Step-by-step method
- Always check units, prefixes and order of magnitude.
- Estimate minimum PCB trace width from current, copper weight and allowed temperature rise.
- Compare the result with temperature, tolerances and real conditions.
PCB trace width
Estimate minimum PCB trace width from current, copper weight and allowed temperature rise.
Calculate
Recommended width
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Copper area
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Resistance
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Loss
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Mistakes to avoid
- Always check units, prefixes and order of magnitude.
- Do not use an ideal result without margin or a datasheet check.
- Compare the result with temperature, tolerances and real conditions.
Component selection
Use at least the calculated width plus fabrication margin; increase copper or width to reduce loss and heat.
Worked example
At 2 A, 1 oz copper and a 10 °C rise, an external trace needs about 0.78 mm under the historical IPC-2221 relation.
Limits and safety
Always round up and verify against IPC-2152, stack-up, actual copper, vias and ambient temperature.
Technical sources
Do not use an ideal result without margin or a datasheet check.