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
εr		relative permittivity of the dielectric

Electrical Parameter Definitions

Z0		characteristic impedance
Zc		effective characteristic impedance including the capacitance of distributed loads
Tpd		propagation delay
L0		inductance per unit length
C0		capacitance per unit length

Acknowledgements

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.