PCB Trace Width Calculator

Why Trace Width Matters

PCB trace width is critical for ensuring your circuit can handle the required current without excessive heating. An undersized trace can lead to voltage drops, signal integrity issues, and in extreme cases, trace burnout or fire hazards.

The IPC-2221 Standard

This calculator uses the IPC-2221 standard formula, which is the industry-accepted method for determining minimum trace width. The formula considers three main factors:

• Current: The maximum continuous current the trace must carry
• Temperature Rise: The acceptable increase in trace temperature above ambient
• Copper Thickness: Thicker copper can carry more current at the same width

External vs Internal Layers

External (outer) layers can dissipate heat more effectively than internal layers because they are exposed to air. This is why internal traces require approximately twice the width of external traces for the same current capacity.

Temperature Rise Guidelines

• 10°C: Conservative, suitable for precision analog circuits
• 20°C: Standard for most digital applications
• 30°C: Acceptable for power circuits with adequate cooling
• 45°C: Maximum recommended for most applications

Best Practices

• Always add a safety margin of 10-20% to calculated trace widths
• Consider using copper pours for high-current paths
• Use thermal vias to help dissipate heat from internal power traces
• Account for manufacturing tolerances in your calculations