Cropping to 4x6 on iPhoto on new iPad
I’m new to Apple and I bought the new iPad. I downloaded the iPhoto app and I have a question about cropping. I would like to print 4x6 pictures, but I do not see that size option in iPhoto. I do see 2x3 as a choice. Will that be sufficient or will the printed 4x6 photgraphs be grainy or lose details? Thank you very much.
iPhoto '11