PCB Trace Width & Current Calculator
Use this free online PCB Trace Width Calculator to determine the required trace width for your target current. Instantly calculate trace resistance, voltage drop, and power dissipation based onr IPC-2221 formulasr — for both internal and external copper layers.
Input Parameters
Strictly follows the IPC-2221 standard.
1 oz/ft² of copper thickness is equivalent to 1.378 mils or 0.035 mm.
Calculation Formulas (IPC-2221)
First, calculate Area (A)
Then, calculate Width (W)
Where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves.
- k = 0.024
- b = 0.44
- c = 0.725
- k = 0.048
- b = 0.44
- c = 0.725
Frequently Asked Questions (FAQ)
What is a PCB Trace Width Calculator?
A PCB Trace Width Calculator is an essential engineering tool used to determine the minimum required width of a copper trace on a Printed Circuit Board (PCB). It ensures that the trace can safely carry a specific amount of electrical current without overheating, preventing board failure or delamination.
How does the IPC-2221 standard work?
The IPC-2221 is the generic standard for printed board design. This calculator uses the proven IPC-2221 charts and formulas to map the relationship between current carrying capacity, copper cross-sectional area, and the allowed temperature rise. It provides the most reliable baseline for standard rigid PCBs.
Why is there a difference between internal and external traces?
External traces (on the top or bottom layers) are exposed to air, allowing them to dissipate heat through convection much more effectively. Internal traces are embedded within insulating core/prepreg materials (like FR4), which trap heat. Consequently, internal traces require significantly more width (more copper area) to carry the same current at the same temperature rise.
What is "Temperature Rise" (Temp Rise)?
Temperature rise refers to the maximum allowed increase in temperature of the trace above the ambient room temperature while operating. For standard FR4 boards, engineers typically design for a 10°C to 20°C temperature rise to maintain long-term reliability.
Can this tool calculate PCB trace resistance and voltage drop?
Yes. After entering your current, copper thickness, temperature rise, and trace length, the calculator automatically outputs trace resistance (in Ω), voltage drop (in V), and power dissipation (in W) for both external and internal layers. This helps you verify that your power delivery network stays within acceptable loss limits before sending your design to fabrication.