SWG Wire Gauge Calculator: Find the Right Wire Size

⚡ SWG Wire Gauge Calculator

Convert Standard Wire Gauge sizes, find diameter, current capacity, resistance & cross-section

🔌 Quick Presets
🔧 Calculator Inputs
📊 Calculation Results
Always verify wire sizing with a qualified electrician. Never exceed the maximum rated current for any wire gauge. Apply appropriate derating for bundled or enclosed cables.
📋 SWG Wire Gauge Reference Chart
SWG Diameter (mm) Diameter (in) Area (mm²) Cu Current (A) Al Current (A) Resistance Ω/m (Cu)
17.6200.300045.601701300.000379
27.0100.276038.591501150.000448
45.8930.232027.27105800.000634
64.8770.192018.6875580.000926
84.0640.160012.9755420.001333
103.2510.12808.30235270.002084
122.6420.10405.48423180.003155
142.0320.08003.24315110.005334
161.6260.06402.075107.50.008343
181.2190.04801.16764.50.014832
200.9140.03600.65673.52.60.026349
220.7110.02800.39702.01.50.043580
240.5590.02200.24541.00.750.070483
260.4570.01800.16420.650.500.105360
280.3760.01480.11110.400.300.155640
300.3150.01240.077930.250.190.221920
320.2740.01080.058940.180.130.293200
360.1930.00760.029270.080.060.590700
400.1220.00480.011690.0250.0191.478000
500.0250.00100.0004910.00135.25000
🧮 Wire Material Properties
1.72
Copper Resistivity (μΩ·cm)
2.82
Aluminum Resistivity (μΩ·cm)
1.59
Silver Resistivity (μΩ·cm)
110
Nichrome Resistivity (μΩ·cm)
📐 Material Electrical Properties Comparison
Material Resistivity (μΩ·cm) Conductivity (%IACS) Density (g/cm³) Temp Coefficient (/°C) Melting Point (°C) Tensile Strength (MPa)
Copper (Annealed)1.7241008.960.003931083220
Copper (Hard Drawn)1.777978.960.003811083400
Aluminum (1350)2.826612.700.00403660160
Silver1.58710810.490.00380961170
Gold2.2147819.320.003401064130
Mild Steel17.20107.870.006501480500
Stainless Steel69.002.57.930.000941400700
Nichrome110.001.68.400.000171400700
📈 Current Capacity by Installation Type (Copper Wire)
SWG Diameter (mm) Open Air (A) In Conduit (A) Buried (A) In Wall (A) Typical Use
64.87775608045Sub-mains, large motors
84.06455445833Cooker, electric shower
103.25135283721Cooker circuits
122.64223182414Ring mains (large)
142.0321512169Ring mains, general power
161.626108116Lighting circuits
181.21964.86.53.6Low-power, controls
200.9143.52.83.82.1Signal, low-voltage
240.5591.00.81.10.6PCB traces, data
280.3760.40.320.430.24Instrumentation
📏 SWG to AWG Cross-Reference
SWG SWG Dia. (mm) Closest AWG AWG Dia. (mm) Difference (%) Common Application
84.06464.115+1.3%Heavy power feeds
103.25183.264+0.4%Cooker, A/C circuits
122.642102.588-2.1%Ring mains, dryers
142.032122.053+1.0%General purpose
161.626141.628+0.1%Lighting, low power
181.219171.150-5.7%Control circuits
200.914200.812-11.1%Signal, data
220.711220.644-9.4%Electronics
240.559230.574+2.7%PCB wiring
280.376270.361-4.0%Instrumentation
💡 Tip: Higher SWG Number = Thinner Wire. SWG (Standard Wire Gauge) works inversely — SWG 8 is much thicker than SWG 28. Always check the diameter in mm or inches to confirm the actual wire size when ordering.
⚠ Derating for Bundled Cables: When multiple cables are run together or enclosed in insulation, apply at least 15–20% derating to the current capacity. A single SWG 16 wire rated at 10A in open air should be derated to ~8A in conduit and ~6A in wall insulation.

Thought about wire gauge help to estimate as numbers in the world of wires says “how thick is this stuff?”. The number of the measure points the diameter, what matters because it directly shows how much current the wire can bear without overheating. One finds references to those measures in electrical and mechanical situations, although most folks meet them on the electrical side.

In United States the system AWG, that is the American wire gauge, is the usual for sizing wires. It exists almost since 1857 and received official approval in the specification ASTM B 258. The system operates for round, solid, non-iron electrical wires, that one mostly uses through North America.

What Wire Gauge Numbers Mean

What makes AWG interesting is that it is logarithmic, what sounds difficult, but really only shows that the sizes follow mathematical order instead of jump around randomly.

Here where folks commonly get confused. Opposite to your expectation, less big numbers point to thicker wires. Wire of 10th measure is much thicker compared to that of 20th measure.

The higher the number, the thinner the wire becomes. It is the reverse of that, what your mind probably wants to believe. The whole cause came from pulling of metal rod through plate with gradually more little holes; kind of cold pressure, where the metal gets narrow step after step to more final sizes.

Even so AWG is not the only option around. SWG, Standard wire Gauge, was the British method and it still appears in sum areas. Also exists the metric mode, that simply measures the cross-section area in square millimeters and leaves away the whole numerical trouble.

When it comes to really counting, what measure you have in hand, one uses physical tools for measuring. They usually are made up of round or oval discs with slices cut around the edge. Every slice bears stamped number, and you lay your wire in it, until it seats flatly.

Besides that one can take calipers and measure the diameter directly. Stainless steel gauge discs cost around six dollars.

For everyday home work the wire of 12th measure is the usual choice. Thinner types, like 16 to 18 AWG, work for short, low-power circuits, think about cables for speakers. And cost only pennies.

If you deal with longer ways or heavy power needs, even so, one wants 12 AWG or even thicker. The loss of voltage becomes a real problem hear. I observed, that 12th measure in 40 feet have only 0.2-volt loss, but if one goes down to 14th, it reaches 0.3 volt.

At 16th you find around 0.5 volt, and 18th push it to almost 0.8 volt. Typical USB-cables use 28 AWG for both energy and data. Telecom setups favour 24 or 22nd measure with solid wire.

Using thicker wire than required does not create troubles (it onlyexhausts your purse).

SWG Wire Gauge Calculator: Find the Right Wire Size

Author

  • Thomas Martinez

    Hi, I am Thomas Martinez, the owner of ToolCroze.com! As a passionate DIY enthusiast and a firm believer in the power of quality tools, I created this platform to share my knowledge and experiences with fellow craftsmen and handywomen alike.

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