AWG Wire Size Converter
Convert AWG wire gauge to millimetres, inches and circular mils from the standard table.
What this tool does
An AWG wire size converter translates American Wire Gauge numbers into physical dimensions: AWG 12 is 2.05 mm, AWG 14 is 1.63 mm, AWG 10 is 2.59 mm. The scale runs backwards from intuition - a lower gauge number means a thicker wire, and every three gauge steps double the cross-section. The converter reads the standard table rather than approximating, and returns millimetres, inches and circular mils together, because different wire standards quote different units.
Converts AWG to millimetre and back from the standard gauge table, not a formula approximation.
Shows inches, millimetres and circular mils together for each gauge.
Notes that a lower AWG number means a thicker wire, which the scale's direction confuses.
Covers the solid-conductor table from AWG 40 up to 4/0 power sizes.
How to use it
- Enter the AWG gauge number, or use the stepper to walk the scale.
- Read the diameter in millimetres and inches.
- Check the cross-section in square millimetres and circular mils.
- Compare against the current-carrying context before sizing a circuit.
Why use this calculator
Converting AWG to millimetres is the first step in matching a wire spec to a standard: US cable is sold in gauge numbers while most of the world uses millimetre diameters, and the relationship is neither linear nor obvious. Worse, the scale runs the opposite way to what most people expect - AWG 10 is thicker than AWG 14 - so a conversion done from memory regularly produces wire that is dangerously undersized for the current it must carry.
Why we built it
We built the AWG wire size converter to read the standard table instead of computing from the formula, because the table is what standards bodies publish and what cable is actually marked. The wire size calculator picks the gauge from current and run length, the voltage drop calculator checks the run against the drop limit, and the millimetres to inches converter handles the plain unit translation without the gauge scale.
For the current itself, the amps to watts converter and the watts to amps converter translate the load, and the length converter handles the run in either unit.
Who this tool is for
- Electricians and apprentices reading US cable specifications
- Anyone importing or fitting US-standard wire
- Electronics hobbyists choosing hook-up wire
- Engineers converting a gauge spec for metric procurement
When to use it
- Reading a US cable spec that quotes gauge only.
- Checking whether a wire is thick enough for a known current.
- Converting a metric diameter requirement into a gauge.
- Comparing stranded and solid conductor sizes.
How it is calculated
The AWG scale is defined so that each gauge step changes the diameter by a factor of the 39th root of 92, about 1.123. Diameter = 0.127 × 92^((36 − AWG) ÷ 39) mm. Every three gauge steps double the cross-sectional area: AWG 14 is 2.05 mm², AWG 11 is 4.11 mm². Circular mils are the square of the diameter in mils (thousandths of an inch).
Worked example: AWG 12 is 2.053 mm in diameter, 0.0808 inches, 3.31 mm² cross-section and 6,530 circular mils - the standard 20 A lighting circuit wire in the US. AWG 14, one step thinner, drops to 2.08 mm² and a 15 A class.
The table gives bare solid conductor diameter. Stranded cable of the same gauge has the same conductor cross-section but a larger overall diameter, and insulation adds more still. For conduit fill and cable trays, use the overall diameter, not the conductor figure.
The common gauges
| AWG | Diameter (mm) | Diameter (in) | Area (mm²) | Typical use |
|---|---|---|---|---|
| 18 | 1.02 | 0.0403 | 0.82 | Lighting loops, low current |
| 16 | 1.29 | 0.0508 | 1.31 | Small appliances |
| 14 | 1.63 | 0.0641 | 2.08 | 15 A circuits |
| 12 | 2.05 | 0.0808 | 3.31 | 20 A outlets, AC units |
| 10 | 2.59 | 0.1019 | 5.26 | 30 A appliances |
| 8 | 3.26 | 0.1285 | 8.37 | Ranges, small sub-panels |
| 6 | 4.11 | 0.1620 | 13.3 | Water heaters, dryers |
A worked example
These are the values the calculator opens with, so you can see exactly what it does with them. Change the gauge on the page and the result updates; the figures below come from the same table.
