The New York Times "Calendar"

CALENDAR_NYT is a FORTRAN90 library which attempts to determine the date, given the volume and issue number of an edition of the New York Times, or vice versa.

You might think that all that is required is to figure out the first date of issue, and then count the number of days that have elapsed from then to the date of interest, to get the issue number. That's why I thought too, but it's not that simple by any means!

The routines YMD_TO_NYT and JED_TO_NYT are fairly trustworthy. The first routine immediately refers to the second, which has been compared to a sample of issue numbers of all the front pages issued in a recent commemorative book. The actual details of how the issue number was occasionally garbled, held back, or incremented involve about 30 corrections to the simplistic idea of counting the number of days from the first issue.

The "inverse" routines NYT_TO_JED and NYT_TO_YMD work from about 1905 onwards, after which there were only two disruptions to the simple issue incrementing. Before that time, the formula has not been "educated" about the various irregularities in the issue numbering system.

The routine JED_TO_NYT_ISSUE_IDEAL assigns to each successive issue of the New York Times a unique identifier, namely, its sequence number. This is what the nominal issue number was supposed to do. Using this function, we can see that the actual number of issues of the New York Times printed from the beginning up to 1 April 2008 was not 54,267, (the nominal issue number) but instead 56,570!


The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.


CALENDAR_NYT is available in a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

CALENDAR_RD, a C++ program which computes the representation of a given date in a number of calendrical systems, by Edward Reingold and Nachum Dershowitz

CALPAK, a FORTRAN90 library which converts between dates as computed on various calendars.

DATES, a dataset directory which contains lists of dates in various calendar systems.

DOOMSDAY, a FORTRAN90 library which is given the year, month and day of a date, and uses John Conway's doomsday algorithm to determine the corresponding day of the week.

WEEKDAY, a FORTRAN90 library which determines the day of the week for a given day.


  1. Anonymous,
    A Correction; Welcome to 51,254,
    The New York Times,
    01 January 2000, Volume 149, Issue 51254.
  2. James Barron,
    What's in a Number? 143 Years of News,
    The New York Times,
    14 March 1995, Volume 144, Issue 50000.
  3. The New York Times,
    Page One, 1896-1996, A Special Commemorative Edition Celebrating the 100th Anniversary of the Purchase of the New York Times by Adolph S Ochs,
    Galahad Books, 1996,
    ISBN: 0-88365-961-1,
    LC: D411.P25.
  4. The New York Times,
    The Complete First Pages, 1851-2008,
    Black Dog & Leventhal Publishers, 2008,
    ISBN13: 978-1-57912-749-7,
    LC: D351.N53.

Source Code:

Examples and Tests:

List of Routines:

You can go up one level to the FORTRAN90 source codes.

Last revised on 09 February 2009.