How to judge the number of words in a document according to its size?

Hehe, the document size is related to the number of words. Usually, how many k's are there in the txt document we are talking about? The relationship between this K word and the number of words is 1k=5 12, because 1024 bits, real-time 1024 bytes, each Chinese character consists of 2 bytes, so there is such a conversion relationship.