American Wire Gauge “AWG” Chart – Wire Size & Ampacity Table

AWG – American Wire Gauge Chart – Wire Size & Amps Rating Table

American Wire Gauge “AWG” is one of the important and standard tools in the US NEC (National Electrical Codes) used to sizing different cables and wires for multiple applications. Similarly to the SWG (Standard Wire Gauge) used in the UK, AWG is used to determine the ampacity of copper and aluminum wires for electrical wiring installations etc.

The AWG tables and charts are handy methods to specify the current carrying capacity of a conductor, its diameter, resistance, max current in amperes and other important parameters and characteristics.

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AWG – American Wire Gauge

It is impossible to measure the exact amount of resistance in ohms of a wire having specific length for precise wire diameter. That’s where the AWG (American Wire Gauge) has played an important role since 1857.

The AWG is used to exactly measure the diameter of a particular conductor (such as solid, stranded, round and non-ferrous (alloys or metals that do not contain any appreciable amounts of iron) materials e.g. Aluminum, Copper etc). One of the most important roles of American Wire Gauge is to measure the current carrying capacity in Amps of wire (aka Wire Ampacity = The amount of maximum current that a conductor can carry continuously without exceeding its temperature rating.

One thing should be noted about the AWG that the larger the integer, the smaller the thickness and diameter of wire. For example, the 14AWG size is a suitable wire for a 15Amp circuit breaker, whereas the 8AWG size is most appropriate for 40Amps of circuit breakers and load points. In short, the ampacity is inversely proportional to the size of AWG integers (from 0000AWG to 40AWG) e.g. the higher the AWG size, the lower the ampacity and vise versa.

Good to know: The American Wire Gauge (AWG) is also known as B and S Gauge (Brown & Sharpe Gauge).

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The Wire Gauge (Measuring Tool)

If you are on the job site and need to know the wire size gauge for the particular load, one of the quick solutions is to use the handy device known as wire gauge tool. It is a small circular shaped disc where different but common numbers are printed on it in accordance with the specific slots and holes.

To use the wire gauge tool to find the suitable gauge size for a particular wire, simply remove the outer insulation and insert the wire conductor in the wire gauge slot one by one. If it is fixed properly in the slot (not hole), this is the exact gauge size (printed on that specific slot) of the wire.

Why are Wire Gauge Charts & Tables Important?

In any electrical installation system whether domestic or industrial, the selection of proper wire size and appropriate size of circuit breaker is very important. For example, if you need to install a water heater, what size of wire will you select? As you can’t use the same size of wire for all the electrical load points and higher wattage appliances. If so, the small wire for higher load may get hotter which leads to burn the wire as well as damage the circuit breaker and connected appliance to it. That’s where we need an AWG tool and related charts and tables to it.

Based on the wire size chart, you may select an “8 AWG” wire size and 50A of circuit breaker for 240V, 9000W, 240V water heater element wattage. We will show a solved example as well as the related AWG Wire size table for this in the following sections.

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Wire Gauge Chart & Table – AWG Gauge

The integers (as numbers) printed on the American Wire Gauge shows the gauge size. In AWG, there are a total of 44 gauges assigned to different numbers. In the list of standard sizes as integers, 4/0 (0000) is the largest diameter and 40AWG is the smallest diameter printed on AWG.

In addition, there are some special gauges such as 0000 (4/0), 000 (3/0), 00 (2/0) used for wire diameter and thickness larger than 0AWG. Instead of these complex stuff, wire gauge tables and charts are the alternative helpful resources based on the AWG. In these AWG gauge charts, most common gauge values show the different characteristics of wire such as its diameter, area, ampacity, resistance, current density, fusing current and temperature ratings etc.

The following AWG “American Wire Gauge” table shows the AWG Size and diameter in millimeter “mm” and inches in “in”, its cross sectional area in mm2, Inche2 and kcmil or MCM and resistance in ohms per 1000 feet and 1000 meter. The AWG size chart also shows the current in amperes for chassis wiring and power transfer application.

