Calendar of Harptos

The Calendar of Harptos was the calendar used across most of Faerûn. It was created by the wizard Harptos of Kaalinth, although most people associate the word "Harptos" with the calendar. It was split into twelve months, each lasting three tendays (or thirty days). There were an additional five days that fell between months, bringing the total number of days in most years to 365.

Months and festivals
The names of the months and festivals used in Faerûn were as follows:
 * Hammer ("Deepwinter")
 * Midwinter between Hammer 30 and Alturiak 1
 * Alturiak ("The Claw of Winter" or "The Claws of the Cold")
 * Ches ("The Claw of Sunsets")
 * Spring Equinox on Ches 19
 * Tarsakh ("The Claw of the Storms")
 * Greengrass between Tarsakh 30 and Mirtul 1
 * Mirtul ("The Melting")
 * Kythorn ("The Time of Flowers")
 * Summer Solstice on Kythorn 20
 * Flamerule ("Summertide")
 * Midsummer between Flamerule 30 and Eleasias 1
 * Shieldmeet occurs the day after Midsummer, once every four years
 * Eleasis ("Highsun")
 * Eleint ("The Fading")
 * Autumn Equinox on Eleint 21
 * Highharvestide between Eleint 30 and Marpenoth 1
 * Marpenoth ("Leafall")
 * Uktar ("The Rotting")
 * Feast of the Moon between Uktar 30 and Nightal 1
 * Nightal ("The Drawing Down")
 * Winter Solstice on Nightal 20

Date conventions
The days making up a tenday did not have formal names. If precision was required, the number of the day and the number of the tenday were used, as in, "the fourth day of the first tenday of Flamerule". Days of the month were typically written as the numerical date followed by the month name, for example, "15 Hammer" or "". Informally or poetically this could be spoken or written as "".