Electronics & Wiring
AWG to mm and inches (Wire Gauge Conversion)
AWG describes a nominal wire diameter using a logarithmic gauge scale. Diameter and cross-sectional area are geometric values, not allowable current ratings.
Maintained by mmtoinches.im · Updated
NIST describes the standard inch as exactly equivalent to 25.4 mm
. NIST length definition. NIST Handbook 100 — Copper wire tables. Method and limitations.
Convert American Wire Gauge (AWG) sizes to millimeters and inches. Use the quick table for common gauges, then verify strand diameter and ampacity with manufacturer specs.
Conversion formulas
AWG nominal diameter (in) = 0.005 × 92^((36 − AWG)/39)
mm = inches × 25.4
Cross-sectional area (mm²) = π × (dmm/2)²
Circular mils (CM) = (dinch × 1000)²; kcmil = CM / 1000
Use mm to inches and fraction converters for custom values; keep ampacity decisions tied to standards.
Quick tools
Convert arbitrary diameters with the main calculator. For fractional notation, use the fraction converter.
Interactive AWG calculator
Set gauge to see diameter, cross-sectional area, circular mils (CM/kcmil), and approximate copper DC resistance at 20°C.
AWG wire chart (0000–40)
AWG wire chart (0000–40)
Cable gauge AWG quick reference with diameter, area, circular mils, and approximate copper DC resistance at 20°C. Values are nominal for solid conductors.
| AWG | Diameter (mm) | Diameter (in) | Area (mm²) | CM | kcmil | Copper DC R @20°C (Ω/km) |
|---|---|---|---|---|---|---|
| 0000 (4/0) | 11.684 | 0.4600 | 107.219 | 211600 | 212 | 0.16 |
| 000 (3/0) | 10.405 | 0.4096 | 85.029 | 167806 | 168 | 0.20 |
| 00 (2/0) | 9.266 | 0.3648 | 67.431 | 133077 | 133 | 0.26 |
| 0 | 8.251 | 0.3249 | 53.475 | 105535 | 106 | 0.32 |
| 1 | 7.348 | 0.2893 | 42.408 | 83693 | 84 | 0.41 |
| 2 | 6.544 | 0.2576 | 33.631 | 66371 | 66 | 0.51 |
| 3 | 5.827 | 0.2294 | 26.670 | 52635 | 53 | 0.65 |
| 4 | 5.189 | 0.2043 | 21.151 | 41741 | 42 | 0.82 |
| 5 | 4.621 | 0.1819 | 16.773 | 33102 | 33 | 1.03 |
| 6 | 4.115 | 0.1620 | 13.302 | 26251 | 26 | 1.30 |
| 7 | 3.665 | 0.1443 | 10.549 | 20818 | 21 | 1.63 |
| 8 | 3.264 | 0.1285 | 8.366 | 16510 | 17 | 2.06 |
| 9 | 2.906 | 0.1144 | 6.634 | 13093 | 13 | 2.60 |
| 10 | 2.588 | 0.1019 | 5.261 | 10383 | 10 | 3.28 |
| 11 | 2.305 | 0.0907 | 4.172 | 8234 | 8 | 4.13 |
| 12 | 2.053 | 0.0808 | 3.309 | 6530 | 7 | 5.21 |
| 13 | 1.828 | 0.0720 | 2.624 | 5178 | 5 | 6.57 |
| 14 | 1.628 | 0.0641 | 2.081 | 4107 | 4 | 8.29 |
| 15 | 1.450 | 0.0571 | 1.650 | 3257 | 3 | 10.45 |
| 16 | 1.291 | 0.0508 | 1.309 | 2583 | 3 | 13.17 |
| 17 | 1.150 | 0.0453 | 1.038 | 2048 | 2 | 16.61 |
| 18 | 1.024 | 0.0403 | 0.823 | 1624 | 2 | 20.95 |
| 19 | 0.912 | 0.0359 | 0.653 | 1288 | 1 | 26.41 |
| 20 | 0.812 | 0.0320 | 0.518 | 1022 | 1 | 33.31 |
| 21 | 0.723 | 0.0285 | 0.410 | 810 | 1 | 42.00 |
| 22 | 0.644 | 0.0253 | 0.326 | 642 | 1 | 52.96 |
| 23 | 0.573 | 0.0226 | 0.258 | 509 | 1 | 66.78 |
| 24 | 0.511 | 0.0201 | 0.205 | 404 | 0 | 84.21 |
| 25 | 0.455 | 0.0179 | 0.162 | 320 | 0 | 106.19 |
| 26 | 0.405 | 0.0159 | 0.129 | 254 | 0 | 133.90 |
| 27 | 0.361 | 0.0142 | 0.102 | 202 | 0 | 168.85 |
| 28 | 0.321 | 0.0126 | 0.081 | 160 | 0 | 212.92 |
| 29 | 0.286 | 0.0113 | 0.064 | 127 | 0 | 268.48 |
| 30 | 0.255 | 0.0100 | 0.051 | 101 | 0 | 338.55 |
