PCB Trace Width Calculator (IPC-2221 Method)

Current (A)

Allowed temperature rise (°C)

10 °C (conservative) 20 °C (typical) 30 °C (aggressive)

Copper weight

0.5 oz (17.5 µm) 1 oz (35 µm) 2 oz (70 µm) 3 oz (105 µm)

Trace location

External layer Internal layer Calculate Width

Method: IPC-2221 generic design formula I = k·ΔT^0.44·A^0.725 (k = 0.048 external, 0.024 internal; A in mil²). For boards above ~2 oz copper, high ambient temperatures, or sustained currents above 10 A, ask for an IPC-2152-based thermal review — the generic curves get conservative or unsafe at the edges. Internal traces need roughly twice the width of external traces for the same rise.

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