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<META NAME="description" CONTENT="Convert between the Traditional Chinese Lunar Calendar and the
Western Solar Calendar">
<META NAME="keywords" CONTENT="traditional lunar agricultural calendar gregorian julian solar chinese western converter year">
<TITLE>Western-Chinese Calendar Converter</TITLE>
<BASE HREF="http://www.mandarintools.com/" target="_top">
</HEAD>
<BODY BGCOLOR=LIGHTYELLOW>
<CENTER><H1>Western-Chinese Calendar Converter</H1></CENTER>
<CENTER>
<APPLET ALIGN=CENTER CODE="sinocalapplet.class" ARCHIVE="sinocal.jar" HEIGHT="340" WIDTH="570">
<FORM METHOD="POST" ACTION="http://www.mandarintools.com/cgi-bin/calconv.pl">
<TABLE ALIGN=CENTER CELLSPACING=5>
<TR>
<TD>Day <BR><INPUT TYPE="text" SIZE="3" MAXLENGTH="2" NAME="day"></TD>
<TD>Month<BR>
<SELECT NAME="month">
<OPTION VALUE="1"> January
<OPTION VALUE="2"> February
<OPTION VALUE="3"> March
<OPTION VALUE="4"> April
<OPTION VALUE="5"> May
<OPTION VALUE="6"> June
<OPTION VALUE="7"> July
<OPTION VALUE="8"> August
<OPTION VALUE="9"> September
<OPTION VALUE="10"> October
<OPTION VALUE="11"> November
<OPTION VALUE="12"> December
</SELECT>
</TD>
<TD>Year <BR><INPUT TYPE="text" SIZE="5" MAXLENGTH="4" NAME="year"></TD>
<TD>Era <BR>
<INPUT TYPE="radio" name="era" value="AD" checked> AD
<INPUT TYPE="radio" name="era" value="BC"> BC
</TD>
</TR>
<TR>
<TD COLSPAN="4" ALIGN=MIDDLE>
<INPUT TYPE="submit" NAME="julian" value="Julian Calendar">
<INPUT TYPE="submit" NAME="gregorian" value="Gregorian Calendar">
</TD>
</TR>
</TABLE>
This is just the first stage in what I hope to make a full featured
converter between any date in the Chinese and Western calendars,
including dynasty and reign title information. As it is now, you can
convert between the Julian (the system in use up till 1582) and the
Gregorian (the system in use from 1582 till the present) calendars and
see the Julian day. You can convert from any of these to the Chinese
cyclical year, month, and day, as well the solar month and day, with
dynasty and reign title.. I have also have links to other sites
dealing with Lunar and Western calendars, as well as my own brief
description of the Western solar and Chinese lunar calendar systems.
<P>
<STRONG>NOTE</STRONG>:
The conversion between Western and Chinese calendar systems is based
on complicated astronomical algorithms which I do not have. I use
tables to do the conversion.
<CENTER><H3>Western->Chinese Lunar Calendar</H3></CENTER>
<P>
<P>
Enter the Western date you want to convert to its Chinese lunar
equivalent. For an explanation on the difference between the Julian
and Gregorian calendars, see below. Most likely you will want to use
Gregorian calendar, the system in use in most of the world. This
converter currently will only work for dates from 1911 to 2050. <HR>
<P>
The page also includes a converter between the day in the Julian
Period and the Gregorian and Julian Calendars. For more information
on what this means, please see my explanation below.
<P>
Julian Date:
<INPUT TYPE="text" SIZE="10" MAXLENGTH="7" NAME="juliandate">
<INPUT TYPE="submit" NAME="julianperiod" value="Show Calendar Date"></TD>
</FORM>
<HR>
</APPLET>
</CENTER>
<P>
This converter does not work for dates before 1912 AD.
<P>
If the above applet does not appear, you probably need to update your browser.
You can also use the <A HREF="calconv_old.html">previous version</A> of the
calendar converter.
<HR>
<P>
Other sites with more information on the Chinese lunar calendar,
including some off-line converters, are:
<OL>
<LI><A HREF="http://www.amazon.com/exec/obidos/ASIN/0521777526">
Calendrical Calculations</A>: A book that describes algorithms for converting
between many different calendar systems, including the Gregorian and Chinese.
<LI><A HREF="http://emr.cs.uiuc.edu/home/reingold/calendar-book/second-edition/">On-line version of Calendrical Calculations</A>
<LI><A HREF="http://www.math.nus.edu.sg/aslaksen/calendar/chinese.shtml">The mathematics of the Chinese Calendar</A>: Excellent background information on Chinese calendar, including Mathematica packages.
