Why Do Ramadan and Eid Move Earlier Every Year? The Islamic Calendar Explained

Why do Islamic holidays move earlier each year?

Islamic holidays — Ramadan, Eid al-Fitr, and Eid al-Adha among them — fall about 11 days earlier each Gregorian year. The reason is that they follow the Hijri calendar, which is purely lunar: twelve lunar months of roughly 29.5 days total about 354 days, some 11 days shorter than the 365-day solar year.

That 11-day gap accumulates. A holiday in mid-summer this decade will fall in spring the next, winter after that, and back to summer roughly every 33 years — the Hijri and Gregorian calendars realign only across a full generation.

Why the lunar calendar drifts

The Gregorian calendar is solar — it tracks the Earth's orbit around the Sun and adds a leap day to stay locked to the seasons. The Hijri calendar makes no such correction. It tracks only the phases of the moon: each month begins with the new crescent, and twelve of them fall short of a solar year by about 11 days. Because it is never adjusted back to the seasons, every Islamic date walks steadily backwards through the Gregorian year.

Why the date can differ by a day or two between countries

For many Muslims a new month begins only when the crescent moon is physically sighted, not when a calculation says it should appear. Sighting depends on weather, location, and the ruling of a national committee — so the same holiday can fall on slightly different days in different countries:

• Moon-sighting countries (e.g. Saudi Arabia, and much of the Gulf and South Asia) announce the date after an official sighting, which can move it by one or two days from the astronomical prediction.
• Calculation-based countries (e.g. Turkey, whose Diyanet uses astronomical calculation) fix dates in advance, so they may differ from sighting-based neighbours.

This is why holiday calendars show Eid on adjacent dates across countries, and why published dates carry a small margin of uncertainty until the sighting is confirmed.

The dates: how the shift looks

The table below shows the ~11-day annual regression across 2026 and 2027 (dates reflect the Saudi Arabia reckoning and may vary by 1–2 days elsewhere):

Islamic New Year (1 Muharram) follows the same rule. Every one of these dates will continue to fall earlier each Gregorian year until the calendars realign.

Frequently asked questions

Why does Ramadan start earlier every year?

Because the Islamic calendar is lunar and about 11 days shorter than the solar year. With no leap-day correction to hold it to the seasons, Ramadan — and every other Islamic observance — falls roughly 11 days earlier on the Gregorian calendar each year.

Why is Eid celebrated on different days in different countries?

Many countries begin the month only after an official moon sighting, which depends on weather and location, while others use astronomical calculation. The two methods, and local sighting conditions, can put Eid on adjacent days across borders.

When will Ramadan return to the same season?

The Hijri calendar drifts about 11 days a year against the Gregorian, so a given Islamic date returns to the same Gregorian season only after roughly 33 years — one full cycle through the solar year.

What is the difference between Eid al-Fitr and Eid al-Adha?

Eid al-Fitr marks the end of Ramadan (1 Shawwal). Eid al-Adha, about two months later (10 Dhu al-Hijjah), marks the culmination of the Hajj pilgrimage. Both move earlier each year by the same lunar rule.

Sources

• The Hijri calendar is a purely lunar calendar of twelve months (~354 days); dates depend on new-crescent visibility.
• Dates in the table are the Saudi Arabia reckoning from this site's 2026–2027 dataset and may vary by 1–2 days in countries that sight the moon independently or calculate it.

Related: what is Ramadan, what is Eid al-Fitr, what is Eid al-Adha, and public holidays by country.