Planning Holidays Across Two Calendars
Many families and workplaces live by more than one calendar. Lunar and solar dates drift against each other, so holidays need a little extra planning.
Solar and lunar years
The Gregorian calendar is the solar calendar used as the civil calendar in most of the world. The Islamic (Hijri) calendar is a lunar calendar of twelve lunar months in a year of 354 or 355 days. It is used to set the dates of Islamic holidays and observances.
Why the dates move
Because a lunar year is shorter than a solar one, a holiday fixed in the lunar calendar arrives earlier each year by the Gregorian count, moving through all the seasons over a cycle of years. Holidays planned "the same time as last year" will not be.
The sighting question
In many communities, the start of a lunar month depends on the sighting of the new crescent moon, so the exact date of a holiday may only be confirmed a day or so beforehand. Calculated calendars give an expected date; local announcements give the final one. Plan for a day either side.
Practical planning
- Add expected holiday dates to your calendar early, marked as provisional.
- Request leave with a little flexibility at both ends.
- Book travel with changeable tickets where the cost allows.
- Remember that banks and offices may close on holidays, so move payments and transfers earlier.
Showing both calendars
Many calendar apps can display an alternative calendar alongside the Gregorian dates, including lunar calendars. Turning this on makes it far easier to see when the two line up, and to explain dates to colleagues who use only one.
Fasting months and working hours
Some holidays are preceded by a period of observance that changes daily routines, such as meal times, sleep and working hours. If you plan meetings, deadlines or family visits during such a period, ask the people involved what times suit them, and avoid fixing important events at moments that clash with prayers or the breaking of a fast.
Workplaces with many traditions
Teams spread across cultures can keep a shared calendar of everyone's main holidays. It avoids scheduling an important meeting on a day half the team is celebrating, and it is a small, practical sign of respect.
Illustration only: if a lunar holiday fell in mid-spring one year, it would fall roughly a week and a half earlier the next year by the Gregorian calendar.
Revised 2026-11-09 · Hana Selwyn