USB charger for iPhone 5, do I need 1A or 2.1A?

[Lyn2012]

I'd like to be able to actually charge my phone while using it as a satnav. Will I need a more expensive 2.1A charger or will a cheaper 1A one still charge the phone?

 

[TG1]

1A should do you for the iPhone. This is what the stock wall charger provides. More amps would be needed for the iPad.

 

[Lyn2012]

Thanks. I just want to be sure as I remember reading somewhere that people find their phone charges very slowly if at all while using as satnav.