PCB Trace Impedance Calculator

Calculates the characteristic impedance and per-unit-length parameters
of typical printed circuit board trace geometries.

Select a configuration:

Microstrip Trace

Embedded Microstrip Trace

Stripline Trace

Dual Stripline Trace








Geometric Parameter Definitions:

W: trace width
T:trace thickness
H (/H1)height of trace or dielectric above return plane
C:distance between the differential stripline pair
er:relative permittivity of the dielectric

Electrical Parameter Definitions:

Zo: characteristic impedance
Zc:effective characteristic impedance including the capacitance of distributed loads
Tpd:propagation delay
Lo:inductance per unit length
Co:capacitance per unit length




The source for formulas used in this calculator (except where otherwise noted) is the Design Guide for Electronic Packaging Utilizing High-Speed Techniques (4th Working Draft, IPC-2251, February 2001.

THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required.

This transmission line calculator was based on a concept developed by Douglas Brooks of UltraCAD Design, Inc.