Standard wire Gauge - wikipedia Standard wire Gauge A standard wire gauge. British Standard Wire Gauge is a set of wire sizes given by BS 3737 : 1964 ( now withdrawn ), and is generally abbreviated to SWG. It is also known as : Imperial Wire Gauge or British Standard Gauge. Use of SWG sizes has fallen greatly in popularity, but is still used as a measure of thickness in guitar strings and some electrical wire. Cross sectional area in square millimetres is now the more usual size measurement for wires used in electrical installation cables. The current British Standard for metallic materials such as wire and sheet is BS 6722 : 1986, which is a solely metric standard. SWG was fixed by Order of Council August 23, 1883. It was constructed by improving the Birmingham Wire Gauge. It was made a legal standard on March 1, 1884 by the British Board of Trade. SWG is not to be confused with American Wire Gauge which has a similar but not quite interchangeable numbering scheme. The basis of the system is the thou ( or mil in US English ), or 0.001 in. No. 7 / 0, the largest size, is 0.50 in. ( 500 thou or 12.7 mm ) in diameter, and the smallest, No. 50, is 0.001 in. ( 1 thou or about 25 μm ) in diameter. The wire diameter diminishes with increasing gauge size. Between each gauge, the weight per unit length diminishes by approximately 20 %. Because the weight per unit length is related to the area, and therefore the square of the diameter, the diameter diminishes by approximately 10.6 % : Diameter Ratio = 1 − 1 − 0.2 ≈ 10.6 % ( displaystyle ( mbox ( Diameter Ratio ) ) = 1 - ( sqrt ( 1 - 0.2 ) ) approx 10.6 % ) A table of wire gauges and diameters is shown below. The relationship of diameter to gauge is piecewise linear, only approximating a ( constant - ratio ) exponential curve. British Standard Wire Gauge ( SWG ) diameters SWG ( in ) ( mm ) Step 7 / 0 0.500 12.700 0.036 `` / gauge 6 / 0 0.464 11.786 0.032 `` / gauge 5 / 0 0.432 10.973 4 / 0 0.400 10.160 0.028 `` / gauge 3 / 0 0.372 9.449 0.024 `` / gauge 2 / 0 0.348 8.839 0 0.324 8.230 0.300 7.620 0.276 7.010 0.252 6.401 0.020 `` / gauge 0.232 5.893 0.212 5.385 6 0.192 4.877 0.016 `` / gauge 7 0.176 4.470 8 0.160 4.064 9 0.144 3.658 10 0.128 3.251 0.012 `` / gauge 11 0.116 2.946 12 0.104 2.642 13 0.092 2.337 14 0.080 2.032 0.008 `` / gauge 15 0.072 1.829 16 0.064 1.626 17 0.056 1.422 18 0.048 1.219 19 0.040 1.016 0.004 `` / gauge 20 0.036 0.914 21 0.032 0.813 22 0.028 0.711 23 0.024 0.610 0.002 `` / gauge 24 0.022 0.559 25 0.020 0.5080 26 0.018 0.4572 0.0016 `` / gauge 27 0.0164 0.4166 28 0.0148 0.3759 0.0012 `` / gauge 29 0.0136 0.3454 30 0.0124 0.3150 0.0008 `` / gauge 31 0.0116 0.2946 32 0.0108 0.2743 33 0.0100 0.2540 34 0.0092 0.2337 35 0.0084 0.2134 36 0.0076 0.1930 37 0.0068 0.1727 38 0.0060 0.1524 39 0.0052 0.1321 0.0004 `` / gauge 40 0.0048 0.1219 41 0.0044 0.1118 42 0.004 0.1016 43 0.0036 0.0914 44 0.0032 0.0813 45 0.0028 0.0711 46 0.0024 0.0610 47 0.0020 0.0508 48 0.0016 0.0406 49 0.0012 0.0305 0.0002 `` / gauge 50 0.0010 0.0254 See also Wire gauge comparison chart IEC 60228, the metric wire - size standard used in most parts of the world. Circular mil, Electrical industry standard for wires larger than 4 / 0. American Wire Gauge ( AWG ), used primarily in the US and Canada Stubs Iron Wire Gauge Jewelry wire gauge Body jewelry sizes Electrical wiring Number 8 wire, a term used in the New Zealand vernacular References Jump up ^ LewcoS Wire Tables 1962 Jump up ^ Russ Rowlett ( 2008 ), American and British Wire Gauges, University of North Carolina at Chapel Hill, retrieved 2011 - 04 - 06 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Standard_wire_gauge&oldid=853910810 '' Categories : Wire gauges Talk About Wikipedia Dansk Deutsch Français Edit links This page was last edited on 7 August 2018, at 19 : 23 ( UTC ). About Wikipedia

Question: difference between american wire gauge and standard wire gauge
Answer: similar but not quite interchangeable numbering scheme