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ToolsWire AWG Size Conversion Calculator Overview
The Wire AWG Size Conversion Calculator converts between American Wire Gauge, wire diameter, cross-sectional area, and circular mil area. It is useful when comparing wire sizes shown in AWG with metric values such as millimeters and square millimeters.
Enter a known value, such as AWG number, diameter, area in mm², or circular mil area, and the calculator displays the equivalent wire size values. These conversions are especially helpful when reading datasheets, choosing hookup wire, comparing US and metric wire sizes, or checking a cable drawing.
What Is AWG?
AWG means American Wire Gauge. It is a logarithmic wire-size system used mainly in North America for round electrical conductors. In AWG, a smaller gauge number means a larger wire. For example, 10 AWG is larger than 20 AWG.
Large sizes below 1 AWG are written as 0, 00, 000, and 0000, also called 1/0, 2/0, 3/0, and 4/0. The 4/0 size is larger than 3/0, 2/0, 1/0, and 1 AWG.
AWG Conversion Formulas
For gauge number n, the solid round conductor diameter is:
d(in) = 0.005 × 92^((36 - n) / 39)
d(mm) = 0.127 × 92^((36 - n) / 39)
The cross-sectional area is:
Area(mm²) = π × d(mm)² / 4
Circular mil area is:
CMA = (d(in) × 1000)²
| Term | Meaning | Typical Unit |
|---|---|---|
| AWG | American Wire Gauge size. | gauge number |
| d | Conductor diameter, not including insulation. | mm or inch |
| Area | Cross-sectional conductor area. | mm² |
| CMA | Circular mil area, where one circular mil is the area of a circle with a diameter of one mil. | circular mil |
AWG to Diameter and Area Table
| AWG | Diameter mm | Diameter inch | Area mm² | Circular Mil Area |
|---|---|---|---|---|
| 0000 (4/0) | 11.6840 | 0.4600 | 107.2193 | 211,600 |
| 000 (3/0) | 10.4049 | 0.4096 | 85.0288 | 167,806 |
| 00 (2/0) | 9.2658 | 0.3648 | 67.4309 | 133,077 |
| 0 (1/0) | 8.2515 | 0.3249 | 53.4751 | 105,535 |
| 1 | 7.3481 | 0.2893 | 42.4077 | 83,693 |
| 2 | 6.5437 | 0.2576 | 33.6308 | 66,371 |
| 3 | 5.8273 | 0.2294 | 26.6705 | 52,635 |
| 4 | 5.1894 | 0.2043 | 21.1506 | 41,741 |
| 5 | 4.6213 | 0.1819 | 16.7732 | 33,102 |
| 6 | 4.1154 | 0.1620 | 13.3018 | 26,251 |
| 7 | 3.6649 | 0.1443 | 10.5488 | 20,818 |
| 8 | 3.2636 | 0.1285 | 8.3656 | 16,510 |
| 9 | 2.9064 | 0.1144 | 6.6342 | 13,093 |
| 10 | 2.5882 | 0.1019 | 5.2612 | 10,383 |
| 11 | 2.3048 | 0.0907 | 4.1723 | 8,234 |
| 12 | 2.0525 | 0.0808 | 3.3088 | 6,530 |
| 13 | 1.8278 | 0.0720 | 2.6240 | 5,178 |
| 14 | 1.6277 | 0.0641 | 2.0809 | 4,107 |
| 15 | 1.4495 | 0.0571 | 1.6502 | 3,257 |
| 16 | 1.2908 | 0.0508 | 1.3087 | 2,583 |
| 17 | 1.1495 | 0.0453 | 1.0378 | 2,048 |
| 18 | 1.0237 | 0.0403 | 0.8230 | 1,624 |
| 19 | 0.9116 | 0.0359 | 0.6527 | 1,288 |
| 20 | 0.8118 | 0.0320 | 0.5176 | 1,022 |
| 21 | 0.7229 | 0.0285 | 0.4105 | 810 |
| 22 | 0.6438 | 0.0253 | 0.3255 | 642 |
| 23 | 0.5733 | 0.0226 | 0.2582 | 509 |
| 24 | 0.5106 | 0.0201 | 0.2047 | 404 |
| 25 | 0.4547 | 0.0179 | 0.1624 | 320 |
| 26 | 0.4049 | 0.0159 | 0.1288 | 254 |
| 27 | 0.3606 | 0.0142 | 0.1021 | 202 |
| 28 | 0.3211 | 0.0126 | 0.0810 | 160 |
| 29 | 0.2859 | 0.0113 | 0.0642 | 127 |
| 30 | 0.2546 | 0.0100 | 0.0509 | 101 |
| 31 | 0.2268 | 0.0089 | 0.0404 | 80 |
| 32 | 0.2019 | 0.0080 | 0.0320 | 63 |
| 33 | 0.1798 | 0.0071 | 0.0254 | 50 |
| 34 | 0.1601 | 0.0063 | 0.0201 | 40 |
| 35 | 0.1426 | 0.0056 | 0.0160 | 32 |
| 36 | 0.1270 | 0.0050 | 0.0127 | 25 |
| 37 | 0.1131 | 0.0045 | 0.0100 | 20 |
| 38 | 0.1007 | 0.0040 | 0.0080 | 16 |
| 39 | 0.0897 | 0.0035 | 0.0063 | 12 |
| 40 | 0.0799 | 0.0031 | 0.0050 | 10 |
How to Use the Calculator
Choose the value you already know, such as AWG number, conductor diameter, area in mm², or circular mil area. Enter the value and read the equivalent values in the other units. For common wire-selection work, use the calculated area as a comparison point, then confirm the actual cable specification from the manufacturer.
