PCB Trace Width Calculator
Calculate the recommended PCB trace width based on current, copper thickness, and acceptable temperature rise using IPC-2221.
Recommended Trace Width
PCB trace width is calculated using the IPC-2221 standard formula for external (outer) layers:
Area (mils²) = (Current / (k × ΔT^b))^(1/c)
Where for external layers: k = 0.048, b = 0.44, c = 0.725
Width (mils) = Area / (Thickness × 1.378)
Copper thickness is measured in ounces per square foot (oz/ft²):
- 1 oz ≈ 1.378 mils (35 µm)
- 2 oz ≈ 2.756 mils (70 µm)
Temperature rise is how much hotter the trace gets above ambient:
- 10 °C — conservative, recommended for most designs
- 20 °C — moderate
- 30 °C — aggressive, use with caution
Results are shown in both mils and mm.