Our first power check on the FirePod board said the copper was fine. It wasn't: the processor's core supply was losing half again as much voltage as its budget allowed, through pours and vias we had treated as perfect conductors.

kicad-irdrop reads a KiCad board with pcbnew, rasterises the pours, tracks and pads of one net on every layer, joins the layers through each via barrel, and solves the network for the load current you give it. You get the worst and median drop at the load pins, the effective resistance, vias over their IPC-2221 rating, where the loss happens, and a current-density map per layer.

On Antmicro's open-source LPDDR4 test board, the 1V0_SYS rail at 2 A drops 5.3 mV (2.67 mOhm) with no via overloaded, and halving the grid moves the answer about 1 %.

Python, Apache-2.0. Run it with the Python that ships with KiCad, or in your browser on Apify with nothing to install.