The Mobile Device Portability Index (PI) boils down a device's portability into a simple number, where lower is better and a score of 100 is like the holy grail of portability. Here's how the PI score is calculated: (device volume / screen size) * (device weight / screen size) / battery size. If you don't care how big the battery is and want to remove it from the equation, then you can refer to the VS*WS column (the lower the better).
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