CALCULATOR
PCB trace width calculator for current
Enter the current, the temperature rise you accept and the copper weight to get the minimum trace width by IPC-2221, then see which Thai plants publish that width.
Temperature rise allowed
Copper
Layer
0.78 mmminimum trace width · 30.8 mil
- Copper cross-section
- 42 mil²
- Resistance
- 31.4 mΩ
- Voltage drop
- 63 mV
- Power lost
- 126 mW
- Same current on an inner layer
- 2.03 mm
- This width in 2 oz copper carries
- 3.3 A
Every Thai plant that publishes a line width (5) can make 0.78 mm; 34 publish none. Compare the plants →
Method
IPC-2221 relates current to copper cross-section: I = k × ΔT^0.44 × A^0.725, with A in square mils, k = 0.048 for outer layers and 0.024 for inner layers. Width is the area divided by copper thickness (1 oz = 1.378 mil, 35 µm). Inner layers need about 2.6 times the width because the laminate around them holds heat. IPC-2152 (2009) is the newer method and allows narrower traces in most cases; IPC-2221 is the conservative default.