A bit more information :
Connected to the more powerful iPad charger, my Tablet Z went from 44% to 78% in 2 hours, so about 17% per hour.
If you assumed that rate applies at all levels of charge, then 0% to 100% would take about 6 hours.
Now the iPad charger is about 33% more powerful than the Sony one...so for 0 to 100% with the Sony charger would be near 8 hours.
UPDATE: Forgot to mention - the above is with the device powered on, with screen off and WiFi on. So it should be better with the device completely off. ( I'm using a custom 4.3 ROM which has a bug which means I can only charge with power on at the moment.)
Phone : Nexus 4 (16GB) with PA ROM, Franco Kernel
Tablet : Xperia Tablet Z (311, 16GB WiFi only) PAC 4.3 ROM , TWRP recovery