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PCB Trace Current Calculator

Find the current a PCB trace can carry (IPC-2221).

Trace width (mil)

Copper weight

Temperature rise (C)

Layer

Calculated Output

Max current (A) 1.464

Formula: I = k * dT^0.44 * A^0.725 (IPC-2221)

Step-by-Step Breakdown

1. Values used:

2. Trace width = 20 mil

3. Copper weight = 1

4. Temperature rise = 10 C

6. Max current = 1.464A

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The math behind it

I = k x (temperature rise)^0.44 x (cross-section in mils^2)^0.725, with k = 0.048 external, 0.024 internal.

A 20 mil, 1 oz external trace at 10 C rise carries about 1.9 A.

External vs internal?

External traces cool better, so they carry more current.