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%.

Pairs well with

Board Feet Calculator

Lumber math by board feet — qty × thickness × widt…

Circuit Load Calculator

Add appliances → get the right breaker and wire si…

CNC Feeds & Speeds

RPM + IPM calculator for milling, drilling, and tu…

Conduit Fill Calculator

Will the bundle fit? NEC Chapter 9 fill % for EMT,…

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%.

Everything happens on your device. Close the tab and it's gone.