 AWG # Diameter Cross Section Area Resistance in Ω Current in Amps mm inch mm2 Inch2 kcmil Ω / kft Ω / km Chassis Wiring Power Transfer 0000 (4/0) 11.6840 0.4600 107.2193 0.1662 211.6000 0.049 0.1608 380 302 000 (3/0) 10.4049 0.4096 85.0288 0.1318 167.8064 0.0618 0.2028 328 239 00 (2/0) 9.2658 0.3648 67.4309 0.1045 133.0765 0.0779 0.2557 283 190 0 (1/0) 8.2515 0.3249 53.4751 0.0829 105.5345 0.0983 0.3224 245 150 1 7.3481 0.2893 42.4077 0.0657 83.6927 0.1239 0.4066 211 119 2 6.5437 0.2576 33.6308 0.0521 66.3713 0.1563 0.5127 181 94 3 5.8273 0.2294 26.6705 0.0413 52.6348 0.197 0.6464 158 75 4 5.1894 0.2043 21.1506 0.0328 41.7413 0.2485 0.8152 135 60 5 4.6213 0.1819 16.7732 0.0260 33.1024 0.3133 1.028 118 47 6 4.1154 0.1620 13.3018 0.0206 26.2514 0.3951 1.296 101 37 7 3.6649 0.1443 10.5488 0.0164 20.8183 0.4982 1.634 89 30 8 3.2636 0.1285 8.3656 0.0130 16.5097 0.6282 2.061 73 24 9 2.9064 0.1144 6.6342 0.0103 13.0927 0.7921 2.599 64 19 10 2.5882 0.1019 5.2612 0.0082 10.3830 0.9988 3.277 55 15 11 2.3048 0.0907 4.1723 0.0065 8.2341 1.26 4.132 47 12 12 2.0525 0.0808 3.3088 0.0051 6.5299 1.588 5.211 41 9.3 13 1.8278 0.0720 2.6240 0.0041 5.1785 2.003 6.571 35 7.4 14 1.6277 0.0641 2.0809 0.0032 4.1067 2.525 8.285 32 5.9 15 1.4495 0.0571 1.6502 0.0026 3.2568 3.184 10.448 28 4.7 16 1.2908 0.0508 1.3087 0.0020 2.5827 4.015 13.174 22 3.7 17 1.1495 0.0453 1.0378 0.0016 2.0482 5.063 16.612 19 2.9 18 1.0237 0.0403 0.8230 0.0013 1.6243 6.385 20.948 16 2.3 19 0.9116 0.0359 0.6527 0.0010 1.2881 8.051 26.415 14 1.8 20 0.8118 0.0320 0.5176 0.0008 1.0215 10.152 33.308 11 1.5 21 0.7229 0.0285 0.4105 0.0006 0.8101 12.802 42.001 9 1.2 22 0.6438 0.0253 0.3255 0.0005 0.6424 16.143 52.962 7 0.92 23 0.5733 0.0226 0.2582 0.0004 0.5095 20.356 66.784 4.7 0.729 24 0.5106 0.0201 0.2047 0.0003 0.4040 25.668 84.213 3.5 0.577 25 0.4547 0.0179 0.1624 0.0003 0.3204 32.367 106.19 2.7 0.457 26 0.4049 0.0159 0.1288 0.00025 0.2541 40.814 133.9 2.2 0.361 27 0.3606 0.0142 0.1021 0.00020 0.2015 51.466 168.85 1.7 0.288 28 0.3211 0.0126 0.0810 0.00013 0.1598 64.897 212.92 1.4 0.226 29 0.2859 0.0113 0.0642 0.00010 0.1267 81.833 268.48 1.2 0.182 30 0.2546 0.0100 0.0509 0.00008 0.1005 103.19 338.55 0.86 0.142 31 0.2268 0.0089 0.0404 0.00006 0.0797 130.12 426.9 0.7 0.113 32 0.2019 0.0080 0.0320 0.00005 0.0632 164.08 538.32 0.53 0.091 33 0.1798 0.0071 0.0254 0.00004 0.0501 206.9 678.8 0.51 0.088 34 0.1601 0.0063 0.0201 0.000031 0.0398 260.9 855.96 0.43 0.072 35 0.1426 0.0056 0.0160 0.000025 0.0315 328.98 1,079.3 0.43 0.072 36 0.1270 0.0050 0.0127 0.000020 0.0250 414.84 1,361 0.33 0.056 37 0.1131 0.0045 0.0100 0.000016 0.0198 523.1 1,716.2 0.33 0.056 38 0.1007 0.0040 0.0080 0.000012 0.0157 659.62 2,164.1 0.27 0.044 39 0.0897 0.0035 0.0063 0.000010 0.0125 831.77 2,728.9 0.26 0.043 40 0.0799 0.0031 0.0050 0.000008 0.0099 1,048.8 3,441.1 0.21 0.035

