PCB Trace Width Calculator
Enter current, copper weight, and acceptable temperature rise to calculate the minimum trace width per IPC-2221. Shows both external and internal layer results with optional resistance, voltage drop, and power loss calculations.
Current (A)
Copper Weight
Acceptable Temperature Rise
Trace Length (Optional)
Enter trace length to calculate resistance, voltage drop, and power loss
Result
Trace Cross-Section Diagram
What is PCB Trace Width Calculation?
PCB trace width determines how much current a copper trace can safely carry without excessive heating. The IPC-2221 standard provides formulas to calculate the minimum trace width based on current, copper thickness, and acceptable temperature rise. Internal traces require wider widths than external traces because they have less heat dissipation.
How to Use the PCB Trace Width Calculator
- Select a current preset or enter a custom current value in amps
- Choose the copper weight (thickness) of your PCB — 1 oz is most common
- Select the acceptable temperature rise above ambient
- Optionally enter trace length to calculate resistance, voltage drop, and power loss
- Review the results for both external and internal layers
Frequently Asked Questions
What is the IPC-2221 standard?
IPC-2221 is the generic standard for PCB design published by IPC. It includes formulas for calculating minimum trace widths based on current capacity, which this calculator implements for both external and internal copper layers.
Why are internal traces wider than external traces?
Internal traces are surrounded by insulating material on both sides, which limits heat dissipation. External traces have one side exposed to air for better cooling. The IPC-2221 uses different constants (k=0.048 external, k=0.024 internal) to account for this.
What copper weight should I use?
1 oz/ft² (35 µm) is the most common standard PCB copper weight. For higher current applications, 2 oz (70 µm) or 3 oz (105 µm) copper is used. Thicker copper allows narrower traces for the same current.