Voltage Drop Calculator

Calculate voltage drop across a circuit from source voltage, current, and total resistance.

Preparing Voltage Drop Calculator

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Input

Enter source voltage, circuit current, and resistance to estimate how much voltage is lost along the circuit path. This tool shows the result instantly without step-by-step output.

Input summary

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How to use Voltage Drop Calculator

Provide the electrical values, and the calculator will estimate the drop between the source and the load side of the circuit.

What this calculator is for

This calculator is for basic electrical design checks, classroom work, and troubleshooting when a load may be receiving less voltage than expected.

Tips

Use total circuit resistance for the run being analyzed instead of only one component if you want a realistic drop estimate.
A large voltage drop can point to undersized conductors, long runs, or unexpectedly high current draw.