Note: Resistance of wires in Ω/km and Ω/kft are at 20°C or 68°F.

Here is the AWG wire size chart in image format if you need to download it for reference.

Click image to enlarge

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Calculation of Wire Diameter in mm & Inch, Cross Sectional Area in mm2, inch2 & kcmil & Resistance from it AWG Size

Wire Diameter in millimeters “mm“.

Dn = 27 × 10-3 × 92(36-n)÷39

or

DAWG = 8.251 × e-(0.1159) (AWG)     …     In millimeters (mm).

Where:

• D = The wire diameter in millimeter “mm”.
• n & AWG = Number of the gauge size.

Note: For larger gauge sizes like 4/0 (0000), 3/0 (000), 2/0 (00) & 0 (1/0), you may use the numbers for AWG as -3, -2, -1 and 0 respectively.

Wire Diameter in Inches “in”.

Dn = 5 × 10-3 × 92(36-n)÷39    …     In inches

Where:

• D = The wire diameter in inches “in”.
• n = Number of the gauge size.

Wire Cross Sectional Area in Square Millimeter “mm2“.

An = (π ÷ 4) × Dn2

An = 12.668 × 10-392(36-n)÷19.5

Where:

• An = Cross sectional area of “n” gauge wire size in square millimeters “mm2“.
• n = The number “#” of gauge size.
• D = Wire square diameter in “mm2“.

Wire Cross Sectional Area in Square Inches “in2“.

An (π ÷ 4) × Dn2

A= 19635 × 10-6 × 92(36-n)÷19.5

Where:

• An = Cross sectional area of “n” gauge wire size in square inches “in2“.
• n = The number “#” of gauge size.
• D = Wire square diameter in “in2“.

Wire Cross Sectional Area in kcmil “kilo circular mils”.

An = 1000 × Dn2 = 0.025 × 92(36-n)÷19.5

Where:

• An = cross sectional area of “n” gauge wire size in kcmil.
• kcmil = kilo circular mils.
• n = the number of gauge size.
• D = wire square diameter in in2.

Note: kcmil is also known as MCM “thousands of circular mils” i.e. 1kcmil = 1MCM = 0.5067 mm2.

• 2 MCM ≈ 1 mm2
• 1000 mils = 1 inch

In addition, MCM and kcmil is used for large diameter wires in AWG.

Resistance per 1000 feet at 20°C or 68°F:

R= 0.3048 × 109 × ρ ÷ (25.42An)

Where;

• R = Resistance of the wire conductors in “Ω/kft”.
• n = # of gauge size.
• ρ = rho = resistivity in (Ω·m).
• An = the cross sectional area of n #gauge in square inches “in2“.

Resistance per 1000 Meters at 20°C or 68°F:

R= 109 × ρ ÷ An

Where

• R = Resistance of the wire conductors “in Ω/km”.
• n = # of gauge size.
• ρ = rho = resistivity in (Ω·m).
• An = the cross sectional area of n #gauge in square millimeters “mm2“.

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Wire Size Ampacity & Breaker Size Charts Based on AWG

Derived from the wire gauge chart and based on AWG sizes, the following fig shows the commonly used wire gauge size for different applications.

