Gcal is a program for calculating and printing calendars. Gcal is a program for calculating and printing calendars. Gcal displays hybrid and proleptic Julian and Gregorian calendar sheets, respectively for one month, three months, or a whole year. It also displays eternal holiday lists for many countries around the globe, and features a very powerful creation of fixed date liststhat can be used for reminding purposes. Gcal can calculate various astronomical data and times of the Sun and the Moon for pleasure at any location, precisely enough for most civil purposes. Gcal supports some other calendar systems, for example, the Chinese and Japanese calendars, the Hebrew calendar, and the civil Islamic calendar, too.