How to Convert a Hijri Date to the Gregorian Calendar

If you have a Hijri (Islamic) date — a birth date, a historical event, or the start of a month like Ramadan — and need to know where it falls on the ordinary Western calendar, you're converting between two calendars that count time in completely different ways.

Why the two calendars drift apart

The Gregorian calendar is solar: its year of about 365 days tracks the Earth's orbit around the Sun, which keeps the seasons fixed. The Hijri calendar is lunar: its twelve months follow the phases of the Moon, giving a year of about 354 days — roughly 11 days shorter.

Because of that 11-day gap, there's no fixed number of days you can add or subtract to convert between the two — the offset changes every year. Conversion has to count the actual lunar months that have passed, which is why a calculator is the practical way to do it.

What the Umm al-Qura calendar is

The Hijri to Gregorian converter uses the Umm al-Qura calendar, the calculated calendar maintained by Saudi Arabia and widely used for civil and planning purposes. It fixes month lengths by astronomical calculation in advance, rather than waiting for each new crescent moon to be seen, so dates can be worked out far ahead of time.

Why the observed date can differ by a day

In many communities the start of a Hijri month is set by the actual sighting of the crescent moon, which can fall a day before or after the calculated Umm al-Qura date depending on the weather and your location on Earth. So a converted Gregorian date is accurate for everyday purposes — planning, record-keeping, working out anniversaries — but the religiously observed date in your area may shift by about a day. Scholars differ on whether to follow local sighting, regional sighting or calculation, and this is a genuine difference of practice rather than a settled single answer.

Using the converter

1. Enter the Hijri day, choose the Hijri month, and type the Hijri year in AH (for example, 1448).
2. The converter returns the matching Gregorian date.
3. For the reverse direction — a Western date into the Islamic calendar — use the Hijri date converter instead.

To understand the calendar behind the conversion, read how the Hijri calendar works and our guide to the Islamic months. If you're converting a birth date, your age in the Islamic calendar explains why lunar and solar ages differ.