iPad taking long to charge, but my charger or iPad battery?

[WhiteIphone5]

I lost my iPad charger while riding the train, with that being said today I used my iPhone charger (cube) and charged my iPad. I went to sleep at 1:30an est and I plugged in my iPad which was at 2%. I wake up now 8:10am do its been about 6+ hours and its at 67%. Is this normal or is it that my iPhone charger not transferring as much voltage as the one for iPad,? This seems like an obvious answer but I want some feedback
Thanks

 

[shadowjeff]

Yea it's because of the voltage differences. The ipad uses a 10W charger, ipad 4 uses 12 W charger, whereas the iphone uses only a 5W charger. So chargining an ipad with an iphone charger will definitely be much slower.