Voltage Drop Calculator
Estimate DC/single-phase voltage drop for copper or aluminum.
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Tool
Circuit parameters
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Conductor material
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About the voltage drop calculator
Estimate conductor voltage drop for a DC or single-phase circuit using the approximate-resistance formula VD = 2 · K · I · L / CM.
How it works
Load current, one-way run length, wire AWG size, and conductor material feed into the classic K-factor method. The factor of 2 accounts for the out-and-back conductor path. Source voltage is used only to express drop as a percentage.
Wire sizes
AWG sizes come from the built-in reference table (4/0 through 40 AWG). Reference ampacity values shown in the dropdown are typical NEC Table 310.16-style figures for copper — not a code determination on their own.
Limitations
This is a simplified DC-resistance approximation. It ignores conductor temperature rise, AC skin and proximity effects, and reactance. Three-phase circuits use a different multiplier (√3, not 2) and are out of scope. It is not a substitute for an NEC Chapter 9 voltage-drop study or a licensed electrician's calculation.
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All calculations run locally in your browser. Nothing you type is sent to a Dockzio server.
FAQ
Quick answers to common questions.