Wire Gauge Chart (AWG)
In American Wire Gauge (AWG), a smaller number is a thicker wire. 14 AWG copper (1.63 mm) is used on 15-amp circuits, 12 AWG (2.05 mm) on 20-amp circuits and 10 AWG (2.59 mm) on 30-amp circuits.
AWG lookup
Source: ASTM B258: Standard specification for standard nominal diameters and cross-sectional areas of AWG sizes · All sources
Diameter to AWG
Look up any AWG size for its diameter, area, resistance and current rating, or measure a bare wire and find its gauge. The full chart covers 4/0 to 40 AWG.
AWG wire size chart
Diameters and areas are for solid round wire. Resistance is for annealed copper at 20 °C. Ampacity is from NEC Table 310.16 for not more than three current-carrying conductors in a cable or raceway at 30 °C ambient; "—" means the size isn't listed.
| AWG | Diameter (in) | Diameter (mm) | Area (mm²) | Area (cmil) | Copper Ω per 1,000 ft | Copper ampacity (A), NEC 310.16 | ||
|---|---|---|---|---|---|---|---|---|
| 60 °C | 75 °C | 90 °C | ||||||
| 4/0 | 0.4600 | 11.684 | 107.219 | 211,600 | 0.049 | 195 | 230 | 260 |
| 3/0 | 0.4096 | 10.405 | 85.029 | 167,806 | 0.0618 | 165 | 200 | 225 |
| 2/0 | 0.3648 | 9.266 | 67.431 | 133,077 | 0.0779 | 145 | 175 | 195 |
| 1/0 | 0.3249 | 8.251 | 53.475 | 105,535 | 0.0983 | 125 | 150 | 170 |
| 1 | 0.2893 | 7.348 | 42.408 | 83,693 | 0.1239 | 110 | 130 | 145 |
| 2 | 0.2576 | 6.544 | 33.631 | 66,371 | 0.1563 | 95 | 115 | 130 |
| 3 | 0.2294 | 5.827 | 26.67 | 52,635 | 0.197 | 85 | 100 | 115 |
| 4 | 0.2043 | 5.189 | 21.151 | 41,741 | 0.2485 | 70 | 85 | 95 |
| 5 | 0.1819 | 4.621 | 16.773 | 33,102 | 0.3133 | — | — | — |
| 6 | 0.1620 | 4.115 | 13.302 | 26,251 | 0.3951 | 55 | 65 | 75 |
| 7 | 0.1443 | 3.665 | 10.549 | 20,818 | 0.4982 | — | — | — |
| 8 | 0.1285 | 3.264 | 8.366 | 16,510 | 0.6282 | 40 | 50 | 55 |
| 9 | 0.1144 | 2.906 | 6.634 | 13,093 | 0.7921 | — | — | — |
| 10 | 0.1019 | 2.588 | 5.261 | 10,383 | 0.9988 | 30 | 35 | 40 |
| 11 | 0.0907 | 2.305 | 4.172 | 8,234 | 1.2595 | — | — | — |
| 12 | 0.0808 | 2.053 | 3.309 | 6,530 | 1.5882 | 20 | 25 | 30 |
| 13 | 0.0720 | 1.828 | 2.624 | 5,178 | 2.0027 | — | — | — |
| 14 | 0.0641 | 1.628 | 2.081 | 4,107 | 2.5254 | 15 | 20 | 25 |
| 15 | 0.0571 | 1.450 | 1.65 | 3,257 | 3.1844 | — | — | — |
| 16 | 0.0508 | 1.291 | 1.309 | 2,583 | 4.0155 | — | — | 18 |
| 17 | 0.0453 | 1.150 | 1.038 | 2,048 | 5.0634 | — | — | — |
| 18 | 0.0403 | 1.024 | 0.823 | 1,624 | 6.3849 | — | — | 14 |
| 19 | 0.0359 | 0.912 | 0.653 | 1,288 | 8.0512 | — | — | — |
| 20 | 0.0320 | 0.812 | 0.518 | 1,022 | 10.1524 | — | — | — |
| 21 | 0.0285 | 0.723 | 0.41 | 810 | 12.8019 | — | — | — |
| 22 | 0.0253 | 0.644 | 0.326 | 642 | 16.1429 | — | — | — |
| 23 | 0.0226 | 0.573 | 0.258 | 509 | 20.3558 | — | — | — |
| 24 | 0.0201 | 0.511 | 0.205 | 404 | 25.6682 | — | — | — |
| 25 | 0.0179 | 0.455 | 0.162 | 320 | 32.367 | — | — | — |
| 26 | 0.0159 | 0.405 | 0.129 | 254 | 40.8141 | — | — | — |
| 27 | 0.0142 | 0.361 | 0.102 | 202 | 51.4656 | — | — | — |
| 28 | 0.0126 | 0.321 | 0.081 | 160 | 64.8969 | — | — | — |
| 29 | 0.0113 | 0.286 | 0.064 | 127 | 81.8335 | — | — | — |
| 30 | 0.0100 | 0.255 | 0.051 | 101 | 103.1901 | — | — | — |
| 31 | 0.0089 | 0.227 | 0.04 | 80 | 130.1204 | — | — | — |
| 32 | 0.0080 | 0.202 | 0.032 | 63 | 164.0788 | — | — | — |
| 33 | 0.0071 | 0.180 | 0.025 | 50 | 206.8995 | — | — | — |
| 34 | 0.0063 | 0.160 | 0.02 | 40 | 260.8954 | — | — | — |
| 35 | 0.0056 | 0.143 | 0.016 | 32 | 328.9831 | — | — | — |
| 36 | 0.0050 | 0.127 | 0.013 | 25 | 414.84 | — | — | — |
| 37 | 0.0045 | 0.113 | 0.01 | 20 | 523.1036 | — | — | — |
| 38 | 0.0040 | 0.101 | 0.008 | 16 | 659.6214 | — | — | — |
| 39 | 0.0035 | 0.090 | 0.006 | 12 | 831.7673 | — | — | — |
| 40 | 0.0031 | 0.080 | 0.005 | 10 | 1,048.8392 | — | — | — |
Aluminum wire ampacity
Aluminum conducts about 61% as well as copper, so it needs a larger size for the same current. It's mainly used for service entrance cables and feeders in sizes 8 AWG and up.