Click image to enlarge

The following AWG table shows the different AWG gauges and its associated ampacities and wire applications.

 Wire Gauge Rated Ampacity Wire Applications 4/0 (0000) 260 Amps The largest wire size likely to be found at residential electrical installations 3/0 (000) 200 Amps Service entrance and feeder cable 1/0 (0) 150 Amps Service entrance and feeder cable 2 Gauge 95 Amps Large water heater elements 4 Gauge 70 Amps Electric furnaces, large electric heaters 6 Gauge 55 Amps Furnaces, cooktops and electric ranges 10 Gauge 30 Amps Electric clothes dryers, 240V window Air Conditioners, electric water heaters 12 Gauge 20 Amps Kitchen, bathroom & outdoor receptacles (outlets) – 120V Air Conditioners 14 Gauge 15 Amps Light fixtures, lamps, receptacles, lighting circuits 16-Gauge 13 Amps Extension cords (light-duty) 18 Gauge 10 Amps Low-voltage lighting and lamp cords

You may downlead the above table as a reference sheet as follow:

Click image to enlarge

The following two charts shows the suitable circuit breaker sizes in Amps with wire gauge sizes and different level of voltages.

Click image to enlarge

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NEC Wire Size Table 310.15(B)(16) (Previously Table 310.16) & Chart based on AWG

NEC (National Electrical Code) Table 310.15(B)(16) (formerly Table 310.16) – 310.60 – ARTICLE 310 – Conductors for General Wiring & Allowable Ampacities of Conductors & Wire Sizes based on AWG (American Wire Gauge).

 310.60               ARTICLE 310 — CONDUCTORS FOR GENERAL WIRING Table 310.15(B)(16) (formerly Table 310.16) Allowable Ampacities of Insulated Conductors Rated Up to and Including 2000 Volts, 60°C Through 90°C (140°F Through 194°F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F)* Size AWG or kcmil Temperature Rating of Conductor [See Table 310.104(A).] Size AWG or kcmil 60°C (140°F) 75°C (167°F) 90°C (194°F) 60°C (140°F) 75°C (167°F) 90°C (194°F) Types TW, UF Types RHW, THHW, THW, THWN, XHHW, USE, ZW Types TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, ZW-2 Types TW, UF Types RHW, THHW, THW, THWN, XHHW, USE Types TBS, SA, SIS, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHH, XHHW, XHHW-2, ZW-2 COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 18** — — 14 — — — — 16** — — 18 — — — — 14** 15 20 25 — — — — 12** 20 25 30 15 20 25 12** 10** 30 35 40 25 30 35 10** 8 40 50 55 35 40 45 8 6 55 65 75 40 50 55 6 4 70 85 95 55 65 75 4 3 85 100 115 65 75 85 3 2 95 115 130 75 90 100 2 1 110 130 145 85 100 115 1 1/0 125 150 170 100 120 135 1/0 2/0 145 175 195 115 135 150 2/0 3/0 165 200 225 130 155 175 3/0 4/0 195 230 260 150 180 205 4/0 250 215 255 290 170 205 230 250 300 240 285 320 195 230 260 300 350 260 310 350 210 250 280 350 400 280 335 380 225 270 305 400 500 320 380 430 260 310 350 500 600 350 420 475 285 340 385 600 700 385 460 520 315 375 425 700 750 400 475 535 320 385 435 750 800 410 490 555 330 395 445 800 900 435 520 585 355 425 480 900 1000 455 545 615 375 445 500 1000 1250 495 590 665 405 485 545 1250 1500 525 625 705 435 520 585 1500 1750 545 650 735 455 545 615 1750 2000 555 665 750 470 560 630 2000 *Refer to 310.15(B)(2) for the ampacity correction factors where the ambient temperature is other than 30°C (86°F). Refer to 310.15(B)(3)(a) for more than three current-carrying conductors.    **Refer to 240.4(D) for conductor overcurrent protection limitations.

Here is the NEC table as a chart (image format to downloads as a reference)

Click image to enlarge