The table and formulas describe the bare conductor. They do not include insulation thickness, jacket diameter, strand construction, plating thickness, or manufacturing tolerance. A stranded cable with the same nominal conductor area can have a larger outside diameter than a solid conductor.
AWG and Metric Cable Size Are Not Always Exact Matches
AWG and metric cable sizes are based on different systems, so they rarely match exactly. For example, 12 AWG has a conductor area of about 3.31 mm², while common metric cable sizes jump from 2.5 mm² to 4 mm². In this case, either size might be wrong or right depending on current, voltage drop, installation method, insulation rating, temperature, and applicable electrical code.
Do not choose a cable size from area conversion alone for mains wiring, battery wiring, heaters, motors, or other high-current circuits. Use the relevant electrical code, product standard, current rating table, and manufacturer datasheet.
Solid Wire, Stranded Wire, and Cable Diameter
| Item | What It Means | Why It Matters |
|---|---|---|
| Solid conductor diameter | The diameter of one round conductor. | This is what the AWG formula directly calculates. |
| Stranded conductor area | The total metal area of all strands. | Stranding changes flexibility and outside diameter but not the nominal copper area. |
| Insulated wire diameter | The conductor plus insulation. | Needed for connector fit, conduit fill, cable gland sizing, and harness routing. |
| Cable outside diameter | The full finished cable diameter, including jacket and fillers. | Cannot be calculated from AWG alone; use the cable datasheet. |
Common Conversion Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming a larger AWG number means a larger wire. | AWG works the opposite way: smaller gauge number means larger conductor. |
| Using bare conductor diameter as finished cable diameter. | Add insulation and jacket dimensions from the manufacturer datasheet. |
| Choosing wire only by area conversion. | Also check ampacity, voltage drop, temperature rating, insulation type, and installation method. |
| Rounding down to the nearest metric size without checking current. | When safety or heat matters, use the governing code or choose the next suitable size. |
| Confusing circular mils with square mils. | Circular mil area is based on the square of diameter in mils, not a square side length. |
Where AWG Conversion Is Used
AWG conversion is useful in wiring harness design, PCB connector selection, crimp terminal selection, cable replacement, speaker cable comparison, low-voltage power wiring, prototyping, repair work, and cross-referencing US and metric datasheets.
For final engineering decisions, confirm the exact wire construction, insulation system, conductor material, temperature rating, voltage rating, flexibility, approvals, and installation requirements.
FAQ
Does AWG describe the conductor or the insulation?
AWG describes the conductor size. Insulation thickness and jacket diameter are separate cable construction details.
Why is 4/0 larger than 1/0?
The zero sizes continue the AWG scale below 1 AWG. More zeros mean a larger conductor, so 4/0 is larger than 3/0, 2/0, and 1/0.
Can I use this calculator for aluminum wire?
The geometric conversion works for any round conductor size, but electrical current rating and resistance depend on the conductor material. Aluminum and copper of the same size do not have the same resistance or ampacity.
Does the table give ampacity?
No. Ampacity depends on conductor material, insulation rating, ambient temperature, bundling, installation method, number of current-carrying conductors, and code requirements. Use an approved ampacity table for safety-critical wiring.
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