Convert between the Hijri (Islamic) and Gregorian calendars in either direction. Uses the tabular Islamic calendar with the Kuwaiti / Umm al-Qura type-IIc intercalation (years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29 of each 30-year cycle are leap, civil epoch 1 Muharram 1 AH = 622-07-19 Friday). Get the weekday in Arabic and English, day-of-year, day-of-week index, and a month-grid view showing Gregorian dates with Hijri overlays. Pure browser math — no server, no API. Note: observational sightings (Saudi Arabia, ISNA, MUIS) can differ by ±1–2 days from the tabular calendar.
Choose Gregorian month or Hijri month — the grid mirrors what you'd see in a printed calendar with the other system as a secondary overlay.
| # | Name (Latin) | Name (Arabic) | Significance |
|---|---|---|---|
| 1 | Muḥarram | مُحَرَّم | Sacred month — day 10 (ʿĀshūrāʾ) |
| 2 | Ṣafar | صَفَر | — |
| 3 | Rabīʿ al-Awwal | رَبِيع ٱلْأَوَّل | Day 12 = Mawlid (Prophet's birthday, Sunni) |
| 4 | Rabīʿ al-Thānī | رَبِيع ٱلثَّانِي | — |
| 5 | Jumādā al-Awwal | جُمَادَىٰ ٱلْأُولَىٰ | — |
| 6 | Jumādā al-Thānī | جُمَادَىٰ ٱلثَّانِيَة | — |
| 7 | Rajab | رَجَب | Sacred month — day 27 Isrāʾ wal-Miʿrāj |
| 8 | Shaʿbān | شَعْبَان | Day 15 Laylat al-Barāʾah (Mid-Shaʿbān) |
| 9 | Ramaḍān | رَمَضَان | Fasting month — last 10 nights incl. Laylat al-Qadr |
| 10 | Shawwāl | شَوَّال | Day 1 = ʿĪd al-Fiṭr |
| 11 | Dhū al-Qaʿdah | ذُو ٱلْقَعْدَة | Sacred month |
| 12 | Dhū al-Ḥijjah | ذُو ٱلْحِجَّة | Sacred — Hajj 8–13, day 10 = ʿĪd al-Aḍḥā |
The tabular calendar uses an arithmetic 30-year cycle: years {2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29} are leap (kabīsah) with 355 days; the other 19 are common with 354 days. Within each year odd months are 30 days, even months are 29 days, except in leap years month 12 (Dhū al-Ḥijjah) gets a 30th day.
Conversion goes via the Julian Day Number: JDN(H) = floor((11y + 3) / 30) + 354y + 30m − floor((m − 1) / 2) − 385 + d + EPOCH where EPOCH = 1948440 (1 Muḥarram 1 AH = Friday 16 July 622 Julian = 19 July 622 Gregorian, JDN 1948440).
From JDN, recover the Hijri year via y = floor((30 · (JDN − EPOCH) + 10646) / 10631), then derive month and day from the day-of-year.