sunnahfastEvery fasting day in the sunnah — the White Days, Ashura, Arafah, the six of Shawwal — lives on the Hijri calendar. Understand four things about that calendar and every "when is it this year?" question answers itself.
1. It follows the moon, not the sun
A Hijri month runs from one new crescent to the next, so it lasts 29 or 30 days — never more, never fewer. Twelve such months make a year of about 354 days, roughly eleven days shorter than the Gregorian year. That is why Ramadan, Ashura and the Hajj season arrive about eleven days earlier each year, slowly touring through all four seasons over a generation.
2. The day begins at Maghrib
An Islamic date starts at sunset the evening before its daylight. The night of the 13th comes before the day of the 13th — which is why a reminder for tomorrow’s fast arrives this evening, and why Jumuah’s special deeds begin on Thursday night.
3. Sighting and calculation can differ by a day
Communities begin the month either by physically sighting the crescent or by following a calculated calendar. The most widely used calculation is the Umm al-Qura calendar of Saudi Arabia — it is what sunnahfast computes with, from a table built into our server (no external services involved).
Because a local sighting can land a day before or after the calculation, two Muslims in different cities — or the same city — may genuinely hold different dates. Both are following valid positions; the practical advice is simple: follow your local community, especially for dates tied to congregational worship.
4. Syncing is a one-time setting
Every tool on sunnahfast — the reminders, the date converter and the calendar feed — accepts a ±1 day adjustment. If your community’s moon sighting runs a day ahead of or behind Umm al-Qura, set the offset once and every White Day, Ashura and Arafah reminder lands on your dates, not ours.
Tools that do the arithmetic for you
- The Hijri ↔ Gregorian converter on our home page works both directions, with weekday names.
- The upcoming fasting days page lists the next three months of sunnah fasting dates.
- The free .ics calendar feed puts the White Days, Ramadan, both Eids, Arafah and Ashura straight into Google, Apple or Outlook calendars — and keeps itself up to date.
- And the reminders themselves: an email or notification around 7 PM the evening before every recommended fast, Insha Allah.