Height of the Bonsai

The name Bonsai conjures of miniature plants.  While bonsai trees are usually small, there can be bonsai up to a metres or a few metres high.  These are known as the Garden Bonsai.

Bonsai are classified on the basis of height.  It is a generally accepted rule of thumb that the height of the Bonsai should be six times or twelve times the diameter of the trunk above the ground. 
Thus the ratio of thickness to height should be 1:6 to 1:12
Bonsai are classified into the following categories based on their height. 

Name Size
Keishi less than 2.5 cms
Shito 2.5 to  7.5 cms
Mame 7.5 to 15 cms
Shohin 15 to 20 cms
Kifu Sho 20 to 40.5 cms
Chu 40.5 to 61 cms
Dai 61 cms to 101.5 cms

These rules are not rigid, It is not always possible to grow a bonsai tree to a specific limit. Thus, minor deviations are acceptable.  They factor is proportion.  They Bonsai needs to give an authentic appearance of a grand old tree.