<LI><A HREF="http://www.amazon.com/exec/obidos/ASIN/0935702687">Explanatory Supplement to the Astronomical Almanac</A>: Has a chapter on different calendar systems, including information on the Chinese lunar calendar.
<LI><A HREF="http://astro.nmsu.edu/~lhuber/leaphist.html">The Calendar Chapter</A> for the above book
<LI><A HREF="http://www.webexhibits.org/calendars/calendar-chinese.html">Site with good cultural and historical information about the Chinese calendar</A>
<LI><A HREF="http://www.sinica.edu.tw/ftms/luso.htm">2,000 Year Chinese-Western Calendar Converter</A> (in Chinese)
<LI><A HREF="http://weber.ucsd.edu/~dkjordan/chin/hbcalendar-u.html">The Chinese Calendar</A>: General background information
<LI><A HREF="http://www.njstar.com.au/calendar/">NJ Star Chinese Lunar Calendar</A>
<LI><A HREF="http://ourworld.compuserve.com/homepages/RaymondM">KAIROS Calendar Converter</A>
<LI><A HREF="http://www.friesian.com/chinacal.htm">The Solar Terms</A>
<LI><A HREF="http://www.cnd.org/Other/calendar.html">CND Printable
Chinese Calendars and Lunar Calendar Converter</A>
<LI><A HREF="http://www.freewarepalm.com/clock/lunarcalendar.shtml">Chinese Lunar Calendar for PalmOS</A>
<LI><A Href="http://www.ngai.f2s.com/chinese/lucal/">Utility that displays both the Gregorian and Chinese Calendar given a particular month</A>
<LI><A HREF="http://www.hermetic.ch/chcal/chcal.htm">Calendar Studies</A>: Information about various calendar systems. Very thorough.
<LI><A HREF="ftp://ftp.ifcss.org/pub/software/dos/cal">DOS Calendar Converters</A>
<LI><A HREF="ftp://ftp.ifcss.org/pub/software/unix/c-utils">Lunar</A>, an
UNIX Chinese/Western calendar converter. It also has a <A HREF="http://umunhum.stanford.edu/~lee/chicomp/lunar.html">web-based interface.</A>
<LI><A HREF="http://www.hko.gov.hk/gts/time/conversion1_text.htm">Gregorian-Lunar Calendar Conversion Tables (Years 1901-2100)</A>
<LI><A HREF="http://www.gio.gov.tw/info/festival_c/html_e/moon.htm">
Chinese Festivals and Holidays</A>
<LI><A HREF="http://www.asiasoft.com/English/chinese-holidays.html">Dates of Chinese festivals</A>
<LI><A HREF="http://www.123greetings.com/events/chinese_new_year/happy/">Chinese New Year electronic greeting cards</A> from 123Greetings.com.
</OL>
<P>
I'm interested in hearing your ideas and suggestions for this tool.
Please visit my <A HREF="contact.html">guestbook</A> with your
comments. If you came to this page directly, you might also want to
take a look at some of my other <A HREF="http://www.mandarintools.com"
target="_top">on-line Chinese tools</A>.
<CENTER><H2>The Western Calendar</H2></CENTER>
<i>Note</i>: This is only a general description of Western
calendar systems. Please consult a good reference work for more
detailed information (or send me an e-mail and I'll try to respond).
<P>
The calendar system currently in use by the United States and much
of the world is the Gregorian calendar. This calendar, based upon the
length of the Earth's revolution around the Sun (and hence called a
solar calendar) was instituted in October 15, 1582 AD by Pope Gregory
XIII as a reform to the previously used Julian calendar. Under the
Gregorian calendar, a solar year is divided up into 12 months of 30 or
31 days (with February having 28 or 29 depending on if the year is a
leap year). This gives a year of 365 or 366 days. However, the true
period of the Earth's revolution around the sun (measured from vernal
equinox to vernal equinox) is 365 days, 5 hours, 48 minutes and 46
seconds.
<P>
Over time this discrepancy would cause the official calendar to be
out of sync with various celestial events such as the equinoxes and
solstices. To rectify this, a series of leap years were added into
the calendar. On a leap year an extra day is added to the end of
February, February 29th. According to the Gregorian calendar, leap
years occur in every year divisible by 4, execept those that are
divisible by 100 but not 400. So 1900 was not a leap year, but the
year 1996 was a leap year and 2000 will be. These leap years keep the
calendar in sync with the solar year to an accuracy of about 1 day in
2500 years.
