Calendar Conversions

John P. Pratt
Updated 4 Nov 2016

This page is for doing calendar conversions. Some of the calendars included are our modern Gregorian, the old Julian (or Old Style), the Mayan and the Julian Day Number which astronomers use. These are all briefly described in the F.A.Q. page. Others are the Venus and Mercury calendars, and Enoch Calendar, which have been described in my articles. If you only see text on this page, chances are that you do not have java enabled, which is required for it to work. It probably won't run on smart phones; hopefully an app will be created which can.

Our Modern Gregorian Calendar

To use the conversion, select the calendar desired and click on "Create Calendar". You can create up to twenty calendar boxes, which are all linked to each other, so that if a date is entered in any one, it changes according in all the others. Be beware of a bug, which is after a date is entered in a box, it won't close until the browser is closed! Then just enter the date desired in the appropriate calendar box, and it will automatically be converted to the other calendars.

The format choices for each calendar are shown in the format menu. Remember for the Gregorian to always enter the entire year. If you enter 14Oct97 you will get A.D. 97. (Some of us do ancient history calculations!) Dates may be entered in quarter-day accuracy by adding am, pm, am*, or pm* after the date. The stars (*) refer to when it is dark and the *'s are shining.

The LAST and NEXT buttons increment the date by the number of days entered in the "Increment" input box. Primary holy days are shown in red and secondary in blue.


The Mayan calendar right now is only in English, but other languages may be added in later versions (like Mayan and Aztec). You may enter a date in one of four ways:

Some other calendars allow the date to be entered, which will change all dates on the row according. For example, the Venus calendar and Julian Day calendars allow that.