Dropping Resistor Calculator

Liguori Drag Racing • Electrical

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Dropping Resistor

Calculate series resistance and the heat produced at a known steady load.

Starting values are examples. Enter your measurements; results update as you type.

Method & assumptions

Ohm’s law at the entered steady current: R = voltage difference / current; heat = voltage difference × current. Suggested rating allowance does not replace temperature derating and mounting requirements. A series resistor does not regulate voltage when load current changes.