<P>
This system can be extrapolated backwards to produce dates
previous to 1582. In that case, 1 BC is a leap year, as is 5 BC and
so forth. My calendar converter can do this extrapolation back to
4713 BC, which is the start of the Julian period, explained below.
<P>
<CENTER>
<TABLE>
<TR>
<TD><STRONG>Month</STRONG></TD>
<TD><STRONG>Days</STRONG></TD>
<TD><STRONG>Month</STRONG></TD>
<TD><STRONG>Days</STRONG></TD>
</TR>
<TR><TD> 1. January</TD> <TD>31</TD><TD> 7. July</TD> <TD>31</TD></TR>
<TR><TD> 2. February</TD> <TD>28 or 29</TD><TD> 8. August</TD> <TD>31</TD></TR>
<TR><TD> 3. March</TD><TD>31</TD><TD> 9. September</TD> <TD>30</TD></TR>
<TR><TD> 4. April</TD> <TD>30</TD><TD>10. October</TD> <TD>31</TD></TR>
<TR><TD> 5. May</TD> <TD>31</TD><TD>11. November</TD> <TD>30</TD></TR>
<TR><TD> 6. June</TD> <TD>30</TD><TD>12. December</TD> <TD>31</TD></TR>
</TABLE>
</CENTER>
<P>
Before the Gregorian calendar, the Julian calendar had been in use
since it was instituted by Julius Ceasar around 45 BC. The principal
difference between the Julian and Gregorian calendars is the frequency
of leap years. Under the Julian system, every fourth year is a leap
year. This causes an error of about 1 day every 128 years. When the
Gregorian calendar was begun in 1582, this error had accumulated to 10
days. Hence, the last day of the Julian calendar, October 4, 1582 AD,
was followed the next day by the first day of the Gregorian calendar,
October 15, to rectify this error. Of course, it is possible to
extrapolate the Julian calendar forward and the Gregorian calendar
backward, to find a correspondence for days on either calendar, as the
above converter does.
<P>
The Julian period is sequence of days starting at day 0 on January
1, 4713 BC of the Julian calendar. Each day after this can be
associated with a unique Julian day. This system is useful in
astronomy and provides a useful starting point for conversion amongst
different calendar systems. The Julian day for December 31, 1996 is
2450449. Be careful not to confuse the Julian period with the Julian
calendar.
<CENTER><H2>The Chinese Lunar/Solar Calendar</H2></CENTER>
The traditional Chinese agricultural calendar is primarily lunar,
in that the lunar cycle (a lunation) between new moons is a principal
part of the calendar. This cycle averages 29.53 days, but can vary by
several hours for any given time of the year. A Chinese year normally
consists of 12 months where a month corresponds to one lunar cycle.
Each month starts on the day of the new moon. Since the cycle is not
an even number of days, a month in the lunar calendar can vary
between 29 and 30 days and a normal year can be 353, 354, or 355 days.
<P>
The Chinese agricultural calendar is also partially solar though
because 7 times in a 19 year cycle, an extra leap month (runyue) is be
added to the year to bring it back into line with the longer solar
year.
<P>
To explain the basis for determining when leap months are added,
one must first understand the Chinese system of solar terms. 24
dates, made up of 12 principal terms and 12 sectional terms, divide
the solar year into 24 periods that are based on the earth's position
around the sun. These include the equinoxes and the solstices.
According to the Chinese calendar, the winter solstice must occur in
month 11 of the year. A lunar month in which a principal term does
not occur becomes a leap (or intercalary) month and is assigned the
number of the month that preceded it but is designated as a leap. If
this happens to occur twice in one year, only the first month in which
it occurs in a leap month. The Chinese new year itself starts on the
second new moon after the winter solstice.
<P>
Chinese years, months, and days are also assigned a name based
upon the Chinese system of the heavenly stems and earthly branches.
In this cyclical system, each year, month, and day is associated with
one of the 10 heavenly stems and 12 earthly branches. Each successive
time period will have a new stem and branch, until going through the
stems 6 times and the branches 5 times, to give 60 unique
combinations. In the case of years and dates, this gives a
continuous cycle for thousands of years. This is similar for months,
but in the case of a leap month, it is assigned its previous month's
branch/stem combination with the leap designation added. This is why
the combination is so easily calculated for years and days, but requires
tables or complicated astronomical calculations to find months.
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