Trace Width Calculator
How wide does a trace need to be to carry a given current without overheating the board? This calculator solves the IPC-2221 external and internal copper charts both directions — enter a current and copper weight to get the minimum trace width, or enter a width to find its current-carrying capacity. Useful the moment you're laying out power distribution, or checking a design against fab-house constraints before or after boards come back.
Trace Width
IPC-2221 charts — solve for required width or a trace's current capacity
Show your work
Solve for
Layer
Required width
30.8 mil
Required width
0.781 mm
Cross-section
42.4 mil²
Resistance
32.1 mΩ
Voltage drop
64.1 mV
Dissipation
128 mW
IPC-2221 is a conservative DC estimate for a bare trace in still air. Internal layers derate to roughly half the external current for the same geometry. Add margin for long runs, adjacent heat sources, and pulsed loads.