AWG Wire Size Table
Enter an AWG number (1–40) or a zero-gauge (1/0, 2/0, 3/0, 4/0). Click a table row to populate this field.
Override the material preset with a specific resistivity value in Ω·m at 20°C.
Table Filters
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Enter an AWG Gauge to Begin
Type an AWG number (e.g. 12, 14, or 4/0) in the lookup field above, or click any row in the full reference table below to see complete wire specifications.
Wire Size Comparison (AWG 4/0 through AWG 15)
Bar width is proportional to wire diameter. Selected gauge highlighted.
−6 AWG = ×2 diameter
Every 6 gauge steps doubles diameter
−3 AWG = ×2 area
Every 3 gauge steps doubles area
−10 AWG = ÷10 resistance
Every 10 gauge steps divides resistance by 10
Complete AWG Reference Table
44 gauges shown| AWG | Diam (in) | Diam (mm) | kcmil | mm² | R (Ω/kft) | R (Ω/km) | Amps Chassis | Amps PowerTx | NEC 60°C | NEC 75°C | NEC 90°C | Al 75°C |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4/0 | 0.46000 | 11.684 | 211.6 | 107.2 | 0.0490 | 0.1608 | 380 | 302.3 | 195 | 230 | 260 | 180 |
| 3/0 | 0.40964 | 10.405 | 167.8 | 85.03 | 0.0618 | 0.2028 | 328 | 239.7 | 165 | 200 | 225 | 155 |
| 2/0 | 0.36480 | 9.266 | 133.1 | 67.43 | 0.0779 | 0.2557 | 283 | 190.1 | 145 | 175 | 195 | 135 |
| 1/0 | 0.32486 | 8.251 | 105.5 | 53.48 | 0.0983 | 0.3224 | 245 | 150.8 | 125 | 150 | 170 | 120 |
| 1 | 0.28930 | 7.348 | 83.69 | 42.41 | 0.1239 | 0.4065 | 211 | 119.6 | 110 | 130 | 150 | 100 |
| 2 | 0.25763 | 6.544 | 66.37 | 33.63 | 0.1562 | 0.5126 | 181 | 94.8 | 95 | 115 | 130 | 90 |
| 3 | 0.22942 | 5.827 | 52.63 | 26.67 | 0.1970 | 0.6464 | 158 | 75.2 | 85 | 100 | 110 | 75 |
| 4 | 0.20431 | 5.189 | 41.74 | 21.15 | 0.2484 | 0.8151 | 135 | 59.6 | 70 | 85 | 95 | 65 |
| 5 | 0.18194 | 4.621 | 33.10 | 16.77 | 0.3133 | 1.028 | 118 | 47.3 | — | — | — | — |
| 6 | 0.16202 | 4.115 | 26.25 | 13.30 | 0.3950 | 1.296 | 101 | 37.5 | 55 | 65 | 75 | 50 |
| 7 | 0.14429 | 3.665 | 20.82 | 10.55 | 0.4981 | 1.634 | 89 | 29.7 | — | — | — | — |
| 8 | 0.12849 | 3.264 | 16.51 | 8.366 | 0.6281 | 2.061 | 73 | 23.6 | 40 | 50 | 55 | 40 |
| 9 | 0.11442 | 2.906 | 13.09 | 6.634 | 0.7921 | 2.599 | 64 | 18.7 | — | — | — | — |
| 10 | 0.10190 | 2.588 | 10.38 | 5.261 | 0.9988 | 3.277 | 55 | 14.8 | 30 | 35 | 40 | 30 |
| 11 | 0.09074 | 2.305 | 8.234 | 4.172 | 1.259 | 4.132 | 47 | 11.8 | — | — | — | — |
| 12 | 0.08081 | 2.053 | 6.530 | 3.309 | 1.588 | 5.210 | 41 | 9.3 | 20 | 25 | 30 | 20 |
| 13 | 0.07196 | 1.828 | 5.178 | 2.624 | 2.003 | 6.570 | 35 | 7.4 | — | — | — | — |
| 14 | 0.06408 | 1.628 | 4.107 | 2.081 | 2.525 | 8.285 | 32 | 5.9 | 15 | 20 | 25 | — |
| 15 | 0.05707 | 1.450 | 3.257 | 1.650 | 3.184 | 10.45 | 28 | 4.7 | — | — | — | — |
| 16 | 0.05082 | 1.291 | 2.583 | 1.309 | 4.015 | 13.17 | 22 | 3.7 | — | — | — | — |
| 17 | 0.04526 | 1.150 | 2.048 | 1.038 | 5.063 | 16.61 | 19 | 2.9 | — | — | — | — |
| 18 | 0.04030 | 1.024 | 1.624 | 0.8230 | 6.385 | 20.95 | 16 | 2.3 | — | — | — | — |
| 19 | 0.03589 | 0.912 | 1.288 | 0.6527 | 8.051 | 26.41 | 14 | 1.8 | — | — | — | — |
