CO2 comes in different sizes. a single, that's 1, 16gram cartridge should inflate a 700cx23 tire to about 130 psi and for a chart for different sizes and applications. Just click on inflation chart. they are compact and easy to use.
here ya go
http://www.genuineinnovations.com/co2-refills/12-gram-co2-threaded-cartridge-display-box-of-30.html