DanielNTX is right. Our toy has a 7000mAh Battery. The normal charger provides us with 2A per hour which - by using maths - makes the tab charge from 0-100 in about 3.5 hours (slightly more as you have to calculate efficiency loss and also the tab uses power during that time (Wifi, 3G, whatever's turned on)
Phone chargers usualy only deliver 500mA (or 0.5A) per hour, some more (The Blackberry charger provides 700mA for instance). Depending on how much Amp your phone charger provides, it can take longer, in the case of a 500mA charger it takes 4 times as long. (14 hours+).
It is really hard to find a good wallcharger that provides 2A that is not either flimsy as hell or pricy. HP had a firesale a few days ago where they sold their Touchpad charger (5.3V, 2A) for a cheap 5€ (including shipping) unfortunatelly my order got cancelled due to the high demand, but you should definatelly search for a charger with a higher amperage.
Phone: Nokia Lumia 920, retired my HTC 7 Mozart
Tablet: Acer Iconia W510 (Windows 8) - finally got rid of the horrible Samsung Galaxy Tab (P7510)