Why Trace Width Matters
In PCB design, the width of copper traces directly affects how much current they can safely carry. An undersized trace can overheat, causing board damage or even fire. Understanding trace width calculations is essential for every PCB designer.
IPC-2221 Standard
The IPC-2221 standard provides formulas for calculating minimum trace width based on current, acceptable temperature rise, and copper thickness. The key formula considers:
- Current (in Amps)
- Acceptable temperature rise (typically 10°C or 20°C)
- Copper weight (1oz = 35μm thickness)
- Whether the trace is internal or external
Rules of Thumb
For external layers with 1oz copper and 10°C rise:
- 1A → ~10 mil (0.254mm) trace width
- 2A → ~30 mil (0.762mm) trace width
- 5A → ~100 mil (2.54mm) trace width
Use Our Calculator
Don't guess — use our PCB Track Calculators to get precise trace width values for your specific design requirements.