A PCB trace width calculator helps you determine the minimum copper trace width needed to safely carry a given current on your printed circuit board. Using the industry-standard IPC-2152 formulas, this tool accounts for copper thickness, allowable temperature rise, and layer placement to give you accurate trace width, cross-section area, resistance, and voltage drop values.
Trace Parameters
Detailed Results
Internal vs External Comparison
| Parameter | External | Internal |
|---|
IPC-2152 Formula Reference
Cross-Section Area Formula
| Constant | External | Internal |
|---|---|---|
| k | 0.048 | 0.024 |
| b | 0.44 | 0.44 |
| c | 0.725 | 0.725 |
Trace Width from Area
Copper Thickness by Weight
| Weight | Thickness (mils) | Thickness (μm) |
|---|---|---|
| 0.5 oz | 0.689 | 17.5 |
| 1 oz | 1.378 | 35.0 |
| 2 oz | 2.756 | 70.0 |
| 3 oz | 4.134 | 105.0 |
| 4 oz | 5.512 | 140.0 |
How to Use the PCB Trace Width Calculator
Designing a PCB with traces that are too narrow can cause overheating, board damage, or even fire. This PCB trace width calculator uses the IPC-2152 standard formulas to determine the minimum trace width required for a given current, helping you design safer, more reliable circuit boards.
Step 1: Enter the Current
Specify the maximum current your trace needs to carry in amps. This should be the peak continuous current for that part of your circuit. For example, a power supply trace carrying 2A to a microcontroller requires a wider trace than a signal line carrying a few milliamps.
Step 2: Select Copper Weight
Choose the copper weight of your PCB. Standard boards use 1 oz/ft² copper (1.378 mil thick). Heavier copper like 2 oz allows narrower traces for the same current, but costs more to manufacture. Most hobby and prototype boards use 1 oz copper.
Step 3: Set Temperature Rise
Enter the allowable temperature rise above ambient. A 10°C rise is a safe, conservative choice for most applications. Higher temperature rise values allow narrower traces but mean more heat generation. For sensitive components or enclosed designs, keep this value low.
Step 4: Choose Layer Type
Select whether the trace is on an external layer (top or bottom of the board) or an internal layer. External layers dissipate heat better because they are exposed to air, so they can use narrower traces. Internal layers need wider traces to carry the same current safely.
Step 5: Review Results
The calculator shows trace width in both mils and millimeters, the cross-section area, trace resistance per inch, and voltage drop per inch. A comparison table shows both internal and external layer results side by side so you can see the difference. Always add a safety margin of 10 to 20 percent to the calculated minimum trace width to account for manufacturing tolerances and real-world conditions.
Practical Tips
For power traces carrying more than 1A, consider using copper pours or wider traces than the minimum. Check your PCB manufacturer's minimum trace width capabilities, which are typically 4 to 6 mil for standard processes. Use the resistance and voltage drop values to verify that your power delivery stays within acceptable limits for your design.
FAQ
Is this PCB trace width calculator free?
Yes, this calculator is completely free with no limits or account required. You can run as many calculations as you need for your PCB designs without any cost.
Is my data safe when using this tool?
Absolutely. All calculations run entirely in your browser using client-side JavaScript. No data is sent to any server, and nothing is stored or logged. Your design data stays on your device.
What standard does this calculator use?
This calculator uses the simplified IPC-2221/IPC-2152 equations for PCB trace width estimation. These are the industry-standard formulas used by PCB designers worldwide to determine minimum trace widths for given current requirements.
What is the difference between internal and external layers?
External layers are the top and bottom copper layers of a PCB that are exposed to air, which provides better cooling. Internal layers are sandwiched between insulating material with less heat dissipation, so they require wider traces to carry the same current safely.
What temperature rise should I use?
A temperature rise of 10 degrees Celsius is a common conservative choice for most designs. For high-reliability applications, use 5 to 10 degrees. For less critical designs, 20 to 30 degrees may be acceptable. Higher temperature rise allows narrower traces.
How does copper weight affect trace width?
Heavier copper (higher oz/ft2) means thicker traces, which can carry more current in a narrower width. For example, 2oz copper can carry the same current as 1oz copper with roughly half the trace width. Standard PCBs use 1oz copper.
Should I add a safety margin to the calculated trace width?
Yes, it is recommended to add a 10 to 20 percent safety margin to the calculated minimum trace width. The IPC formulas provide minimum values, and real-world factors like manufacturing tolerances, ambient temperature, and nearby heat sources can affect performance.
Can I use this for high-frequency RF designs?
This calculator determines trace width based on current-carrying capacity only. For RF and high-frequency designs, you also need to consider impedance matching, which depends on trace width, dielectric thickness, and material properties. Use a dedicated impedance calculator for those requirements.