12 AWG Wire Specs
Ampacity, geometry, resistance, conduit fill and maximum run length for 12 AWG conductors in copper and aluminium.
Quick answer
12 AWG copper carries about 24 A at 75 °C (20 A at 60 °C, 27 A at 90 °C). The bare conductor is 0.0808 in (2.05 mm) and 6,530 circular mils, with 1.5882 Ω per 1000 ft. It pairs with a 20 A breaker at 75 °C terminations.
Copper 75 °C
24A
Aluminium 75 °C
19A
Diameter
0.0808in
Circular mils
6,530
Full specification
| Size designation | 12 AWG |
|---|---|
| AWG gauge number | 12 |
| Circular mils | 6,530 |
| kcmil | 6.53 |
| Bare diameter (in) | 0.0808 |
| Bare diameter (mm) | 2.052 |
| Cross-section (mm²) | 3.31 |
| THHN/THWN-2 OD (in) | 0.130 |
| Insulated area (sq in) | 0.0133 |
| Copper resistance (Ω/1000 ft) | 1.5882 |
| Aluminium resistance (Ω/1000 ft) | 2.6034 |
| Max standard breaker (Cu, 75 °C) | 20 A |
Published standard — source: Geometry computed from the ASTM B258 AWG formula; resistance from standard resistivityFormula estimate — source: Ampacity from the site model
Ampacity with derating
Estimated ampacity from the 90 °C column at various ambient temperatures and conductor counts.
| Conductors in raceway | 30 °C ambient | 40 °C ambient | 50 °C ambient | 60 °C ambient |
|---|---|---|---|---|
| 3 | 27 A | 25 A | 22 A | 19 A |
| 6 | 22 A | 20 A | 18 A | 15 A |
| 9 | 19 A | 17 A | 15 A | 13 A |
| 15 | 14 A | 12 A | 11 A | 10 A |
| 25 | 12 A | 11 A | 10 A | 9 A |
Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 24 A. Run your own conditions.
Maximum run length at 3% voltage drop
One-way distance for 12 AWG copper before drop exceeds 3%.
| Load | 120 V 1Ø | 240 V 1Ø | 208 V 3Ø | 480 V 3Ø |
|---|---|---|---|---|
| 10 A | 91 ft | 182 ft | 182 ft | 420 ft |
| 15 A | 60 ft | 121 ft | 121 ft | 280 ft |
| 20 A | 45 ft | 91 ft | 91 ft | 210 ft |
| 30 A | 30 ft | 60 ft | 60 ft | 140 ft |
| 40 A | 22 ft | 45 ft | 45 ft | 105 ft |
| 50 A | 18 ft | 36 ft | 36 ft | 84 ft |
How many 12 AWG conductors fit in conduit
Maximum count of this size alone, at the fill percentage matching the resulting count.
| Conduit | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| EMT | 9 | 16 | 26 | 45 | 61 | 101 | 176 | 266 | 347 | 400 |
| IMC | 10 | 17 | 28 | 49 | 67 | 109 | 154 | 238 | 318 | 400 |
| RMC | 9 | 16 | 26 | 45 | 62 | 102 | 146 | 225 | 301 | 388 |
| PVC Sch 40 | 8 | 15 | 25 | 43 | 59 | 99 | 141 | 219 | 293 | 378 |
| PVC Sch 80 | 6 | 12 | 20 | 37 | 51 | 86 | 124 | 194 | 261 | 339 |
Neighbouring sizes
Frequently asked
- How many amps can 12 AWG wire carry?
- 12 AWG copper is estimated at 20 A at 60 °C, 24 A at 75 °C and 27 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 19 A at 75 °C.
- What breaker size goes with 12 AWG copper?
- The largest standard overcurrent device that 12 AWG copper supports at 75 °C is 20 A. For a continuous load, the load itself must not exceed 80% of that rating.
- What is the diameter of 12 AWG wire?
- The bare conductor is 0.0808 inches (2.052 mm) in diameter, which is 6,530 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.130 inches.
- What is the resistance of 12 AWG wire?
- About 1.5882 ohms per 1000 feet for copper and 2.6034 ohms per 1000 feet for aluminium, at 75 °C.
- How far can I run 12 AWG wire?
- Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 12 AWG copper stays under 3% voltage drop for about 45 feet one-way. Doubling the voltage roughly doubles the allowable distance.
Materials for this size
Materials for this size
Wire, cable and terminations for 12 AWG.
- THHN/THWN-2 12 AWG copper12 AWG copperBuilding wire in the size this page covers (12 AWG copper).Check price on Amazon →
- NM-B cable 12 AWG12 AWGRomex-type cable for dry indoor branch circuits at this size.Check price on Amazon →
- Wire connectors for 12 AWG12 AWGPush-in or twist-on connectors rated for this conductor size.Check price on Amazon →
- Terminal lugs & anti-oxidantCopper-rated mechanical lugs for panel and disconnect terminations.Check price on Amazon →
Links go to Amazon search results, not a single listing — confirm ratings, insulation type and listing details before buying, and make sure the part is approved for your application.
Related charts & calculators
- Voltage Drop CalculatorPercent drop, end voltage and minimum conductor for any run length.
- Conduit Fill CalculatorFill percentage and maximum conductor count for EMT, RMC, IMC and PVC.
- Breaker Size CalculatorOvercurrent device rating and minimum conductor from load current.
- Wire Ampacity CalculatorDerated ampacity for ambient temperature and bundled conductors.
- Box Fill CalculatorVolume allowances for conductors, clamps, devices and grounds per NEC 314.16.
- Ampacity ChartEstimated allowable ampacity by conductor size, material and insulation rating.