PCB Trace Width Calculator (IPC-2221)
Enter the current, allowed temperature rise and copper weight.
Your numbers
Your results
PCB Trace Width Calculator (IPC-2221) by TheCalcTools
How the PCB Trace Width Calculator (IPC-2221) works
IPC-2221 relates current, temperature rise and copper cross-section with the curve fit I = k × ΔT^0.44 × A^0.725 (A in square mils; k = 0.048 for outer layers, 0.024 for inner layers). The width is the area ÷ copper thickness (1 oz = 1.378 mils).
It assumes still air and no nearby heat sources. The newer IPC-2152 gives more refined charts; add margin for high currents and keep traces short.
The formula
Worked example
Using the default values shown in the calculator:
| Current (A) | 2 |
|---|---|
| Temperature rise (°C) | 10 |
| Copper weight (oz/ft²) | 1 |
| Layer | External (outer) layer |
- 2 A with a 10 °C rise on 1 oz outer copper needs at least 30.76 mils (0.781 mm).
Result:
| Minimum trace width (mils) | 30.76 |
|---|---|
| Minimum trace width (mm) | 0.781 |
| Cross-section area (mils²) | 42.4 |
| Copper thickness (mils) | 1.378 |
Frequently asked questions
How wide for 2 A on 1 oz copper?
About 30 mils (0.77 mm) on an outer layer for a 10 °C rise.
Sources and further reading
- IPC-2221: Generic standard on printed board design (trace current curves)
- Digi-Key: PCB trace width calculator
- Wikipedia: Printed circuit board
Related calculators
More in Electronics & Engineering · All calculators
This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.