| 20 | 0.03196 | 0.812 | 1.022 | 0.5176 | 10.15 | 33.31 | 11 | 1.5 | — | — | — | — |
| 21 | 0.02846 | 0.723 | 0.8101 | 0.4105 | 12.80 | 42.00 | 9 | 1.2 | — | — | — | — |
| 22 | 0.02535 | 0.644 | 0.6424 | 0.3255 | 16.14 | 52.96 | 7 | 0.9 | — | — | — | — |
| 23 | 0.02257 | 0.573 | 0.5095 | 0.2582 | 20.35 | 66.78 | 4.7 | 0.7 | — | — | — | — |
| 24 | 0.02010 | 0.511 | 0.4040 | 0.2047 | 25.67 | 84.21 | 3.5 | 0.6 | — | — | — | — |
| 25 | 0.01790 | 0.455 | 0.3204 | 0.1624 | 32.37 | 106.2 | 2.7 | 0.5 | — | — | — | — |
| 26 | 0.01594 | 0.405 | 0.2541 | 0.1288 | 40.81 | 133.9 | 2.2 | 0.4 | — | — | — | — |
| 27 | 0.01420 | 0.361 | 0.2015 | 0.1021 | 51.46 | 168.8 | 1.7 | 0.3 | — | — | — | — |
| 28 | 0.01264 | 0.321 | 0.1598 | 0.0810 | 64.89 | 212.9 | 0.83 | 0.2 | — | — | — | — |
| 29 | 0.01126 | 0.286 | 0.1267 | 0.0642 | 81.83 | 268.5 | 0.7 | 0.2 | — | — | — | — |
| 30 | 0.01003 | 0.255 | 0.1005 | 0.0509 | 103.2 | 338.5 | 0.52 | 0.1 | — | — | — | — |
| 31 | 0.00893 | 0.227 | 0.0797 | 0.0404 | 130.1 | 426.9 | 0.43 | 0.1 | — | — | — | — |
| 32 | 0.00795 | 0.202 | 0.0632 | 0.0320 | 164.1 | 538.3 | 0.3 | 0.1 | — | — | — | — |
| 33 | 0.00708 | 0.180 | 0.0501 | 0.0254 | 206.9 | 678.8 | 0.27 | 0.1 | — | — | — | — |
| 34 | 0.00630 | 0.160 | 0.0398 | 0.0201 | 260.9 | 855.9 | 0.21 | 0.1 | — | — | — | — |
| 35 | 0.00561 | 0.143 | 0.0315 | 0.0160 | 329.0 | 1079 | 0.17 | 0.0 | — | — | — | — |
| 36 | 0.00500 | 0.127 | 0.0250 | 0.0127 | 414.8 | 1361 | 0.13 | 0.0 | — | — | — | — |
| 37 | 0.00445 | 0.113 | 0.0198 | 0.0100 | 523.1 | 1716 | 0.1 | 0.0 | — | — | — | — |
| 38 | 0.00397 | 0.101 | 0.0157 | 0.0080 | 659.6 | 2164 | 0.08 | 0.0 | — | — | — | — |
| 39 | 0.00353 | 0.090 | 0.0125 | 0.0063 | 831.7 | 2729 | 0.065 | 0.0 | — | — | — | — |
| 40 | 0.00314 | 0.080 | 0.0099 | 0.0050 | 1049 | 3441 | — | 0.0 | — | — | — | — |
Click any row to populate the Quick Lookup panel. Resistance values are calculated for the selected conductor material.
NEC Temperature Correction Factors (75°C rated wire)
| Ambient Temperature | Correction Factor |
|---|---|
| ≤30°C (86°F) | 1.00 |
| 31–35°C (87–95°F) | 0.94 |
| 36–40°C (96–104°F) | 0.88 |
| 41–45°C (105–113°F) | 0.82 |
| 46–50°C (114–122°F) | 0.75 |
Per NEC 310.15(B)(2)(a). Multiply the listed ampacity by the correction factor for your ambient temperature.
Bundling Correction Factors
| No. of Conductors | Correction Factor |
|---|---|
| 1–3 | 1.00 |
| 4–6 | 0.80 |
| 7–24 | 0.70 |
| 25–42 | 0.65 |
| 43+ | 0.60 |
When multiple current-carrying conductors are bundled together, derate ampacity by this factor.
How to Use the AWG Wire Size Table
Look Up a Specific AWG Gauge
Type an AWG number in the AWG Lookup field — such as 12, 14, or 1/0 for zero-gauges. The detail panel on the right immediately shows diameter, cross-sectional area, resistance, NEC ampacity, skin depth frequency, and breaking force for that gauge. You can also click any row in the full reference table below to populate the lookup automatically.