| Input | Value |
|---|---|
| Gauge | AWG 12 |
| Conductor | Solid |
With those inputs, the calculator returns:
- Diameter: 2.053 mm (0.0808 in)
- Cross-section: 3.31 mm²
- Circular mils: 6,530 cmil
- Context: the standard 20 A circuit wire
Which direction does the scale run?
| Gauge | Compared with the next | Cross-section |
|---|---|---|
| AWG 40 | Finest in the table | 0.00013 mm² |
| AWG 30 | Thin, electronics wire | 0.051 mm² |
| AWG 20 | Hook-up wire | 0.52 mm² |
| AWG 10 | Power appliance wire | 5.26 mm² |
| AWG 4/0 | Thickest common size | 107 mm² |
Lower number, thicker wire - the scale counts how many times the wire has been drawn down. The one exception to remember is that 00, 000 and 0000 (written 2/0, 3/0, 4/0) come after AWG 1 and are thicker still.
What you enter, and what you get back
| Item | Details |
|---|---|
| Gauge | AWG number from 40 up to 4/0. |
| Result | Diameter in mm and inches, area in mm² and circular mils. |
| Context | The typical current class and use for that gauge. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Wire seems backwards | Lower number assumed to mean thinner. | Lower AWG is thicker - check the mm figure. |
| Metric cable in an AWG spec | mm² area quoted, not diameter. | Match the cross-section, not the diameter. |
| Stranded cable feels larger | Strands braid wider than one solid core. | Compare conductor area; ignore overall diameter. |
| SWG or AWG confusion | Two different gauge standards. | SWG is British and follows a separate table. |
Assumptions and limitations
- Table figures are for bare solid conductors; stranded and insulated cable is larger overall.
- Current ratings depend on insulation temperature, bundling and ambient heat - the table is a size reference only.
- SWG and other national gauge standards use different tables.
- For circuit sizing, use the wire size calculator with the actual current and run length.
Frequently asked questions
What size wire is AWG 12 in mm?
AWG 12 is 2.053 mm in diameter, with a cross-section of 3.31 mm². It is the standard wire for 20 A circuits in the US, equivalent to roughly 2.5 mm² cable in metric markets. Stranded cable of the same gauge has the same conductor area but a larger overall diameter.
How do I convert AWG to millimetres?
Use the gauge formula: diameter = 0.127 × 92^((36 − AWG) ÷ 39) mm, or read the standard table. AWG 14 is 1.63 mm, AWG 10 is 2.59 mm, AWG 8 is 3.26 mm. The calculator returns the exact table figure rather than an approximation.
What is the difference between AWG and SWG?
They are separate standards. AWG (American Wire Gauge) uses a defined mathematical scale; SWG (Standard Wire Gauge, British) follows a historical table, and the two give different diameters for the same number - AWG 20 is 0.812 mm while SWG 20 is 0.914 mm. Always state which scale a gauge figure uses.
Which AWG wire carries the most current?
The thickest wire carries the most: 4/0 AWG (107 mm²) handles well over 200 A, while AWG 14 handles about 15 A. Within a run, current capacity rises with cross-section - every three gauge steps double the area and roughly double the capacity.
How many amps can AWG 14 carry?
About 15 A in the typical US residential installation for copper conductors in cable, which is why AWG 14 is the standard lighting-circuit wire. Bundling, insulation temperature and ambient heat all reduce the figure, so local electrical codes govern the final rating.
Is a lower AWG number thicker?
Yes - the scale counts drawing steps, so a lower number means fewer reductions and a thicker conductor. AWG 10 is thicker than AWG 14, and past AWG 1 the sizes continue as 2/0, 3/0 and 4/0 (00, 000, 0000), thicker still.