PCB Trace Width Calculator

Enter your Current (I), Copper Thickness, Temperature Rise, Ambient Temperature, and Trace Length to find the minimum PCB Trace Width your board needs to carry that current safely — the calculator returns both Internal and External Layer Widths, Required Copper Area, and the corresponding layer resistance values for each.

A

Current that the trace must carry

oz/ft²

Thickness of the copper layer

°C

Allowable temperature increase above ambient

°C

Operating environment temperature

mm

Length of the trace for resistance calculations

Results

Internal Layer Width

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External Layer Width

--

Required Copper Area

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Internal Layer Resistance

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External Layer Resistance

--

Voltage Drop

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Power Loss

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Trace Width Comparison (Internal vs External)

Frequently Asked Questions

What is the difference between IPC-2221 and IPC-2152 standards?

IPC-2221 is the older standard that uses simplified formulas based on curve fitting. IPC-2152 is newer and more accurate, using finite element analysis. IPC-2221 tends to be more conservative (wider traces) while IPC-2152 provides more precise calculations.

Why do internal layers require wider traces than external layers?

Internal layers are surrounded by dielectric material and have poor heat dissipation compared to external layers which can dissipate heat to air. This means internal traces need to be wider to handle the same current without overheating.

What copper thickness should I use for my PCB?

Standard PCB copper thickness is 1 oz/ft² (35 μm). For high current applications, consider 2 oz/ft² or higher. Thicker copper allows narrower traces for the same current capacity but increases manufacturing cost.

How accurate are these trace width calculations?

These calculations provide estimates based on IPC-2221 formulas. Actual performance may vary due to factors like board stackup, via thermal effects, component proximity, and manufacturing tolerances. Always include safety margins in your design.

What temperature rise should I allow for my traces?

Typical allowable temperature rise is 10°C for most applications. For high-reliability designs, consider 5°C or less. Higher temperature rise (20-30°C) may be acceptable for less critical applications but can affect component reliability.

Do I need to consider trace length in my calculations?

Trace length is optional but important for calculating voltage drop and power loss. Longer traces have higher resistance, leading to more voltage drop and power dissipation, which can affect circuit performance.

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