PCB Trace Width

Results

Calculate the minimum PCB copper trace width required to safely carry a specified current without exceeding a given temperature rise. This calculator implements the IPC-2221 standard the globally accepted industry benchmark for printed circuit board design. Supports both internal and external layer calculations.

IPC-2221: Area (mil²) = [I ÷ (k × ΔTb)]1/c → Width = Area ÷ (Thickness × 1.378)

Results

How to use this calculator

Step-by-Step Instructions

1. **Enter the maximum current** The highest continuous current the trace must carry, in Amps.
2. **Set allowable temperature rise** 10°C is standard. Higher rises allow narrower traces but increase board temperature. Never exceed 30°C for most applications.
3. **Select copper thickness** Most standard PCBs use 1oz copper (35µm). High-current boards may use 2oz or 3oz.
4. **Select layer type** External layers dissipate heat better than internal layers, allowing narrower traces for the same current.
5. **Click Calculate** The minimum trace width is shown in mils (thousandths of an inch) and millimeters.

Worked Example

Carrying **2A on external 1oz copper with 10°C rise**:

Minimum trace width ≈ **25 mil (0.635mm)** round up to 30 mil for safety margin.

Pro Tips

Always add at least 20% safety margin to the calculated trace width for production reliability.

Internal layers need approximately 2× wider traces than external layers for the same current capacity.

For power supply traces carrying more than 5A, consider using copper pours (planes) instead of traces.