I believe it was stated in the movie that the chipmunks were 8" in height; that's about all the value of fun you will get from this predictable, annoying, sloppy and confusing picture. How are all these disconnected people related again? The acting was very poor, the live characters unbelievable and the plot (what little that existed) was very predictable. If you are a die-hard chipmunk fan, such as the school principal, then you will look over all of the flaws to adore your annoying furry shrieking singing rodents.
I suppose the real test that this movie failed was that my 5 year old daughter was bored less than half way through. The little 'timber tigers' could not keep her attention and quire frankly were... annoying.