These guides should help you understand how big fruit trees can get on different rootstocks.  The guides show the approximate maximum size a tree can get if "you just let it go!"  However, with proper annual pruning you can keep the tree smaller than its maximum and about 60-75% of its maximum growth.  These guides are approximate and based on Grandpa's experience in Southwest Michigan.

Climate also has a major influence, with drier Western climates resulting in smaller trees than humid Eastern and Mid-Western climates.  Western climates will often result in slower growth rate of about 75% of regions where rainfall is unlimited.

PLEASE GO TO THE "Rootstocks and Spacing Made Simple" page in the "Growing Tips" section for more information about specific characteristics of many rootstocks.