could you please elaborate on how it is done?
Conversions may be made by using the Tabular Islamic calendar, or, for greatest accuracy (one day in 15,186 years), via the Jewish calendar.
Islamic calendar
Conversions may be made by using the Tabular Islamic calendar, or, for greatest accuracy (one day in 15,186 years), via the Jewish calendar. 
where did the tropical storm zelda strike? The Marshall Islands where is this place located? It is  near the Equator in the Pacific Ocean, slightly west of the International Date Line. what is the date line? It is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole. what is its purpose? It demarcates the change of one calendar day to the next. mention its significance in any major religion. In Islam, the day for holding the "Jumu'ah" prayer appears to be local Friday everywhere in the world. is there a specific calendar pertaining to this religion? Yes, the Islamic calendar. what are the applications? It is used primarily for religious purposes, and for official dating of public events and documents in Muslim countries. what are the important dates in it? UNANSWERABLE is it based on the sun or the moon? The moon - lunar calendar
wiki:7733365
Islamic calendar [SEP] Converting Hijri to Gregorian date or vice versa
Conversions may be made by using the Tabular Islamic calendar, or, for greatest accuracy (one day in 15,186 years), via the Jewish calendar. Theoretically, the days of the months correspond in both calendars if the displacements which are a feature of the Jewish system are ignored. The table below gives, for nineteen years, the Muslim month which corresponds to the first Jewish month. This table may be extended since every nineteen years the Muslim month number increases by seven. When it goes above twelve, subtract twelve and add one to the year AH. From 412 AD/CE to 632 AD/CE inclusive the month number is 1 and the calculation gives the month correct to a month or so.