12 Volt Wire Size Calculator

Created by Arturo Barrantes
Reviewed by Wojciech Sas, PhD
Last updated: Oct 11, 2022

The 12 volt wire size calculator will help you determine the appropriate electrical wire for your next house installation. Do you want to install a new camera, maybe a new motion-sensing light? Please keep reading to determine how to size your cables.

How to calculate the size of a 12 volt wire?

We will use the resistivity concept and combine it with the ohm's law for a single conductor:

A=2×IϱLV×%drop,\quad A = \frac{2\times I \varrho L}{V \times \%\text{drop}},

where:

  • %drop\%\text{drop} — Allowable voltage drop, in %.
  • VV — Source voltage, measured in volts.
  • II — Maximum current running through the wire, measured in amps;
  • ϱ\varrho — Resistivity of the conductor material, measured in ohm meters;
  • LL — Length of the wire, measured in meters; and
  • AA — Cross-sectional area of the wire measured in square meters.

We add factor 2 because we have a one-way from the source to the equipment and another one-way from the equipment to the source.

How do you use this 12 V wire size calculator?

You need to verify that your equipment can withstand 12 volts. Then you follow these steps:

  1. 12-volt ac / dc is already set. Now, we have to define the allowable voltage drop.
  2. Indicate the one-way length of your electrical system.
  3. Define how much current (amperes) your equipment needs.
  4. Finally, specify the maximum operating temperature.

Our 12 V wire size calculator will indicate the cross-sectional area, cable diameter, and AWG size.

Other useful tools like the 12 volt wire size calculator

Since you already know how to size a 12 volts wire, you can take a look at other calculators:

FAQ

Which size wire is recommended for 12 volts appliances?

You have to define the amperes your equipment needs as it directly impacts the 12-volt wire size calculation. However, if we:

  1. Add five amps into the OmniCalculator 12 volt wire size.
  2. Include the allowable voltage drop (maximum 5% for DC appliances).
  3. Finally, add the one-way length of our system (here we assume 7 m), and the max operating temperature; then, we get a 13 AWG wire.

Can I use 16 AWG wire for 12 volts applications?

It will depend on the maximum current you will have in the conductor. The OmniCalculator 12 volt wire size can help you:

  1. Add the maximum wire area corresponding to 16 AWG: 1.308 mm².
  2. Set the maximum operating temperature. By default, 50°C.
  3. Define the one-way distance (5 meters) and the maximum allowable voltage drop (3%). As a result, the maximum current is 2.5 amperes.

How many amps can a 14 AWG wire withstand on a 12-volts system?

3.97 amperes as per OmniCalculator's 12-volt wire size tool. For getting such a result, we need:

  1. Add the wire area corresponding to 14 AWG: 2.08 mm².
  2. Add a one-way distance of 5 meters.
  3. Include an allowable voltage drop of 3%.
  4. Define a maximum operating temperature of 50°C.
Arturo Barrantes
Allowable voltage drop (V)
%
Conductor material
Copper
Current (I)
A
One-way distance (L)
ft
Maximum wire temperature
°F
Recommended wire size
Wire cross-sectional area (A)
kcmil
Wire gauge
AWG
Wire diameter (d)
in
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