Calcs4All

APR 23 · 2026

Wire gauge calculator

Screen AWG sizes against a target voltage-drop percentage.

What this calculator covers

Use this calculator to compare common AWG sizes against a voltage-drop target before you look deeper at code and installation constraints.

The result is a sizing screen, not a final conductor selection. Ampacity tables, insulation temperature, bundling, terminals, and local code rules still need to be checked separately.

Frequently asked questions

What voltage drop percentage should I target?
A common guideline for branch circuits is 3% or less, with a total of no more than 5% from the service panel to the furthest outlet when feeder drop is included. These are widely referenced planning values, but the applicable standard or code for your installation should take precedence.
Which AWG sizes does the calculator evaluate?
The calculator screens conductors from 14 AWG through 1/0 AWG and recommends the smallest listed size that keeps the drop within your target. If no size in that range meets the target, the result is flagged as a table-limit recommendation.
Does the calculator cover three-phase circuits?
No. It uses a single-phase two-conductor voltage drop formula. Three-phase feeders use a different factor and would need separate calculations.
Can I use this result to select the final wire size for an installation?
No. This is a voltage-drop screening tool only. Ampacity limits, temperature ratings, conduit fill, bundling derating, and local electrical code requirements must all be checked before selecting a conductor for actual installation. A licensed electrician should verify the final selection.

Tool

Run the calculation

A
ft
%

RESULT · RECOMMENDED AWG

â„–195

Primary result

10 AWG

10 AWG is the smallest listed conductor that keeps the drop to 2.4855 V, or 2.07%, within the 3.00% target.

Recommended gauge
10 AWG
Estimated drop
2.4855 V (2.07%)
Target maximum drop
3.6 V
Conductor material
copper

Step-by-step solution

  1. 1.Convert the percent-drop target into a voltage threshold: 120 V x 3.00% = 3.6 V.
  2. 2.Walk the AWG table from 14 AWG toward larger conductors, applying Vdrop = 2 x K x I x L / cmil for each candidate.
  3. 3.Stop at the first gauge that meets the target; that keeps the wire as small as possible while staying inside the requested drop limit.

Walkthrough

Visual walkthrough

Wire sizing here is a voltage-drop screen: start with a drop target, test each listed AWG, and choose the smallest size that passes.

  1. 01

    Set the drop budget

    120 V x 3.00%

    A percent-drop target becomes an absolute voltage budget before any wire is tested.

  2. 02

    Test each AWG option

    Vdrop = 2 x K x I x L / cmil

    Each candidate wire gets the same load, length, and material inputs so only conductor area changes.

  3. 03

    Choose the first passing gauge

    The first passing entry in the ordered table is the smallest listed conductor that still meets the drop target.

    10 AWG