Sufficient Bone to Support the Weight of the Horse is necessary for Long Term Soundness.
Yardah on
Marjorie J Armstrong 2014
Yardah Stud
Updating & Developing Regularly
Measuring the bone/tendon front leg immediately below the knee is still a good test to check whether the horse has enough bone for its weight and for the work that it will be doing. It is particularly important in a breeding programme.

Bone strength is one of characteristics that have been considered in the development of this new Pure Spanish Warmblood horses.
The DNA of these horses is predominately from Andalusian and Thoroughbred horses. 
Height.  It is not much use to build a big high building if it is going to collapse due to insufficient foundations for the size of the building. 

The legs of the horses are the foundations of the structure.

Hopefully, you will find the table, measurements and estimation for weight useful. The only way you can correctly find the weight is to put the horse on scales.