Calendario perpetuo
Daily perpetual calendar
Calendari: islamic, french revolution

Difference between dates

Date: / / /
(BC years must be entered according to astronomical notation)

Julian Day (at 12h):
Difference in days:
2th date: / /

Enter year, month, day, click "Compute J.D." and you will get julian day, week day and a time table of next Moons and Eclypses. For reverse operation enter julian day, then click "Compute Date".

Enter number n of days and click Sum to get date n days after; enter a second date an click Difference to get the number of days between the two dates. .

Astronomical eventsNotes

New Moon:
First quarter:
Full Moon:
Last quarter:

(Times are in U.T. i.e. Greenwich Mean Time; Moon phases are approximated with a maximum error of about 2 min; for Sun eclypses the visibility zone is largely approximate
if you want the eclypses of a given year, you can enter January 1, then May 1 and finally Sep 1, to get a complete list for the year).

This perpetual calendar calculates Julian Day, day of the week, next lunar phases and eclipses, given day, month, year; the passage from Julian calendar to Gregorian is fixed to Oct 4-15 1582. You can also enter Julian Day and calculate date.

For years preceding -45 (4BC), which was Julian Calendar beginning year, dates are computed according to a backdated Julian calendar, not Numan Calendar (information about the latter is really too limited).

For years between -45 (4BC) and 8AD I tried to take into account changes of month names and lengths and the error made by roman clergy in the compute of leap years (every three instead of four).