Angry Cat is approximately 6 1/2 inches tall. His bottom is approximately 4 1/2 inches by 5 inches (not including his tail).
The dimensions for the other rewards are as follows:
Postcards: 4 x 6 inches
Sticker Sheet: 4 x 5 inches
Buttons: 1 1/2 inches in diameter
Angry Cat poster: 11 x 17 inches
Starlight Fairy Cat poster: 8.5 x 22 inches
Angry Cat Phone Charms: Charms will be approximately 1.5 inches x 1.5 inches on a 2 inch black strap.
Sizes on the original artwork may vary, but most of the images are around 8.5 x 11 inches.