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 nonferrous (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 mm^{2}, Inche^{2} 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  mm^{2}  Inch^{2}  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 mm^{2}, inch^{2} & kcmil & Resistance from it AWG Size
Wire Diameter in millimeters “mm“.
D_{n} = 27 × 10^{3} × 92^{(36n)÷39}
or
D_{AWG} = 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”.
D_{n} = 5 × 10^{3} × 92^{(36n)÷39} … In inches
Where:
 D = The wire diameter in inches “in”.
 n = Number of the gauge size.
Wire Cross Sectional Area in Square Millimeter “mm^{2}“.
A_{n} = (π ÷ 4) × D_{n}^{2}
A_{n} = 12.668 × 10^{3} V 92^{(36n)÷19.5}
Where:
 A_{n} = Cross sectional area of “n” gauge wire size in square millimeters “mm^{2}“.
 n = The number “#” of gauge size.
 D = Wire square diameter in “mm^{2}“.
Wire Cross Sectional Area in Square Inches “in^{2}“.
A_{n} = (π ÷ 4) × D_{n}^{2}
A_{n }= 19635 × 10^{6} × 92^{(}^{36n)÷19.5}
Where:
 An = Cross sectional area of “n” gauge wire size in square inches “in^{2}“.
 n = The number “#” of gauge size.
 D = Wire square diameter in “in^{2}“.
Wire Cross Sectional Area in kcmil “kilo circular mils”.
A_{n} = 1000 × D_{n}^{2} = 0.025 × 92^{(36n)÷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 in^{2}.
Note: kcmil is also known as MCM “thousands of circular mils” i.e. 1kcmil = 1MCM = 0.5067 mm^{2}.
 2 MCM ≈ 1 mm^{2}
 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_{n }= 0.3048 × 10^{9} × ρ ÷ (25.4^{2}x A_{n})
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 “in^{2}“.
Resistance per 1000 Meters at 20°C or 68°F:
R_{n }= 10^{9} × ρ ÷ A_{n}
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 “mm^{2}“.
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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 
16Gauge  13 Amps  Extension cords (lightduty) 
18 Gauge  10 Amps  Lowvoltage 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 CurrentCarrying 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, RHW2, THHN, THHW,
THW2, THWN2, USE2, XHH, XHHW, XHHW2, ZW2 
Types TW, UF  Types RHW, THHW, THW, THWN, XHHW, USE  Types TBS, SA, SIS, THHN, THHW,
THW2, THWN2, RHH, RHW2, USE2, XHH, XHHW, XHHW2, ZW2 

COPPER  ALUMINUM OR COPPERCLAD 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 

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