you can pick up your car on Monday April 9th (since we're closed on the weekend).

Overall, I would say it varies dependent on regional, local, and family usage, and that both meanings are commonly considered correct.


The "first week of April" is the first week that contains any date in April. For example, in the image below the "first week of April" is the week containing the 1st, 2nd, 3rd, and 4th of April. It could also mean the first seven days of April -- April 1st through April 7th.

In this same image, the last week of April is the last week in a year that contains any date in April. In this calendar, it is the week starting on April 26th. Or, it could refer to the last 7 days of April. (Thanks to GEdgar for pointing this usage out).

enter image description here

If you wanted to talk about the first week that was entirely in April, you would refer to the first full week in April. The same goes for the last full week of April--it is the last week entirely contained within April.

  • So if Monday was defined as the beginning of the week the dates would be the 1st, 2nd, 3rd, 4th, and 5th for the first week?
    – Usagi
    Aug 11, 2011 at 20:01
  • @Usagi -- Yes. Starting on Sunday vs. Monday doesn't usually change things too much, though.
    – user10893
    Aug 11, 2011 at 20:04
  • 1
    Another meaning could be: April 1 through 7.
    – GEdgar
    Aug 11, 2011 at 23:26
  • 1
    This depends on the somewhat arbitrary concept that weeks start on Sunday, which to a great many people is untrue. In the UK (maybe because we're a bit less religious) I'm sure most people consider the week to start on Monday. Certainly nearly all the hundreds of bus companies I've worked with see it that way in terms of duty rotas and payroll weeks. Aug 12, 2011 at 0:08
  • 1
    In fact, a week can be any period of seven consecutive days. If I arrived in New York on a Wednesday, and now it is the following Wednesday, I can perfectly well say "I have been in New York for a week."
    – GEdgar
    Aug 12, 2011 at 13:56

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