AWG Cable Size Chart: How it Operates

FACTS CHECKED BY  Jose George​

When shopping around for electrical wire cables, you’ll notice plenty of sizes to select from. Wire cables are available in different thicknesses, i.e., gauge. Each thickness serves a different purpose.

For that reason, choosing a proper wire size is best when making a new installation. Or even when making extensions or rewiring. Wire conductor sizes should match the circuit’s amperage rating.

So that electrical circuits can go smoothly without overheating the insulation and, thus, fire. So, how do you determine the thickness of wire cables? The AWG cable size chart comes in handy.

Table of Contents

What is AWG( American Wire Gauge)?

The American Wire Gauge is a standardized wire gauge system in the US NEC (National Electrical Code) that determines the diameter of an electrical conductor. It determines copper and aluminum wire’s ampacity for electrical wiring installations.

J.R. Brown and Sharpe invented the AWG in 1856, which gives it another name, Brown & Sharpe Gauge. 

 In an AWG chart, the greater the integers, the smaller the wire sizes. The reverse also applies. The integer sizes include 16-, 14-, 12-, 10-, 8-, 6-, and 2- gauge wire. The wire size dictates the current safety passage through the wire. So, the lower the AWG size, the higher the ampacity, and vice versa. 

cable thickness 

cable thickness 

How to Measure the AWG with the Wire Gauge Tool?

When in the field and you want to estimate the wire gauge, you can use a high-quality device called the wire gauge tool. 

To measure the wire gauge, insert the wire in the slots one by one. Shift the wire around the gauge until it fits into the slots. Now, take the reading. 

Important: The wire gauge measuring tool lists the popular AWG sizes in a smaller circular disk.  

Calculating Wire Diameter in mm & Inch, Cross-Sectional Area in mm2, inch2 & kcmil & Resistance from AWG Size

Once you know the AWG size, you can calculate the wire diameter, cross-sectional area, and resistance based on the following math formula for each. Of course, you can use the wire size calculator for convenience.

Diameter calculations

We calculate a wire’s diameter in millimeters and inches. 

To calculate the diameter in millimeters, use the formula below:

Dn = 0.127 × 92(36-n)÷39

To calculate the diameter in inches, use the formula below:

dn (in) = 0.005 in × 92(36-n)/39

Key: 

D= The wire diameter 

n= Gauge size 

Wire cross-sectional area calculations

We calculate a wire’s cross-sectional area in Kcmil, square inches, and millimeters.

To calculate the cross-sectional area of the wire in kilo-circular mils (Kcmil), use the math formula below:

An (kcmil) = 1000×dn2 = 0.025 in2 × 92(36-n)/19.5.

To calculate the cross-sectional area in square inches (in2),  use the math formula below:

An (in2) = (π/4)×dn2 = 0.000019635 in2 × 92(36-n)/19.5

To calculate the cross-sectional area in square millimeters (mm2),  use the math formula below:

An (mm2) = (π/4)×dn2 = 0.012668 mm2 × 92(36-n)/19.5

Key: 

A= The cross-sectional area

n= Gauge size 

Wire resistance calculations

We measure resistance in two forms, Ohms per kilofeet (Ω/kft) or Ohms per Kilometer (Ω/km)

To calculate resistance in Ohms per kilofeet (Ω/kft), use the formula below:

Rn (Ω/kft) = 0.3048 × 109 × ρ(Ω·m) / (25.42 × An (in2))

To calculate resistance in Ohms per Kilometer (Ω/km), use the formula below:

Rn (Ω/km) = 109 × ρ(Ω·m) / An (mm2)

Key: 

R= The wire resistance 

n= Gauge size 

Why are AWG Charts Important?

The AWG charts are important in helping electrical experts and professionals determine the cable sizes, resistance, a conductor’s current carrying capacity, and many other parameters. In short, it’s a reference sheet.

  • Resistance

Measuring the amount of wire resistance in ohms was quite impossible. But, since 1857, AWG has had this impossibility fixed. The resistance in the AWG chart is for copper wire conductors. To calculate voltage drop, you can apply Ohm’s Law by using the given resistance. 

  • Ampacity

The key role of the AWG is to determine a conductor’s current rating. In other words, a conductor can safely carry the maximum current carrying capacity without overpowering its temperature rating

Maximum Frequency for 100% Skin Depth

Skin depth measures the farthest electrical conduction in a conductor. Usually, it’s a function of frequency. This concept is useful in high-frequency AC engineering. When calculating a wire’s resistance, always consider the skin depth effect. According to the AWG chart, the calculated skin depth must equal the radius of the wire.

Breaking Force for Copper Wire

Copper has the highest breaking strength compared to other wire materials, such as aluminum. With that said, you need more force to break it. The amount of force will be dependent on the size and shape of the wire. 

