buncha/engineering/voltagedrop

Voltage Drop Calculator

Wire size

Load amps

One-way distance (ft)

Source volts

Pass/fail target %

Phase

Conductor material

Voltage drop

4.14%

(4.97 V)

Over 3% target — but under 5%

End-of-run volts

115.03 V

Round-trip

200 ft

Wire

10 AWG

Material

Cu

Fix it by: upsizing the wire, shortening the run, switching from aluminum to copper, or boosting source voltage. Try the Wire Size Calculator for the smallest size that meets a target.

How it's computed. VD = (factor × K × I × L) / cm. Factor = 2 for single-phase, sqrt(3) for 3-phase. K = 12.9 (Cu) or 21.2 (Al). Circular-mil figures from NEC chapter 9 / Table 8. NEC informational note recommends ≤ 3% on branch circuits and ≤ 2% on feeders, with the combined feeder + branch not exceeding 5%.

Read the guide

Voltage Drop on Long Runs — When 12 AWG Isn't Enough

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About Voltage Drop Calculator

How much voltage do you lose over the run? Drop in volts, drop %, end-of-run voltage, and a pass/fail vs 3%.

Like every tool on Buncha, this one runs entirely in your browser. There's no upload, no log, no record of what you've pasted or generated. Close the tab and the data is gone.

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