the ratio of the width of national flag of india to its length is
Two by three
Flag of India
According to the Flag code of India, the Indian flag has a ratio of two by three (where the length of the flag is 1.5 times that of the width). 
wiki:6457823
Flag of India [SEP] Design and construction details
According to the Flag code of India, the Indian flag has a ratio of two by three (where the length of the flag is 1.5 times that of the width). All three stripes of the flag (saffron, white and green) are to be equal in width and length. The size of the Ashoka Chakra is not specified in the Flag code, but it has twenty-four spokes that are evenly spaced. In section 4.3.1 of "IS1: Manufacturing standards for the Indian Flag", there is a chart that details the size of the Ashoka Chakra on the nine specific sizes of the national flag.