Thinner wires are weaker than thicker wires, while longer wires have higher breaking strength than shorter wires. To establish the force f needed to break a piece of copper wire, you’ll need to measure the diameter and length first. The AWG chart and wire gauge tool come in assistance. 

Copper wires in different sizes 

Copper wires in different sizes 

AWG Gauge Chart & Table

Below is the wire gauge chart (including the wire ampacity chart) showing various data estimations, including wire diameter, cross-sectional wire area, resistance, frequency, and current rating. 

AWGDiameter (in)Diameter (mm)Wire Cross-sectional area (kcmil)Wire Cross-sectional Area (mm)Ohms/1000ftOhms/kmMax Amp for chassis wiring Max Amps for power transmissionMax frequency(Skin depth)Breaking force 
0000
(4/0)
0.4611.6842121070.0490.16072380302125 Hz6120 lbs
000
(3/0)
0.409610.4038416884.90.06180.202704328239160 Hz4860 lbs
00
(2/0)
0.36489.2659213367.40.07790.255512283190200 Hz3860 lbs
0
(1/0)
0.32498.2524610653.50.09830.322424245150250 Hz3060 lbs
10.28937.3482283.742.40.12390.406392211119325 Hz2430 lbs
20.25766.5430466.433.60.15630.51266418194410 Hz1930 lbs
30.22945.8267652.626.70.1970.6461615875500 Hz1530 lbs
40.20435.1892241.721.10.24850.8150813560650 Hz1210 lbs
50.18194.6202633.116.80.31331.02762411847810 Hz960 lbs
60.1624.114826.313.30.39511.295928101371100 Hz760 lbs
70.14433.6652220.810.60.49821.63409689301300 Hz605 lbs
80.12853.263916.58.370.62822.06049673241650 Hz480 lbs
90.11442.9057613.16.630.79212.59808864192050 Hz380 lbs
100.10192.5882610.45.260.99893.27639255152600 Hz314 lbs
110.09072.303788.234.171.264.132847123200 Hz249 lbs
120.08082.052326.533.311.5885.20864419.34150 Hz197 lbs
130.0721.82885.182.632.0036.56984357.45300 Hz150 lbs
140.06411.628144.112.082.5258.282325.96700 Hz119 lbs
150.05711.450343.261.653.18410.44352284.78250 Hz94 lbs
160.05081.290322.581.314.01613.17248223.711 kHz75 lbs
170.04531.150622.051.045.06416.60992192.913 kHz59 lbs
180.04031.023621.620.8236.38520.9428162.317 kHz47 lbs
190.03590.911861.290.6538.05126.40728141.821 kHz37 lbs
200.0320.81281.020.51910.1533.292111.527 kHz29 lbs
210.02850.72390.8100.41212.841.98491.233 kHz23 lbs
220.02530.645160.6420.32716.1452.939270.9242 kHz18 lbs
230.02260.574040.5090.25920.3666.78084.70.72953 kHz14.5 lbs
240.02010.510540.4040.20525.6784.19763.50.57768 kHz11.5 lbs
250.01790.454660.3200.16232.37106.17362.70.45785 kHz9 lbs
260.01590.403860.2540.12840.81133.85682.20.361107 kHz7.2 lbs
270.01420.360680.2020.10251.47168.82161.70.288130 kHz5.5 lbs
280.01260.320040.1600.08064.9212.8721.40.226170 kHz4.5 lbs
290.01130.287020.1270.064781.83268.40241.20.182210 kHz3.6 lbs
300.010.2540.1010.0507103.2338.4960.860.142270 kHz2.75 lbs
310.00890.226060.07970.0401130.1426.7280.70.113340 kHz2.25 lbs
320.0080.20320.06320.0324164.1538.2480.530.091430 kHz1.8 lbs
330.00710.180340.05010.0255206.9678.6320.430.072540 kHz1.3 lbs
340.00630.160020.03980.0201260.9855.7520.330.056690 kHz1.1 lbs
350.00560.142240.03150.01593291079.120.270.044870 kHz0.92 lbs
360.0050.1270.02500.0127414.813600.210.0351100 kHz0.72 lbs
370.00450.11430.01980.0103523.117150.170.02891350 kHz0.57 lbs
380.0040.10160.01570.00811659.621630.130.02281750 kHz0.45 lbs
390.00350.08890.01250.00621831.827280.110.01752250 kHz0.36 lbs
400.00310.078740.09890.00487104934400.090.01372900 kHz0.29 lbs

Conclusion

Selecting a wire with the right thickness is essential in every electrical installation. Whether home-based or industrial-based. All you need is an AWG cable size chart, and your work is made easier. 

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