@User: The parasitic equations used by magic are not quite as complicated as those implemented in the Calibre decks; generally, this is not too bad of an approximation, but down at 130nm there is a noticeable difference in computed capacitance vs. actual parasitic capacitance between, say, a large plate (well modeled) and a minimum-width line (less well modeled). Other than the accuracy of corner cases, the parasitic modeling in magic is pretty good. To get full R-C extraction is a bit complicated in magic and will require a little hand-editing of the final netlist to replace the substrate node, which gets lost in the process. I intend to fix this problem in the next month or so, once the preparations for the current shuttle run stop being a major distraction.

ok sir ,i was trying to make sram cells using skywater pdk,but I was just not sure if spice netlist extracted would be fairly accurate,but yeah as per ur answer it seems fairly accurate thanks ,