Hi Seth,

I’ve made some experiments with IPC-D-317 and IPC2141A formulas that I compared to results from Polar Instruments SI9000, Hyperlynx, ICD stackup planner and Alter-PCB. After modeling IPC formulas with Excel, it was pretty easy to check results. All software using solvers give about the same results (around 1% error for any value of H, W, T, Er and S). IPC approximations are far from these commercial softwares. IPC formulas are a real nightmare to compute differential and asymmetric stripline impedance. Do you know what formulas are used in Kicad calculator?

For me three extra calculations are missing: signal velocity and trace inductance and capacity to prepare transmission line simulation with Spice.

Thanks again for the great job you’re doing at Kicad.

Mecagigi.