Holidays: How Difficult Can This Be?


It’s not difficult to predict that December 25 will be a holiday in London, or that July 4 will be a holiday in New York. So how difficult can it be, to do what we do?
Actually, keeping track of holidays around the world is highly complex.

There are hundreds of calendars in use around the world, all of which we must reliably implement. Some are relatively straightforward, such as the Chinese, Hebrew, and Julian. Others are very difficult, such as the Muslim and Hindu calendars.

For example, the Koran says that the month starts when the new moon is sighted. Many countries interpret this literally and send teams of observers each month to look for the new moon. If they sight the new moon, the month starts the next day. If not, the month cannot start yet.

From your local book store or the Internet, you can get highly accurate information about the date and time of the new moon. Sighting it by eye, however, is a very difficult feat to accomplish, made harder by factors such as weather, pollution and geography. If you use lunar tables to guess when the moon will be sighted, you may be correct 50% of the time…with a little luck.

Also, lunar tables cannot help with quirks, such as the fact that the start date of each month in Iran and Pakistan—neighboring countries—was different 36% of the time over the past 12 years.

We wanted to find a better way, so in 1997 we began a project that would provide greater accuracy.

After a decade of research, the result?
A proprietary technology that achieves the best accuracy money can buy.

Our Successes

Since 1998, we have predicted the start of the month with extremely high accuracy rates:

  • Iran: 96% accuracy
  • Pakistan: 90% accuracy
  • Morocco: 93% accuracy

Case Study: Hindu calendar


Of all the calendars in the world, the Hindu is the most complex. The religious calendar has many quirks, including days that range from 20 to 27 hours, and months that do not exist. Even the Indian government, which does the official calculations, does not know the dates more than 18 months in advance.

We have implemented a Hindu calendar that can predict dates out to the year 9999. How accurate is it? Going back to Indian independence in 1947, it has predicted the holidays with 98.5% accuracy. We have been working on the remaining 1.5% since 2007.