Horizontal: Vertical::3:2
The National Flag of India is a horizontal rectangular tricolour of deep saffron, white and India green; with the Ashoka Chakra, a 24-spoke wheel, in navy blue at its centre. It was adopted in its present form during a meeting of the Constituent Assembly held on 22 July 1947 and is called Tiranga in Local Indian languages which means Tricolor.
It was designed by Pingali Venkayya and has a proportion of 3:2. Following is the sample image of Indian National Flag (source: WIKI) -