[3] Persians, Azeris and Tats are the largest ethnic groups of people.

[4][5] According to some sources, the majority of people in northern Qazvin (Alamut) are Tats who speak a dialect of the Tati language.

[19][20][14] At the time of the 2006 National Census, the county's population was 530,961 in 142,781 households.

[2] Qazvin County's population history and administrative structure over three consecutive censuses are shown in the following table.

Media related to Qazvin County at Wikimedia Commons