The Islamic calendar, also called the Hijri calendar, is a lunar calendar used to identify Islamic months, religious occasions, and important dates such as Ramadan, Eid al-Fitr, Eid al-Adha, Ashura, and the Islamic New Year.
How the Hijri Calendar Works
The Hijri calendar contains 12 lunar months. A lunar month is based on the Moon's cycle and is usually 29 or 30 days long. Because a Hijri year is about 10 or 11 days shorter than a Gregorian year, Islamic dates move earlier through the seasons over time.
The 12 Hijri months are Muharram, Safar, Rabi al-Awwal, Rabi al-Thani, Jumada al-Awwal, Jumada al-Thani, Rajab, Shaban, Ramadan, Shawwal, Dhu al-Qadah, and Dhu al-Hijjah.
Why Islamic Dates Can Differ by One Day
Calculated calendars can estimate Hijri dates, but local religious authorities may confirm the beginning of a month through regional moon sighting. Weather, geography, observation standards, and national policy can therefore cause the announced date to differ by one day between countries.
ZaynClock provides a moon-sighting adjustment of minus one day, no adjustment, or plus one day. Use this only to match an announcement from a trusted local authority. For worship, fasting, Eid, or other religious decisions, follow the guidance used in your own community.
Umm al-Qura and Other Calculation Methods
The ZaynClock Islamic Calendar uses the browser's Umm al-Qura calendar calculation when it is supported. Umm al-Qura is widely used for civil date calculation in Saudi Arabia. Other regions and organizations may use different calculated criteria or direct observation.
No online calendar should be treated as a replacement for an official local announcement when a religious date depends on moon sighting.
How to Use ZaynClock's Islamic Calendar
Important Islamic Dates
Dates shown by an online calculator are planning references. Confirm locally observed dates with an appropriate mosque, council, or official authority.
Gregorian and Hijri Calendars Together
The Gregorian calendar is solar and is used internationally for civil scheduling. The Hijri calendar is lunar and is central to the timing of Islamic months and observances. ZaynClock lets you move between both calendar views without losing access to your regular event planner.
Use the Gregorian calendar for appointments and personal events, then switch to the Islamic calendar whenever you need a Hijri date reference.