How is the waiting period (iddah) calculated in Hijri months?

If you are pregnant, your 'iddah (waiting period) ends upon giving birth to the entire pregnancy, as Allah Almighty says: "And for those who are pregnant, their term is that they deliver their pregnancy." (Quran 65:4) If you are not pregnant, your 'iddah is four months and ten days, as Allah Almighty says: "And those of you who die and leave wives behind - they, [the wives], shall wait four months and ten [days]." (Quran 2:234)

If the husband's death occurred on the 14th of Jumada al-Akhirah, 1435 AH, then the 'iddah begins immediately from that date and ends on the 24th of Shawwal, 1435 AH, at the exact time the death occurred, if Jumada al-Akhirah was thirty days. However, if it was twenty-nine days, then the 'iddah extends to the 25th of Shawwal. The remaining months are calculated by the sighting of the crescent moon, whether they are thirty or twenty-nine days.