Microstrip Impedance Calculator

About this calculator

A microstrip is a flat copper trace running above a grounded reference plane, separated by a dielectric substrate — the standard way to route controlled-impedance signals on a printed circuit board. Its characteristic impedance (Z0) depends on the trace width, the substrate's dielectric constant (εr) and thickness, and the copper thickness; this calculator applies the widely used Wheeler / IPC-2141 approximation to estimate Z0 from those physical dimensions.

Getting Z0 right matters whenever a trace needs to match the impedance of a driver, cable, or connector — commonly 50Ω for RF and general digital signaling or 100Ω differential for USB and Ethernet. PCB designers and RF/hardware engineers use impedance calculators like this one during stack-up planning, before finalizing trace widths in tools like Altium or KiCad, to avoid signal reflections that cause data errors or radiated emissions at high frequencies.