Find AWG from a Diameter Measurement
Switch to the 'Diameter → AWG' tab and enter the wire's measured diameter in millimeters or inches. The tool calculates the exact AWG number using the inverse formula and shows the closest standard gauge with all its specifications.
Select Material and Filter the Table
Choose your conductor material (Copper, Aluminum, Silver, or five others) to update resistance values for that material. Use the Quick Presets to filter the table to relevant gauges for Home Wiring, Automotive, Audio/Speaker, Low Voltage, or Industrial applications. You can also toggle individual columns on and off to reduce visual clutter.
Export or Print the Reference Table
Click 'Export CSV' to download the currently filtered table with all data columns as a spreadsheet-compatible file. Click 'Print Table' to open the browser print dialog for a paper reference sheet. The visual size comparison chart at the top shows relative wire diameters for quick visual comparison.
Frequently Asked Questions
What AWG wire do I need for a 20-amp circuit?
For a standard 20-amp household circuit in the United States, you need AWG 12 copper wire. AWG 12 is rated at 20 amperes at 60°C and 25 amperes at 75°C per NEC Table 310.15(B)(16). This is the minimum size for 20-amp circuits feeding kitchen outlets, bathroom GFCI outlets, outdoor outlets, and small appliances. For very long runs (over 50–75 feet) where voltage drop may be a concern, some electricians upgrade to AWG 10 to keep the voltage drop below 3%, especially for motor loads.
What is the difference between chassis wiring ampacity and NEC ampacity?
Chassis wiring ampacity (also called equipment wiring ampacity) applies to short conductor runs inside equipment enclosures where open-air cooling is efficient and conductor length is minimal. These ratings are significantly higher than NEC ratings — for example, AWG 18 has a chassis wiring rating of 16 amps but no NEC rating. NEC Table 310.15(B)(16) ampacity applies to conductors in raceways, cables, or direct burial over potentially long runs where heat can accumulate. Always use NEC ratings for any building or permanent installation; use chassis ratings only for protected, short-run internal wiring inside listed equipment.
What does skin depth frequency mean for wire?
At high frequencies, alternating current does not flow uniformly through the entire cross-section of a conductor. Instead, it concentrates near the surface in a layer called the 'skin depth.' As frequency increases, the skin depth decreases, which means less of the conductor carries current — effectively increasing resistance. The skin depth frequency shown in this table is the frequency at which the skin depth equals the wire's radius. Above this frequency, the conductor behaves as though it is hollow, and its effective resistance at higher frequencies rises significantly above the DC value. This is important for RF coils, audio amplifier output stages, and high-frequency switching circuits.
Can I use aluminum wire instead of copper to save cost?
Aluminum wire is commonly used for large service entrance conductors (AWG 4 and larger), main feeder panels, and utility distribution lines because it is significantly lighter and cheaper than copper for large cross-sections. However, aluminum has approximately 61% of the conductivity of copper, so an aluminum conductor must be one or two sizes larger than copper to carry the same current. Additionally, aluminum forms an oxide layer that increases contact resistance at terminations, which requires special anti-oxidant compound and aluminum-rated connectors. In modern residential use, aluminum branch circuit wiring (AWG 12 and smaller) has largely been abandoned due to fire hazard concerns from improper connections; it remains acceptable and common for large-gauge feeders with proper terminations.
How does ambient temperature affect wire ampacity?
Wire insulation has a maximum continuous temperature rating — most residential wiring uses 60°C or 75°C-rated insulation. The NEC ampacity tables assume a maximum ambient temperature of 30°C (86°F). When the ambient temperature is higher — such as in an attic, near a furnace, or in outdoor conduit in a hot climate — the conductor cannot dissipate as much heat, so its ampacity must be derated. For 75°C-rated wire in 36–40°C ambient, multiply the listed ampacity by 0.88; in 41–45°C ambient, multiply by 0.82; and in 46–50°C ambient, multiply by 0.75. Always check the temperature correction table when routing conductors through high-temperature environments.
What is kcmil and how does it relate to AWG?
Kcmil stands for kilo circular mils, a unit of cross-sectional area used almost exclusively in North American electrical engineering for large conductors. One circular mil is the area of a circle with a diameter of 0.001 inch (one mil). A kcmil is 1,000 circular mils. The formula is Area(kcmil) = 1,000 × d(inches)². For AWG-sized conductors, kcmil is mainly used for AWG 0000 through AWG 1, after which conductors are typically specified directly in kcmil (e.g., 250 kcmil, 350 kcmil, 500 kcmil). The kcmil unit is related to AWG by the 700 circular mils per amp rule of thumb for power transmission wiring, where Amps = kcmil / 0.7.