Wire diameter gauge (AWG) to mm & inches

Wires are the basic component of every DIY electrical installation. They’re used for almost everything electricity-related. In most modern homes, they’re abundant. Being able to assemble and use those installations is one thing.


Wire diameter gauges is denoted in AWG which can be translated to either mm or inches. Using AWG to denote gauge ensures a comprehensible industry standard you can rely on.

From the chart below, the following can be seen.

  • 0 AWG has a diameter of 0.825 cm or 8.251 mm.
  • 2 AWG has a diameter of 0.654 cm or 6.544 mm.
  • 4 AWG has a diameter of 0.519 cm or 5.189 mm.

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However, picking the right components in the first place is something completely different. The wire’s size is an element that’s not taught anywhere and needs to be learned individually.

It’s a surprisingly unknown component, considering its usefulness for everyday fixes and house improvements. Luckily, we’re here to help you.

In this article, you’ll learn about wire sizes, their characteristics, differences, and what an AWG metric is. Keep reading, and be ready to get some knowledge wired into you!

Wire diameter gauge chart (AWG) to mm, cm, & inches

Wire Number (Gauge)Metric Diameter (CM)Metric Diameter (MM)AWG or B&S Wire Diameter (Inches)
0000000 (7/0)1.65416.540.651300
000000 (6/0)1.47314.730.580049
00000 (5/0)1.31213.120.516549
0000 (4/0)1.16811.680.460000
000 (3/0)1.04010.400.409642
00 (2/0)0.9279.2660.364797
0 (1/0)0.8258.2510.324861
10 awg wire

How do the sizes work?

AWG is the normal way of describing wire size in North America. First introduced in 1857, this standardized method was introduced as a replacement for all the different denotations that different wire companies used.

It determines the diameter of the wire, similarly to how SWG (Standard Wire Gauge) does in Britain. It’s a bit counterintuitive as it uses progressively bigger numbers to denote progressively smaller wire diameter sizes.

Thus, the bigger the number is, the thinner the wire will be. The sizes range from 0000 AWG to 40 AWG. Some smaller or bigger sizes might exist, but they’re not normalized as they’re rarely used. 

AWG only determines a wire’s size, which means it excludes the insulation surrounding it. There’s a detailed description of what wires can be labeled using AWG- they need to be single strands of round, solid, electrically conductive wire.

Everything else that derives from these characteristics cannot be denoted with AWG denotations.

10 & 12 awg stranded thhn

Although sizes attached to different AWG denotations might look random initially, they’re all mathematically determined.

They work because two sizes are used as a “base”- the biggest and the smallest. The biggest one, 0000 AWG, means 0.46 inches in diameter, while 36 AWG is described as 0.005 inches in diameter.

Every other size is simply a logarithmic step between those two. With 39 in-between sizes existing and the diameter ratio 1 to 92, every step is the 39th root of 92.

In plain terms, that contributes to about 1.12293x change in width from step to step.

Conversion from MM to gauge isn’t difficult, and the same goes for the opposite. You just have to know how to do it and have a calculator on your hands (or simply use the table we’ve provided)

300' AWG 10-2 Underground Wire

What does it stand for?

AWG is short for American Wire Gauge. It’s named this way because of the area it’s used in North America. Most other countries, for example, European countries use a global labeling norm of wire cross-section put in millimeters squared (mm2).

Despite the two labeling forms being largely different, they can be easily converted into each other. It allows for easy technical communication and the ability to buy items from the entire world. 

AWG vs. gauge

While the terms AWG and Gauge are being used heavily, the term AWG is technically correct. It is the term you’ll see on every technical documentation and every purchase offer for such items.

On the other hand, the gauge is a much more informal term. It’s used amongst technicians and electricians for simplicity and ease. Many informative articles, such as this one, use the label Gauge because it’s simpler and easier to understand.

When it comes to actual differences- there are none. These terms mean exactly the same thing. In everyday conversations, they can be used interchangeably.

Wire vs. Cable

Another term-related issue that many people have when it comes to electricity is the terminology of “cable” vs. “wire.” Many people use these terms interchangeably, especially those with no technical backgrounds.

For the most part, they’re not THAT wrong. Even though we can mean one or the other in most cases, they are NOT the same thing. There will be specific instances where labeling them wrong might lead to a serious miscommunication issue. 

A wire is a single strand of a relatively thin, conductive metal. On the other hand, a cable is the final installation composed of multiple wires stranded together and the insulation that coils around them.

If you’re just a regular person plugging anything into the electrical socket, you’re using a cable. If an electrician is performing a fix in your electrical installation, or if there’s a fundamental issue with a circuit in you’re house, they or you will be working with wires.

