Enter your PCB trace dimensions — length, width, and thickness — along with temperature and current, and this PCB Trace Resistance Calculator returns the trace resistance, resistance per unit length, voltage drop, and power dissipation so you know exactly how your copper trace will behave under load.
Trace Resistance
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Resistance per Unit Length
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Voltage Drop
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Power Dissipation
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PCB trace resistance is calculated using the formula: R = ρ × (L / (T × W)) × (1 + α × (T_amb - 25°C)), where ρ is resistivity, L is length, T is thickness, W is width, α is temperature coefficient, and T_amb is ambient temperature.
The main factors are trace length (longer = higher resistance), width (wider = lower resistance), thickness (thicker = lower resistance), temperature (higher temp = higher resistance), and material resistivity (copper has low resistivity).
Copper has a positive temperature coefficient, meaning its resistance increases with temperature. The standard reference is 25°C, and resistance increases by approximately 0.39% per degree Celsius above this temperature.
To minimize resistance: use wider traces, shorter routing paths, thicker copper (higher oz/ft²), keep operating temperature low, and use multiple parallel traces for high-current applications.
Voltage drop across a trace equals the current multiplied by the trace resistance (V = I × R). Higher resistance or current results in greater voltage drop, which can affect circuit performance.
Standard PCBs use 1 oz/ft² (35µm) copper. Use 2 oz/ft² (70µm) or thicker for high-current applications. Thicker copper reduces resistance but increases manufacturing cost.
Trace resistance is critical for power supply traces, high-current paths, precision analog circuits, and long traces. It affects voltage regulation, power efficiency, and signal integrity.