Le Leivre.com

Microstrip Impedance Calculator

Calculate Microstrip impedance for given PCB parameters.

w (mm)

t (um)
h (mm)




*Accurate for arbitrary values of Er and w/h ratios.
*Comparisons show minimal differences to ADS linecalc and Polar Instruments Quicksolver industry standard tools.
*Solder resist PCB coating will have the effect of lowering the impedance (due to the 30um or so of Er 3.5 resin). For resin coated boards, target 5-10% higher impedance using this tool.
*PCB vendors can use controlled impedances and will vary any designated trace width at mask level to hit impedance targets. For this reason, always err on the low impedance side so that vendor only makes trace width reductions thereby minimising potential layout infringements.
*1/2oz copper is approximately 17um thick.
*Typical plating of top surface copper is 40um thick.
*Equations from Brian C. Wadell, “Transmission Line Design Handbook”