This distinction is important for two main reasons:

  1. Casual-to-technical conversations. Whenever you describe a problem to an electrician or whenever you’re speaking with a consultant, describing wires as cables or vice versa might lead to miscommunication. In turn, it can make you waste time or money.
  2. Safety issues: Drastically different measures have to be taken when working with one or the other. Using and fixing cables is pretty easy and can be done by casuals. Usually, a piece of insulation needs to be reapplied here and there, or maybe the cable’s twisted badly. You don’t need any safety equipment or measures to deal with it. On the other hand, wires require extreme caution. It’s because they’re a direct conductor of dangerous amounts of current. It’s best not to touch wires directly if you’re not a professional. If you have to, be extremely cautious and be thoroughly prepared. 

Even with all of this, it’s safe to say you’ll be able to use both terms as one in most everyday cases. It won’t create any confusion. The matter appears only if you’re dealing with specifics.

AWG wire

Dangers of choosing the wrong one

As we’ve already established, there are many different sizes. They range anywhere from 1,6CM in width all the way down to fractions of a centimeter. But why are there different sizes in the first place? And why should we worry about choosing the right one?

To answer the first question: Wires are conductive elements, and their physical attributes determine their electrical abilities. Namely, their diameter size is crucial to how much electrical current they can withhold before they overheat and are destroyed.

They also have different resistances, although this parameter is held at the lowest possible values in all types of wires. It’s done to prevent the current distortion in working circuits and not include the wires in the preparational calculations.

In short, the smaller the diameter, the bigger the resistance. Smaller wires will distort the entering current more than the larger ones. 

6 awg wire

The answer to the second question is closely tied to the first one. Because of the different models and their conductive characteristics, different circuits and machines use different current and wire sizes.

Some machines work with a much bigger current than others, such as electric stoves and furnaces. In contrast, other circuits require smaller currents, such as low-voltage lighting bulbs. Picking the right wire size is important because it will assure you that you’ll be able to use the wires safely.

Choosing the wrong wire size might resultin the machine or circuit not working properly in the best case scenario. It can be burning and fusing from too much current or lack of action from too little current.

In the worst case scenario, it can lead to various injuries due to electrical flow passing through your body. 

How to choose the right one

10 AWG Stranded THHN Green Wire

Choosing the right electrical wire size is not as hard as it may seem, contrary to what was written in the previous section of this article. See, it all comes down to knowing a few basics. Once you know the needed info, you’ll surely pick the right option. 

The main parameter that you need to check before picking your wires is how much current you’ll be using.

Although it’s not popular for regular people to perform changes/fixes to the appliances in their house that use high amperage (heaters, ovens, washing machines), it’s not impossible.

The common scenario is people looking to add fancy lighting to their house or perhaps install some remote control mechanisms. That’s why you’ll most likely be working with lower current values and need smaller wires.

In every case, take note of the technical documentation provided with it for every used machine or part. It will guide you through everything you need to know about the item. From amperage to sustained current and voltage values to recommended sizes etc. 

Make sure not to dispose of the documentation! 

#4 awg THHN copper wire

Electrical safety tips

Once you’ve bought your wires, it’s finally time to assemble some circuits. You have to be careful here. As we’ve previously established, electricity can be dangerous if it’s not used properly.

To ensure your safety during electrical work around your house, here are some safety tips you should follow:

  1. Turn the fuses off: Your house should have the main fuse box containing all the main fuses. Make sure to turn them all off, cutting off the electricity to the circuit parts you’ll be working on. If you’re unsure which fuse is responsible for which part of your house, turn them all off. You’ll be fine with no electricity for a while. For good measure, try to turn the lights on or look inside the fridge to make sure that the fuses are blocking the current.
  2. Check for static electricity. There can be multiple reasons for electricity to be present in circuits even after blocking them with fuses. For this reason, grab a sampler screwdriver (a little screwdriver used for checking electricity) and touch the wire with it. If the screwdriver detects ANY electricity, DO NOT touch the wire or attempt to work on it. 
  3. Equip yourself with isolation tape and wire isolation. After you work on the cables, make sure to isolate them properly. Every single strand should be kept separate (except for multi-strand wires). Remember- it’s better to use too much isolation than to use too little. 
  4. If you’re unsure whether you’re doing something right, don’t do it at all. Live electricity is nothing to be played with. You should assess your capabilities realistically and not cross them so as not to mess something up that can harm you. If you can’t do something with 100% certainty, ask a professional to do it for you.
  5. Keep any fluids away from wires: You should ensure that all liquids are not anywhere near the place you’re performing your task, especially conductive ones such as water. It poses a hazard of electricity spreading through the liquid and harming you or other machines in your house. 
  6. Perform thorough observations after: When you’re done with your fixes, observe and monitor how the fixed circuit is working. Do this for a while to ensure everything is alright, and only then can you count the job as successful. 
500 Ft General Wire 10 Awg

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