50 ohm via calculator
There is no special via size for 50ohm traces. A via represents such a small part of the overall track impedance that the via can be ignored except for extremely high frequency signals. In those cases, the inductive and capacitive reactance of the via can be calculated, and controlled by placing/moving adjacent vias and structures. The inductance and capacitance of the via will be affected by the size of the anti-pads on planes, the length of the via, the diameter of the finished hole, the diameter of the via annulus, the dielectric constant of the board, and the distance to the return path for the signal which passes through the via.
If you want a simple free calculator that approximates the via reactances and impedance, you can download a copy from **broken link removed** .
If you want to see an example of what it takes to make a controlled impedance via, I suggest you look at: **broken link removed**