Battery Equivalents and Replacements

14 Gauge Wire Amps: How Thick is 14 Gauge Wire?

14 Gauge Wires are commonly used for powering devices that don't require too strong currents. Also, 14 gauge wires are sometimes used for wall power outlets but their Ampacity or current load carrying ability tells us that they should generally not be used for such purpose.

But, for many other applications, 14 gauge wires are the ideal thickness, due to their combination of thickness, price, and Ampacity.

Published: May 6, 2022.

14 wire gauge 1

14 Gauge Wire Thickness/Dimensions

AWG 14 wire or 14 gauge wire features physical dimensions of:

- diameter: 1.6277 mm, 0.0641 inches,

- cross-section area: 2.0809 mm2, 0.0032 inches2,

and these values are for solid 14 gauge wires, with 14 gauge stranded wires featuring somewhat different values (but very similar).

14 Gauge Wire Ampacity

The most important feature of any wire is its current load carrying ability (Ampacity) given in Amps at certain temperatures. The Ampacity of 14 gauge wires is:

- @60°C/140°F: 15 Amps,

- @75°C/167°F: 20 Amps,

- @90°C/194°F: 25 Amps.

As one can see, for most residential applications (@60°C/140°F), the Ampacity of 14 gauge wire is 15 Amps, while for other applications it "may" go up to 20 Amps. For the very limited number of applications and wires, the Ampacity of 14 gauge wires may go up to 25 Amps.

For more information about Ampacities of other wires sizes, feel free to check our AWG to mm2 Conversion Chart and Wire Sizes article.

However, these are just default values - for safety reasons, the 80% Rule is used, especially for residential applications. Thus, the actual Ampacity of 14 gauge wire is:

- @60°C/140°F: 15 Amps * 0.8 = 12 Amps

- @75°C/167°F: 20 Amps * 0.8 = 16 Amps

- @90°C/194°F: 25 Amps * 0.8 = 20 Amps

So, if You ever wondered should You use 14 gauge wire for wall power outlets, here is your answer - don't do it because the current carrying ability of 14 gauge wire of 12 Amps is not strong enough.

And this is without taking into account cable length.

When longer wires are used, the Ampacity decreases by 10% for every 50 feet (~15m) of the wire length.

For example, the actual Ampacity for a 150 feet long 14 gauge wire with the maximum allowed surface temperature of 60°F/140°F would be:

Ampacity = 15 * 0.8 / 1.3 = ~9.23 Amps

The following chart lists the Ampacity of 14 gauge wire at certain temperatures for the wires of 50, 100, 150, and 200 feet.

Wire Length / Temperature @60°C/140°F @75°C/167°F @90°C/194°F
Default 15 20 25
80% Rule 12 16 20
50 feet 10.9 14.5 18.1
100 feet 10 13.3 16.6
150 feet 9.2 12.3 15.3
200 feet 8.5 11.4 14.2

Note: the actual surface temperatures due to the current flowing through the wires will be lower, but to keep calculations simpler, maximum allowed currents are calculated using these formulas - remember that the actual goal is to keep energy losses low in longer cables AND to keep their maximum surface temperatures at the certain level.

How To Tell if The Wire is 12 or 14 Gauge?

The physical difference between 12 and 14 gauge wires is not large:

- 14 gauge wire diameter: 1.6277 mm, 0.0641 inches,

- 14 gauge cross-section area: 2.0809 mm2, 0.0032 inches2,

- 12 gauge wire diameter: 2.0525 mm, 0.0808 inches,

- 12 gauge cross-section area: 3.3088 mm2, 0.0051 inches2.

The easiest way of telling if the wire is 12 or 14 gauge is to read the labels on the insulation if they are present and visible.

If not, then one can "feel" the wires and tell which one is 12 and which one is 14 gauge. This is a very fast method, but not always accurate, which may lead to various issues later.

Perhaps the best method of checking if the wire is 12 or 14 gauge is to measure its diameter using a caliper - of all calipers, perhaps the digital calipers are the easiest to use.

14 Gauge Marine Wire

14 gauge marine wires feature Ampacity of other 14 gauge wires, but due to the marine applications, they feature better corrosion protection and often stronger mechanical insulation to additionally protect them from mechanical impacts and vibrations.

Because of these additional requirements, 14 gauge marine wire may be more expensive than ordinary 14 gauge wires.

However, if You have 14 gauge marine wire and You want to use them as ordinary 14 gauge wire, feel free to do so, just be sure not to do it another way around - don't use ordinary 14 gauge wire instead of 14 gauge marine wire.

14 gauge marine wire


Long Story Short: thicker wires can be harder to work with and they can lead to increased costs, but never use thinner wires than You should - energy losses and the surface temperatures can be simply too high.

Shorter 14 gauge wires are good for currents up to 12 Amps (after applying 80% Rule), but for stronger currents use thicker wires, for example, 12 gauge wire.

And whatever You do, stay safe - it is your own responsibility after all ... If unsure, contact a local certified electrician and let him/her do the work ...