Shohin-bonsai are 20 cm / 8 inches and under.
(Most important is that the Shohin fits with the size of the rack. 20 cm is the maximum height, but trees measuring up to 23-25 cm is also seen depending on their style).
(Mame Bonsai or bean-size bonsai is less than 10 centimetres / 4 inches in height. Also the with must not extend 10 cm / 4 inches but there are no official measures and it is just a guideline of the smaller shohin).
Not only the size is a measure of the bonsai belonging to the Shohin category. At the same time, the balance of the tree is important.
Example 1): You may have a tree where the width of tree is more than 40cm, but less than 25cm in height. The physical volume and size of the tree makes its all over volume to heavy to be a Shohin. Maybe the size is right regarding the height of the tree, but a heavy or massive root base makes the feeling of the tree out of style suiting the aesthetics of shohin-bonsai.
Example 2): The tree is maybe 30 cm in height, but because it is the “bunjin” style (“literati”), having few branches, little mass of leafs and therefore having the appearance of being a small thing (shohin), and acceptable as a shohin.
On exhibitions, also larger trees are exhibited. This is a list of the exhibited sizes that is used by the All Japan Shohin-bonsai Association:
Shohin-bonsai (up to 20 cm / 8 inch high)
Mini (maximum 10cm / 4 inch – the rules of measures are exact and also includes long Jins at Junipers e.g.)
Chuhin (middle size, maximum 45cm / 18 inch)
Kifu (over 20cm, / 8 inch - around 25-35cm / 10-14 inches)
Bunjin / Literati (may be up to 70-80 cm high / 27-32 inches but no exact demands in this group)
In Japan a registered collection of very high quality Shohin-bonsai is present at the All Japan Shohin-Bonsai Association. Excellent Shohin-Bonsai and pots are registered at Gafuten Yuga Collection, and in this case the more or less limited sizes are a little less important.
Basic guidelines of size qualification
It is to mention that the sizes described here are general and basic guidelines, because there are no official and exact classifications regarding sizes. In the case of exhibitions it is the judges and/or exhibition organisers alone who finally select the standards and judges the trees for selection.