Standard Wire Gauge (SWG) Calculator – Size Chart & Cable Properties

SWG “Standard Wire Gauge” Size Calculator & Cable Properties Table & Chart

Standard Wire Gauge “SWG” Calculator

The following Standard Wire Gauge (SWG) calculator will calculate the diameter in inches, mm, cross sectional area in inches², mm², and kcmil or MCM, resistance per 1000 feet and per 1000 meters and the maximum current capacity in amperes. To calculate the values, just select or enter the SWG size and hit the “Calculate” button to get the result of different properties of SWG cables and wires.

• Related Calculator : American Wire Gauge “AWG” Calculator – AWG Size Chart & Table

Good to know: SWG or Standard Wire Gauge used for wire sizing and properties is also known as “British Standard Wire Gauge” and “British Standard Gauge” or “Imperial Wire Gauge”.

*The data for resistance of copper and other wires in Ω/km and Ω/kft are at 20°C or 68°F.

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Wire Diameter in mm & Inch, Area in inch², mm² & kcmil and Resistance in Ω/kft & Ω/km Calculations

Wire Diameter in Inches “in”.

d_n = 5 x 10^-3 x 92^(36-n)÷39 = 0.005 x 92^(36-n)÷39

Wire Diameter in mm “millimeters”.

d_n = 27 x 10^-3 x 92^(36-n)÷39 = 0.127 x 92^(36-n)÷39

Wire Cross Sectional Area in Square Inches “in²“.

A_n = (π ÷ 4) x d_n²= 19635 x 10^-6 x 92^(36-n)÷19.5

Wire Cross Sectional Area in Square Millimeter “mm²“.

A_n = (π ÷ 4) x d_n² = 12.668 x 10^-3 x 92^(36-n)÷19.5

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

A_n = 1000 x d_n² = 0.025 x 92^(36-n)÷19.5

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

R_n = 0.3048 x 10⁹ × ρ ÷ (25.4²x A_n)

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

R_n = 10⁹ x ρ ÷ A_n

Where: 

• n = Number of the gauge size. 
• d = The wire diameter in inches, mm, inches², & mm² respectively.
• A_n = Cross sectional area of “n” gauge wire size in inches², “mm²” & kcmil respectively.
• R = Resistance of the wire conductors in Ω/kft & Ω/km respectively.
• ρ = rho = resistivity in (Ω·m).

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Standard Wire Gauge “SWG” Size Chart & Table

The following SWG “Standard Wire Gauge” table shows the SWG size and diameter in inches “in” and millimeter “mm”, its cross section area in Inches², mm², and kcmil or MCM and resistance in ohms per 1000 feet and 1000 meter. The SWG size chart also shows the maximum capacity of current in amperes.

