Firdar (Fidaria) are periods of life that fall under governorship of the planets as chronocrators (givers of life). A medieval technique attributed to the Persians, this and several similar methods of assigning planetary periods were used in various predictions.

Diurnal nativities begin with the Sun and nocturnal nativities begin with the Moon. The planetary periods follow the order: Sun, Venus, Mercury, Moon, Saturn, Jupiter, Mars, North Node, South Node. Apart from the inclusion of the nodes this is the order by which planets are assigned to the dignity of face. The periods of rulership are as follows:

Sun - 10 years
Venus - 8 years
Mercury - 13 years
Moon - 9 years
Saturn - 11 years
Jupiter - 12 years
Mars - 7 years
North Node - 3 years
South Node - 2 years

Thus a diurnal birth will recognise the Sun as the firdaria for the first 10 years of life after which rulership will pass to Venus on the 11th birthday and then to Mercury on the 19th birthday. A nocturnal birth will recognise the Moon as the firdaria for the first 9 years after birth, with rulership passing to Saturn on the 10th birthday, and so forth.

During its period of rulership the firdaria is claimed to have a heightened influence upon the native.

Corruptions of the term including fridaries and alphradar are also found.