It is in agreement with the previously present Laurent Longre algorithm through the year 6553 and with the alternative method of determining the date of Easter presented by the ASSU (which follows this code).Speed: The average time to execute was 7.8114 microseconds (7.8114E-06 seconds).To handle years from 1583 to 9999, you can remove the JLatham date check, and replace the last line with the following code: 3.To get dates for Easter in the Julian calendar (326 to 1582), use the ASSA table methodology (not their code, which is Gregorian only) and for dates after 1582 use the USNO or modified Longre code Accuracy: I have taken the view that this is an accurate algorithm for all years after 1899 through the Excel year limit of 9999.They provide a method involving the use of tables to accurately determine its date for any year from 1583 through 4099.I have adapted their BASIC formula for use as an Excel UDF also.Before moving on to the other solutions, let us look at the apparent limitations of the various worksheet function solutions.It may very well be that these worksheet functions meet your needs and you don't need to look further.
So in the final analysis, the worksheet formulas cannot be used reliably to determine dates of Easter after 2203, with two failures occurring as early as 2079 The most authoritative sources for algorithms suitable to be used as an Excel User Defined Function (UDF) would appear to be the work done by J. Oudin who tackled the inaccuracies in the formulas original derived by C F Gauß. This algorithm has been turned into an Excel UDF more than once - and was the one I elected to implement as an Excel UDF.
United States Naval Observatory Algorithm Astronomical Society of South Australia Algorithm Norman Harker adaptation of Claus Tondering Algorithm Excel Easter Calculation Workbook Excel Function Tutorials Thanks to Excel MVP, Jerry Latham, who contributed this tutorial for calculating Easter dates.
As Chip Pearson noted on his website, finding the day of Easter Sunday is a trivial effort but finding the date of a specific Easter Sunday is not such a trivial effort.
After 2203 it disagrees with other results almost routinely.
=DOLLAR(("4/"&A2)/7 MOD(19*MOD(A2,19)-7,30)*14%,)*7-6 This is the Thomas Jansen formula and is reputed to be accurate from 1900-2078. In point of fact it appears to be accurate through 2203 as with the previous formula.
=DATE(A2,3,29.56 0.979*MOD(204-11*MOD(A2,19),30) - WEEKDAY(DATE(A2,3,28.56 0.979*MOD(204-11*MOD(A2,19),30)))) This is the Gerhardt Somitsch formula and is accurate from 1900-2203. =FLOOR("5/"&DAY(MINUTE(A2/38)/2 56)&"/"&A2,7)-34 This is an adaptation of the winning contest formula, =FLOOR(DAY(MINUTE(J/38)/2 56)&"/5/"&J,7)-34 that is presented on the Chip Pearson website.