PCB Trace Width Calculator
Calculate trace width based on current and temperature rise (IPC-2221)
Input Parameters
Maximum continuous current
Typical: 10°C for sensitive, 20-30°C for power
Standard: 1 oz for signal, 2 oz for power
Internal layers have less heat dissipation
Calculated Results
Minimum Trace Width
Cross-Section Area
16.30 mil²
Resistance
0.042 mΩ/in
Voltage Drop
0.04 mV/in
Power Loss
0.04 mW/in
Trace Cross-Section
Quick Reference
IPC-2221 Formula
I = k × ΔT0.44 × A0.725
I = Current (Amps)
k = 0.048 (external) / 0.024 (internal)
ΔT = Temperature rise (°C)
A = Cross-section area (mil²)
Design Tips
- Add 10-20% margin to calculated width for safety
- Use 2 oz copper for power traces >2A
- Consider thermal vias for high-current traces
- Internal traces need ~2x width of external
Understanding PCB Trace Width
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