Countdowns

Some celebrations land on the same calendar day every year: Christmas on December 25, Halloween on October 31, Valentine's Day on February 14 and New Year's Day on January 1. Once the day has passed, their countdown simply rolls on to the next year.

Others move. Thanksgiving in the United States is fixed by a 1941 law to the fourth Thursday of November, so it falls between November 22 and 28, and Black Friday follows it. Western Easter is the first Sunday after the ecclesiastical full moon on or after March 21, which puts it anywhere from March 22 to April 25. Lunar New Year starts on the new moon that falls between January 21 and February 20. Ramadan follows the Islamic lunar calendar, which is about 11 days shorter than the solar year, so it arrives earlier each year and cycles through all seasons in roughly 33 years. Diwali is set by the Hindu lunisolar calendar and usually falls in October or November.

Holidays begin at midnight wherever people are, not at one global instant. Someone in Sydney opens presents on December 25 about 16 hours before someone in Los Angeles. Counting to your own midnight makes the numbers match what you will actually experience. The Friday countdown is the exception: it counts to 17:00 on Friday, the traditional end of the working week.

For moon-based events the dates shown are the expected ones. Ramadan in particular is confirmed by local moon sighting and can begin a day later in some countries.

Days-left numbers are handy for shopping, travel and leave requests, but sometimes you need the gap between two arbitrary dates, such as a booking and a deadline. The days between dates calculator counts calendar days or weekdays for any pair you choose.