SWG	Diameter		Cross Section Area			Resistance in Ω		Max Current “A”
	inch	mm	inch2	mm2	kcmil	Ω / kft	Ω / km	Amp Capacity
7/0	0.500	12.700	0.1963	126.6769	250	0.0414	0.136	305.5
6/0	0.464	11.786	0.1691	109.0921	215	0.0481	0.158	264.8
5/0	0.432	10.973	0.1466	94.5638	187	0.0554	0.182	227.0
4/0	0.400	10.160	0.1257	81.0732	160	0.0647	0.213	196.3
3/0	0.372	9.449	0.1087	70.1202	138	0.0748	0.246	171.8
2/0	0.348	8.839	0.0951	61.3643	121	0.0854	0.281	148.9
0	0.324	8.230	0.0824	53.1921	105	0.0986	0.324	127.7
1	0.300	7.620	0.0707	45.6037	90.0	0.1150	0.378	108.1
2	0.276	7.010	0.0598	38.5989	76.2	0.1358	0.447	90.1
3	0.252	6.401	0.0499	32.1780	63.5	0.1629	0.536	76.4
4	0.232	5.893	0.0423	27.2730	53.8	0.1922	0.632	63.8
5	0.212	5.385	0.0353	22.7735	44.9	0.2302	0.757	52.3
6	0.192	4.877	0.0290	18.6793	36.9	0.2807	0.923	44.2
7	0.176	4.470	0.0243	15.6958	31.0	0.3340	1.10	33.3
8	0.160	4.064	0.0201	12.9717	25.6	0.4042	1.33	26.5
9	0.144	3.658	0.0163	10.5071	20.7	0.4990	1.64	21.2
10	0.128	3.251	0.0129	8.3019	16.4	0.6315	2.08	16.6
11	0.116	2.946	0.0106	6.8183	13.5	0.7689	2.53	13.6
12	0.104	2.642	0.0085	5.4805	10.8	0.9566	3.15	10.9
13	0.092	2.337	0.0066	4.2888	8.46	1.2224	4.02	8.58
14	0.080	2.032	0.0050	3.2429	6.40	1.6166	5.32	6.49
16	0.072	1.626	0.0041	2.0755	5.18	1.9958	6.56	5.25
15	0.064	1.829	0.0032	2.6268	4.10	2.5260	8.31	4.15
17	0.056	1.422	0.0025	1.5890	3.14	3.2992	10.9	3.18
18	0.048	1.219	0.0018	1.1675	2.30	4.4906	14.8	2.33
19	0.040	1.016	0.0013	0.8107	1.60	6.4665	21.3	1.62
20	0.036	0.914	0.0010	0.6567	1.30	7.9833	26.3	1.31
21	0.032	0.813	0.0008	0.5189	1.02	10.104	33.2	1.038
22	0.028	0.711	0.0006	0.3973	0.784	13.197	43.4	0.794
23	0.024	0.610	0.0005	0.2919	0.576	17.962	59.1	0.584
24	0.022	0.559	0.0004	0.2452	0.484	21.377	70.3	0.490
25	0.020	0.5080	0.0003	0.2027	0.400	25.866	85.1	0.405
26	0.018	0.4572	0.00025	0.1642	0.324	31.933	105	0.328
27	0.0164	0.4166	0.00021	0.1363	0.269	38.468	127	0.273
28	0.0148	0.3759	0.00017	0.1110	0.219	47.235	155	0.222
29	0.0136	0.3454	0.00014	0.0937	0.185	55.938	184	0.187
30	0.0124	0.3150	0.00012	0.0779	0.154	67.289	221	0.159
31	0.0116	0.2946	0.00010	0.0682	0.135	76.890	253	0.136
32	0.0108	0.2743	0.00009	0.0591	0.117	88.703	292	0.118
33	0.0100	0.2540	0.00008	0.0507	0.100	103.46	340	0.101
34	0.0092	0.2337	0.00007	0.0429	0.0846	122.24	402	0.086
35	0.0084	0.2134	0.00005	0.0358	0.0706	146.63	482	0.071
36	0.0076	0.1930	0.00004	0.0293	0.0578	179.13	589	0.0586
37	0.0068	0.1727	0.00003	0.0234	0.0462	223.75	736	0.0469
38	0.0060	0.1524	0.000028	0.0182	0.0360	287.39	945	0.036
39	0.0052	0.1321	0.000021	0.0137	0.0270	382.63	1260	0.027
40	0.0048	0.1219	0.00001809	0.0117	0.0230	449.06	1480	0.023
41	0.0044	0.1118	0.00001522	0.0098	0.0194	534.46	1760	0.019
42	0.004	0.1016	0.00001257	0.0081	0.0160	646.64	2130	0.016
43	0.0036	0.0914	0.00001017	0.0066	0.0130	798.33	2630	0.013
44	0.0032	0.0813	0.00000805	0.0052	0.0102	1010.38	3320	0.010
45	0.0028	0.0711	0.00000615	0.0040	0.00784	1319.68	4340	0.008
46	0.0024	0.0610	0.00000453	0.0029	0.00576	1796.24	5910	0.006
47	0.0020	0.0508	0.00000314	0.0020	0.00400	2586.58	8510	0.004
48	0.0016	0.0406	0.00000201	0.0013	0.00256	4041.53	13300	0.003
49	0.0012	0.0305	0.00000113	0.0007	0.00144	7184.95	23600	0.0015
50	0.0010	0.0254	0.00000078	0.0005	0.00100	10346.3	34000	0.001

Notes:

• The data for resistance of wires in Ω/km and Ω/kft are at 20°C or 68°F.
• The current capacity for copper wire are at 200A/cm²

Here is the SWG wire size chart in image format if you need to download it for later use.

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