Buffers are inserted into an integrated circuit chip design using a table that identifies buffer types based on buffer height, input capacitance, output capacitance and ramptime. A buffer routing tree is created having root, internal and leaf vertices. For each internal vertex, the initial circuit parameters are compared to circuit parameters associated with buffers identified in the table to identify whether a buffer identified in the table can be inserted to the respective internal vertex. If it can, an optimal insertable buffer is selected from the table and inserted to a selected internal vertex based at least in part on the comparison results. Also described is a computer process of creating the buffer type table.