Accurate parasitics estimation for hierarchical customized VLSI design

Disclosed is a method of estimating interconnect wire parasitics in integrated circuits which includes obtaining a circuit layout having circuit components placed thereon including source input/output (I/O) pins and sink I/O pins, the circuit layout having a circuit hierarchy, bubbling up of the I/O pins until all I/O pins are on a same level of the circuit hierarchy, and then estimating interconnect segments to be employed in interconnecting at least some circuit components of the placed circuit components of the circuit layout. Also disclosed is a circuit design system and program storage device.