The construction of the Borobudur must have been a gradual building process, which took approximately fifty years to complete the monument. The reason of this lies in the fact that there were not always enough workers available during this period of time. Also, at the time of building a part of the construction collapsed, which lead to a delay and repeated periods of inactivity in the process. Furthermore, sometimes the unexpected circumstances even required a change of the original plans.
Since there already was a large quantity of volcanic rock available in the area, it is not surprising that the Borobudur’s construction is built solely from this type of stone. These stones sometimes could weigh well over a hundred kilo each, and were transported to the building site by using wooden carts to carry the heavy load. It is not so easy to determine the exact number of workers involved in the construction work, but it is assumed that one single worker could transport one rock a day, and so it is estimated that were approximately one hundred workers involved in this activity alone. Thus, in order to get all the required rocks onto the artificial hill, it would take an estimated thirty years or more to complete the task.
Then, there were another hundred men needed to load the heavy rocks onto the wooden carts, and would unload them again once they arrived at the construction site. Thus, all in all, an estimated number of two hundred men were involved in this activity. Due to the weather conditions (of dry and wet season) they could only work at the Borobudur for a period of six months a year; because most of the workers themselves were actually farmers they were occupied with the cultivation of their rice fields during the other six months of the year.
The number of artisans, who, for example, took care of the refinement of the temple reliefs – of which there are 1460 in total at the Borobudur - is estimated to be relatively small. Though it is impossible to confirm an exact number, it is, however, suggested that there must have been a group of approximately ten artistic specialists. If we assume that these artisans worked at a steady paste, then it is possible they completed all the Buddha images on the Borobudur within a period of five years.
It is likely that the head artisan divided his students in several groups; the teacher first drew the outlines of the particular scene, then his students had to refine their master’s design. Yet, they were not allowed to complete the reliefs, for this had to be done by the master himself. Then there were still other workers who were involved in rendering and painting, something which now remains hardly seen on the monument.
All the various types of workers involved in the building of the Borobudur were under direct supervision of the architects and religious authorities at the Royal Court of the Sailendra King. However, it is important to mention that none of these workers were actually forced to do the work; though they did not get paid by the King, yet they voluntarily applied for the jobs, for they considered this particular type of work as an extraordinary opportunity to gain valuable (spiritual/religious) merit and virtue.