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PCB Design

Trace width calculator

Size a PCB trace for a current and temperature rise with the IPC-2221 formula.

About 10 min

Inputs

Copper weight
Layer

IPC-2221: A = (I / (k · ΔT0.44))1/0.725 mil², with k = 0.048 outside and 0.024 inside the board; width = A / (1.378 mil per oz × copper weight).

Result

Enter the current and allowed temperature rise, then press Calculate.

Reference: minimum widths for a 10 °C rise

CurrentExternal, 1 ozExternal, 2 ozInternal, 1 oz
0.5 A4.5 mil (0.115 mm)2.3 mil (0.058 mm)11.8 mil (0.300 mm)
1 A11.8 mil (0.300 mm)5.9 mil (0.150 mm)30.8 mil (0.781 mm)
2 A30.8 mil (0.781 mm)15.4 mil (0.391 mm)80.0 mil (2.033 mm)
3 A53.8 mil (1.367 mm)26.9 mil (0.683 mm)140.0 mil (3.556 mm)
5 A108.9 mil (2.765 mm)54.4 mil (1.383 mm)283.2 mil (7.194 mm)
10 A283.2 mil (7.194 mm)141.6 mil (3.597 mm)736.8 mil (18.715 mm)

Internal layers need roughly 2.6 times the width of an external trace for the same current, because the heat has to leave through the laminate.