Chihayafuru is an anime about card game called Karuta where players compete to touch the right card based on the poem being read. Chihayafuru wikia lists all 100 of the poem. However, I can't find the dimension of the card they use in the game. What is the dimension of the card used by Chihaya in the matches? Like how many cm x how many cm? If possible, the thickness of the card too.
Competition cards are 74x53mm (~2.9x2.1 inches) in size, and made from "pasteboard". Reference: Japanese Wikipedia article on karuta. The pasteboard used to make Japanese playing cards tends to be thicker than what we are familiar with in the West for cards. It's called 厚紙 (atsugami = thick paper) and can be quite thick -- I have some Japanese playing cards that are 0.4mm thick, which is thicker than Western plastic playing cards, and I've seen images of atsugami that look quite a bit thicker.
Alas I don't know exactly how thick karuta competition cards are since I never held any.