Hi and welcome
Well thats a very subjective question because it depends on lots of things, including how old the battery is.
With my own HTC Desire, with HEAVY use , screen on a lot, data/wifi on and using maps GPS etc - generally playing with the phone it lasts a few hours (certainly less than 10)
With the phone on standby but doing nothing with, screen and data off, it stays on standby for several days
Not sure if this helps, but there is no right answer
Roger