The Common Calendar encompasses a year consisting of 364 days, split into twelve months of twenty-eight days each, and four seven-day festivals, each placed at three month intervals. Different cultures have their own names for the months and festivals though most human nations in the Flanaess subscribe to the names given below. The months and festivals are commonly referred to as the Dozenmonth of Luna and the Four Festivals.

The days are reckoned in weeks of seven days each. The days of the week are Starday, Sunday, Moonday, Godsday, Waterday, Earthday, and Freeday. Godsday is commonly associated with worship, and Freeday with rest. The remaining days are considered work days though many work through a large part of Godsday. An interesting feature of the Common Calendar is that the days of the week always occur on the same day every year, a result of the year having a number of days divisible by seven.

The months and festivals are based on the cycles of Oerth's moons, white Luna the Great Moon (also known as Raenei) and aquamarine Celene the Lesser Moon (also known as Kule and the Handmaiden). Luna has a twenty-eight day cycle, while Celene's cycle is ninety-one days. Celene is full at the midpoint of each festival, while Luna is full at various times throughout the year. Notably, both moons are full on Richfest 3-5.

There are Five Wandering Stars that travel through the Twelve Lairs of the Zodiac. Their names and colors are Edill (white), Gnibile (red), Conatha (blue), Ginsei (green), and Greela (green). The Twelve Lairs and their constellations and associated months are Cockatrice (Readying), Harpy (Coldeven), Ettin (Planting), Dryad (Flocktime), Manticore (Wealsun), Wyvern (Reaping), Dragon (Goodmonth), Unicorn (Harvester), Hydra (Patchwall), Chimera (Ready'reat), Kraken (Sunsebb), Basilisk (Fireseek).

The Dozenmonth and Four Festivals of the Year with the Phases of the Moons

Calendar of the Common Year - Important holidays and festivals are shown with the gods that the dates are sacred to in parentheses.