| AWG | 60 °C | 75 °C | 90 °C |
|---|---|---|---|
| 12 | 15 | 20 | 25 |
| 10 | 25 | 30 | 35 |
| 8 | 35 | 40 | 45 |
| 6 | 40 | 50 | 55 |
| 4 | 55 | 65 | 75 |
| 3 | 65 | 75 | 85 |
| 2 | 75 | 90 | 100 |
| 1 | 85 | 100 | 115 |
| 1/0 | 100 | 120 | 135 |
| 2/0 | 115 | 135 | 150 |
| 3/0 | 130 | 155 | 175 |
| 4/0 | 150 | 180 | 205 |
Which ampacity column to use
The three columns match the temperature rating of the wire's insulation, but the lowest-rated part of the circuit sets the limit. Most residential breakers and device terminals are rated 60 °C or 75 °C, so for typical home wiring use the 60 °C column for 14–1 AWG (unless every termination is marked 75 °C) and the 75 °C column for larger sizes. The 90 °C column is for derating calculations when many wires share a raceway or the space is hot.
The AWG formula
AWG is a geometric series defined by two fixed points: 36 AWG is 0.005 in and 4/0 (numbered −3) is 0.46 in, with 39 steps between them.
d(n) = 0.005 in × 92(36 − n)/39 area in circular mils = (diameter in thousandths of an inch)²Example: 12 AWG is 0.005 × 9224/39 = 0.0808 in, or 2.053 mm. Its area is 80.8² ≈ 6,530 circular mils, about 3.31 mm². Copper resistance is 10.371 Ω·cmil/ft ÷ 6,530 cmil ≈ 1.59 Ω per 1,000 ft.
AWG is used in North America. The UK's old Standard Wire Gauge (SWG) and the gauges for sheet metal, screws and nails are different systems, so the same number means a different size in each.
Frequently asked questions
What size wire do I need for 20 amps?
12 AWG copper is the standard for 20-amp branch circuits in homes. The NEC limits 12 AWG copper to a 20-amp breaker (240.4(D)). Long runs may need 10 AWG to keep voltage drop down.
What size wire for 30 amps?
10 AWG copper, which the NEC limits to a 30-amp breaker. Typical 30-amp loads are electric dryers and some water heaters.
How many amps can 14 gauge wire carry?
14 AWG copper is rated 15 A at 60 °C, 20 A at 75 °C and 25 A at 90 °C in Table 310.16, but the NEC limits its overcurrent protection to 15 A. In practice, 14 AWG goes on 15-amp circuits.
What does 4/0 mean?
4/0 (said 'four aught') is the largest standard AWG size, 0.46 in across. The sizes above 1 AWG are 1/0, 2/0, 3/0 and 4/0, each larger than the last. Beyond 4/0, cable is sized in kcmil (thousands of circular mils).
Why does the gauge number go down as wire gets thicker?
AWG numbers come from the number of drawing steps in wire manufacture: thinner wire was pulled through more dies. Every 6 gauges halves the diameter, and every 3 gauges roughly halves the cross-sectional area.
Is stranded wire the same size as solid wire of the same gauge?
It has the same copper area, but its outside diameter is a little larger because of the gaps between strands. The diameters in this chart are for solid wire.
Sources
- ASTM B258: Standard specification for standard nominal diameters and cross-sectional areas of AWG sizes
- NFPA 70, National Electrical Code: Table 310.16 (ampacity) and 240.4(D) (small conductors)
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- November 5, 2026
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