Voltage Drop Calculator
Estimate how much voltage may be lost over a wire run based on voltage, current, distance, material, and wire size.
Voltage drop is the small loss of voltage that happens as electricity travels through wire. Long runs and smaller wire can increase that loss.
Enter the circuit details to find a recommended minimum wire size.
Recommended result
Minimum wire size
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Voltage drop
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Percent drop
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Longer runs increase voltage drop, and smaller wire increases voltage drop too. Lower drop is generally better for performance.
Nearby size comparison
Run the calculator to compare the recommended size with one size smaller and one size larger when available.
How to read this
Longer runs create more resistance in the circuit
Smaller wire sizes create more voltage drop
Lower percent drop is generally better
This estimate uses common wire resistance values
This calculator is intended as a quick reference only. Real-world voltage drop can vary with installation conditions, temperature, and local code requirements.
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Planning and safety note
This content is for general learning and planning. Always verify work against current NEC requirements, manufacturer instructions, and local code rules. If you are unsure or see heat, sparks, burning smell, repeated trips, or damaged wiring, contact a licensed electrician.