vvarrior:
int conversionFactor = 3.3/1023;
The "long" format for conversionFactor (instead of "int") was discussed already, which is nice. And the "5V" value was discussed as well, which means that it'll be a good idea to indicate why you used a '3.3' value in the first place.
Also, if you want to follow the same way that the internal D-to-A hardware (of the successive approximation A-to-D) does its digital to analog voltage conversions........which is what the hardware actually does (internally) .... then go for:
5/1024
Whoever put in '1023' at this site here accidentally got it wrong ..... [u]Analog Read Voltage Example[/u] and it should be amended so that it becomes '1024'.
(google resistive ladder, R-2R digital to analog conversion etc.)
It's not going to make much difference which one you use, but good to know that the hardware involves 5/1024 (for the voltage resolution). So if the hardware operates in that way, then might as well use the formula associated with it. And - when doing A-to-D, we don't usually make the input signal (or voltage) go all the up to roof (ceiling) anyway.