Engineering Reference
AWG, Metric Wire Size and Circular Mils Reference
AWG lookup tables and definitions for solid-wire diameter, metric cross-sectional area, circular mils, kcmil, gauge notation, and geometry conversion boundaries.
- Reading Time
- 13 min
- AWG Range
- 4/0 to AWG 40
- Updated
- September 27, 2026
AWG Diameter and Area Lookup
Values are formula-derived bare solid-conductor geometry. Display rounding does not replace the full-precision shared data used by calculators.
| Gauge | Diameter mm | Diameter mil | Area mm² | Circular mil | kcmil |
|---|---|---|---|---|---|
| 4/0 | 11.6840 | 460.000 | 107.2193 | 211600 | 211.6000 |
| 3/0 | 10.4049 | 409.642 | 85.0288 | 167806 | 167.8064 |
| 2/0 | 9.2658 | 364.797 | 67.4309 | 133077 | 133.0765 |
| 1/0 | 8.2515 | 324.861 | 53.4751 | 105535 | 105.5345 |
| AWG 2 | 6.5437 | 257.626 | 33.6308 | 66371 | 66.3713 |
| AWG 4 | 5.1894 | 204.307 | 21.1506 | 41741 | 41.7413 |
| AWG 6 | 4.1154 | 162.023 | 13.3018 | 26251 | 26.2514 |
| AWG 8 | 3.2636 | 128.490 | 8.3656 | 16510 | 16.5097 |
| AWG 10 | 2.5882 | 101.897 | 5.2612 | 10383 | 10.3830 |
| AWG 12 | 2.0525 | 80.808 | 3.3088 | 6530 | 6.5299 |
| AWG 14 | 1.6277 | 64.084 | 2.0809 | 4107 | 4.1067 |
| AWG 16 | 1.2908 | 50.821 | 1.3087 | 2583 | 2.5827 |
| AWG 18 | 1.0237 | 40.303 | 0.8230 | 1624 | 1.6243 |
| AWG 20 | 0.8118 | 31.961 | 0.5176 | 1022 | 1.0215 |
| AWG 22 | 0.6438 | 25.347 | 0.3255 | 642 | 0.6424 |
| AWG 24 | 0.5106 | 20.101 | 0.2047 | 404 | 0.4040 |
| AWG 26 | 0.4049 | 15.941 | 0.1288 | 254 | 0.2541 |
| AWG 28 | 0.3211 | 12.641 | 0.0810 | 160 | 0.1598 |
| AWG 30 | 0.2546 | 10.025 | 0.0509 | 101 | 0.1005 |
| AWG 32 | 0.2019 | 7.950 | 0.0320 | 63 | 0.0632 |
| AWG 34 | 0.1601 | 6.305 | 0.0201 | 40 | 0.0398 |
| AWG 36 | 0.1270 | 5.000 | 0.0127 | 25 | 0.0250 |
| AWG 38 | 0.1007 | 3.965 | 0.0080 | 16 | 0.0157 |
| AWG 40 | 0.0799 | 3.145 | 0.0050 | 10 | 0.0099 |
Geometry and Gauge Relationships
| Quantity | Relationship | Boundary |
|---|---|---|
| AWG diameter | d(in) = 0.005 × 92^((36 − AWG)/39) | Formula for AWG solid-conductor nominal diameter |
| Metric area | A = πd²/4 | Round solid metallic conductor |
| Mil | 1 mil = 0.001 in = 0.0254 mm | Diameter unit, not area |
| Circular mil | cmil = d(mil)² | Defined circular-area unit |
| kcmil | 1 kcmil = 1000 cmil | Large conductor area |
| Area conversion | 1 cmil = π/4 × (0.001 in)² | Converts circular mil to ordinary square area |
| Gauge step | Six AWG steps double diameter approximately | Area changes by about four times |
| Stranded area | Ametal = Σ(πdstrand²/4) | Overall bundle diameter also depends on lay and packing |
Common Cross-Checks
| Reference | Approximate value | Use |
|---|---|---|
| AWG 10 | 2.588 mm diameter; 5.261 mm² | Common geometry anchor |
| AWG 12 | 2.053 mm diameter; 3.309 mm² | Compare with nearby metric preferred sizes |
| AWG 18 | 1.024 mm diameter; 0.823 mm² | Harness and low-power geometry anchor |
| AWG 24 | 0.511 mm diameter; 0.205 mm² | Signal-wire geometry anchor |
| AWG 30 | 0.255 mm diameter; 0.0509 mm² | Fine-wire geometry anchor |
| 1 mm² | ≈1973.5 cmil | Area conversion only; not an AWG designation |
Common Wire-Size Mistakes
- Assuming a larger AWG number means a larger conductor.
- Treating an AWG-to-mm² conversion as a preferred metric size designation.
- Confusing diameter in mils with area in circular mils.
- Using kcmil as a diameter unit.
- Using bare solid diameter as insulated cable outside diameter.
- Treating stranded bundle diameter as equivalent solid diameter.
- Confusing AWG with SWG or another gauge system.
- Rounding diameter before calculating area.
- Using conductor area alone to claim ampacity.
- Ignoring material when estimating resistance or mass.
- Ignoring installation and temperature limits.
- Using display-rounded table values for precision round trips.
Support reference
FAQ
What does AWG mean?
American Wire Gauge is a logarithmic solid-conductor diameter system. Larger gauge numbers represent smaller diameters.
Why does a lower AWG number mean a larger wire?
The historical gauge sequence is inverse: each step toward a smaller number increases diameter by a fixed geometric ratio.
What are 1/0, 2/0, 3/0, and 4/0 AWG?
They are progressively larger sizes below AWG 1, also written 0, 00, 000, and 0000.
Is AWG area the same as metric nominal wire size?
No. An AWG cross-sectional area can be converted to mm², but standard metric nominal sizes are separate preferred values.
What is a circular mil?
A circular mil is the area of a circle one mil in diameter. Numerically, circular-mil area equals diameter in mils squared.
What is kcmil?
One kcmil is 1000 circular mils. It is commonly used for large conductor areas.
Does strand count change conductor area?
A stranded conductor's metallic area is the sum of strand areas. Its overall outside diameter is larger because strands do not pack without voids and insulation adds thickness.
Can wire diameter determine ampacity?
No. Ampacity depends on material, insulation, temperature rating, installation, bundling, airflow, allowable rise, and applicable rules.
Does this table include insulation diameter?
No. The values describe ideal bare-conductor geometry; insulation and construction dimensions come from the cable datasheet.
Are AWG and SWG interchangeable?
No. American Wire Gauge and Standard Wire Gauge use different diameter sequences.
How is area calculated from diameter?
For a round solid conductor, A = πd²/4. Circular-mil area uses d² when d is expressed in mils.
Why can published AWG tables differ slightly?
Exact formula values may be rounded to different decimal places, and stranded or finished-wire dimensions may be mistaken for bare solid-conductor diameter.
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