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PCB trace width calculator (IPC-2221)

How wide a copper trace must be for a current.

Try the circuit in the labBuild it on the simulator's bench and measure it.

How it is worked out

IPC-2221 relates current, copper cross-section and temperature rise: I = k × ΔT0.44 × A0.725, with A in square mils, k = 0.048 for outer layers and 0.024 for inner layers (they cool worse).

Example: 2 A on 1 oz outer copper for a 10 °C rise needs about 0.78 mm. Signal traces of 0.25 mm carry about 0.7 A.

This is the classic conservative chart; IPC-2152 gives more detail (board thickness, planes nearby). Leave margin for hot enclosures.

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