The question asks for the specific measurement of India's mainland extent from the east coast to the west coast.
India, being a large country, has significant dimensions. The distance from east to west refers to the span between its westernmost point and its easternmost point on the mainland.
The total distance covering this east-west span on the Indian mainland is approximately 2933 kilometers.
This measurement is a key geographical fact representing the width of the country.
Therefore, the actual mainland distance of India from east to west is 2933 km.