Want to know how far your money would go in, say, 1980? Check out the Bureau of Labor Statistics’ inflation calculator: http://www.bls.gov/data/inflation_calculator.htm
Here’s their description of how the tool calculates inflation:
The CPI inflation calculator uses the average Consumer Price Index for a given calendar year. This data represents changes in prices of all goods and services purchased for consumption by urban households. This index value has been calculated every year since 1913. For the current year, the latest monthly index value is used.