| 31 | 0.227 | 0.0089 | 0.040 | 80 | 0 | 426.90 |
| 32 | 0.202 | 0.0080 | 0.032 | 63 | 0 | 538.32 |
| 33 | 0.180 | 0.0071 | 0.025 | 50 | 0 | 678.80 |
| 34 | 0.160 | 0.0063 | 0.020 | 40 | 0 | 855.96 |
| 35 | 0.143 | 0.0056 | 0.016 | 32 | 0 | 1079.34 |
| 36 | 0.127 | 0.0050 | 0.013 | 25 | 0 | 1361.02 |
| 37 | 0.113 | 0.0045 | 0.010 | 20 | 0 | 1716.22 |
| 38 | 0.101 | 0.0040 | 0.008 | 16 | 0 | 2164.11 |
| 39 | 0.090 | 0.0035 | 0.006 | 12 | 0 | 2728.89 |
| 40 | 0.080 | 0.0031 | 0.005 | 10 | 0 | 3441.07 |
Disclaimer: Values are rounded and based on nominal solid conductor diameter. Stranded wire overall diameters vary by strand count and insulation. Resistance uses copper resistivity ≈ 1.724 µΩ·cm at 20°C (IACS 100%). Use manufacturer datasheets and standards (NEC/IEC) for ampacity.
Reference: American wire gauge, IACS copper. For background, see gauge systems explained.
Frequently Asked Questions
Stranded wire bundles multiple smaller conductors. The nominal AWG refers to the equivalent total cross-sectional area, but overall diameter can differ by strand count and insulation. Always check manufacturer data for stranded diameter.
No. Ampacity depends on insulation temperature rating, ambient temperature, bundling, installation method, and allowable voltage drop. Use ampacity charts from standards (e.g., NEC) for safe current limits.
AWG nominal diameter (in) = 0.005 × 92^((36 − AWG)/39). Multiply by 25.4 to get mm. Charts round values for readability.
In the US, 12 AWG copper is commonly used for 20A residential branch circuits when insulation and installation meet NEC requirements. Always verify local code, temperature rating (e.g., 60/75/90°C), bundling, and voltage drop; consult NEC tables.
Automotive wiring varies by load and length: high-current feeds may use 6–8 AWG; accessories often use 10–14 AWG; signals typically 18–22 AWG. Conditions (temperature, vibration), routing, and fuse ratings matter. Always check the vehicle manufacturer guidance and datasheets.
Solid Cat5e/Cat6 conductors are often 23–24 AWG; stranded patch cords may use 26–28 AWG for flexibility. Check the cable datasheet; PoE current, installation practice, and run length can affect performance and heating.
Convert and specify wire sizes
Pair nominal AWG dimensions with rounded mm and inch values on drawings, and reference ampacity tables for safe current ratings.
Sources and calculation notes
AWG describes a nominal wire diameter using a logarithmic gauge scale. Diameter and cross-sectional area are geometric values, not allowable current ratings.
Method: Nominal diameter in inches = 0.005 × 92^((36 − AWG) / 39). Multiply by 25.4 for mm; circular area = π × diameter² / 4. The historical NIST wire tables explain the AWG progression; resistance estimates use an ideal round copper conductor.
Scope: Insulation, conductor material, temperature and installation affect electrical suitability. Approximate copper resistance values are not a wiring design or ampacity recommendation.
Content maintained by mmtoinches.im. Updated and reference notes reviewed . How we calculate and present measurements. Sources support the stated definitions; examples and calculators are not certification of a product or compliance with a standard.