The number of Representatives allocated for each state is determined by its population size, but each state is automatically entitled to at least one Representative. The number of Senators allocated for each state is two, regardless of population size. See: http://www.ask.com/wiki/United_States_Congress.
The amount of representatives that each state has in congress varies, such as California has 53 and New York has 29. To view the complete list, please visit the website http://www.house.gov/representatives/.