Wesley's Tool-Box

In the light of the upcoming Chinese lunar calendar support in iOS 8, I've cross-compared the Korean and Chinese lunar calendar data to see where exactly the two calendars differ. The chart below shows the result.

The difference mostly happens one lunar month at a time, during which the Korean lunar calendar trails the Chinese by one day. 2012 had a special case where the lunar month became different, as the Korean one had a leap third month while the Chinese one had a leap fourth month.

The chart covers all dates between 1901 and 2050 by the Gregorian (regular Western) calendar.

If you want to add this information to your calendar, use the following URL:
Lunar Calendar Difference ICS file

Download the ICS file and open up in your calendar app. If you're using Google Calendar, right-click and copy the URL first. Then on the "Other calendars" menu on the left side of the Google Calendar, click the drop-down button on the right and select "Add by URL". You can paste the URL there to add the calendar.


Calendar data compared were from:
Korean: Korea Astronomy & Space Information
Chinese: Hong Kong Observatory

As noted by Apple on the iOS8 announcement, using lunar calendar on the device will become easier. I'm sure a lot of the Koreans have been waiting for this. Until now, there hadn't been a system-wide support, so a user would have had to use an app that could display and manage this calendar on its own. This hassle should go away when the new iOS version arrives.

Sadly for the Koreans, this lunar calendar is being called "Chinese Calendar" on the system. Of course, if the user knows how to read basic Chinese glyphs, it isn't much of a practical issue. The dates mostly match, and the names of the year based on the sexagenary cycle are identical as well.

But the reason why this can't simply be generalized as "lunar calendar" is because it's based on measurements at Beijing, not Seoul. Because of the differences in latitude and longitude between the two capital cities, the phase measurements of the Moon slightly differ. In fact, the dates were off by a day for about five four months in 2012. Even with these downsides, Koreans end up benefitting from Apple's eager push into the Chinese market.

To use the lunar calendar, go to Settings > Mail, Contacts, Calendars > Calendars and select "Chinese" from the Alternate Calendars. After that, the lunar date will show in Chinese on the Notification Center below the regular date.

Meanwhile, if someone in your contacts keeps the birthday in lunar date, you can select "add birthday" to designate one. After that, the Calendar app will show that person's "Chinese Birthday" on the lunar birthday. I expect that this will be of much use to many Koreans.