Voltage Drop Calculator

Inputs

Circuit type

Single-phase/DC uses a two-conductor path. Three-phase uses the balanced line-to-line shortcut.

Conductor material

Uses 75 C resistance constants: copper K=12.9, aluminum K=21.2 ohm-cmil/ft.

Wire size

Conductor circular-mil area used for voltage drop. This is not an ampacity selection.

One-way length (L)

One-way distance from source to load, not round-trip length.

Load current (I)

Load current in amperes.

System voltage (V)

Line-to-line voltage for three-phase, or source voltage for single-phase/DC.

Target max drop (%)

Used for the max-length and suggested-area outputs. Common design screens use 3% for branch or feeder and 5% total.

Default result

Voltage drop(VD)

2.63%

Pass

At or below the 3% target.

Also computed

Voltage lost(V_drop)3.161V

Load-end voltage(V_load)116.84V

Max one-way length(L_max)17.36m

For the selected wire and target percent drop.

Suggested conductor area(CM_min)6.53kcmil

nearest listed size: #12 AWG

Selected conductor area(CM)6.53kcmil

#12 AWG

One-way conductor resistance(R)0.09877ohm

Method notes 2 notes

single-phase shortcut using copper conductor constant and one-way length.
This screens voltage drop only. It does not check ampacity, insulation temperature, conduit fill, derating, equipment grounding conductors, termination ratings or local code requirements.