Wire Gauge Comparison Chart

There have been many times in my life when I have been confused by references in literature to wire gauges that may be common in some places, but are not universal. Some of these occasions have been very significant and could have led to serious problems and consequences. I have spent much of my life designing unusual custom built electrical and electronic control gear and errors due to wrong wire gauge could have caused fire or failure.

As long ago as 1961 I decided to produce a chart to convert 'Birmingham' wire gauge (BWG) to 'Standard' wire gauge (SWG), but I never completed it. In the early 1960s I spent some time as a transformer designer and had a battery of 'ready reckoners' at my disposal. In the early 1970s I was designing electrical equipment and came across 'American' wire gauge (AWG) for which I had a 'crib sheet' to convert to the more normal (and more useful) cross sectional area figures.

I have finally got round to attempting a 'once and for all' version that is posted on the web for anybody to peruse. I have made use of many reference sources, but the major ones are listed at the page bottom. I have also had help from various surfers that have pointed out errors, for which I am eternally grateful... A project of this nature can be rather intense and it is difficult to see some errors when you are so close to the mechanics of producing the page. In the May 2006 revision I have introduced different background colours to alternate rows, which helps the eye to track across the page, in order to help keep track of columns, the November 2006 revision has coloured the Birmingham or Stubs column yellow.

The list is based on decreasing diameters and cross sectional areas. This approach leads to a number of gaps in places and a few extra rows in the table, but the decreasing size of the conductors gives a better visual indication of the relation between the systems involved and their related current carrying capacity.

I have included drill sizes in this chart for two reasons... Occasionally it is important to drill a hole that is a good fit on a wire for soldering purposes or for clearance purposes. Some drill blanks are used as rods in some mechanical engineering designs. Number and Letter drills are the post 1959 rationalised ones.

The diameters stated are for solid single bare wires... If you need to know the finished diameter of an insulated wire you must consult the manufacturer concerned as all manufacturers differ on this factor. If in doubt measure the actual material with a micrometer or us a gauge plate as illustrated at right. Some ideas for using the gauge plate to measure or at least estimate insulation thickness as well as instructions for use are given at the page bottom. There are some notes on insulation of winding wires on the ???[future page].

Whilst every attempt has been made to ensure the accuracy of the figures tabulated, they may not be perfect, if anyone has any information that conflicts with the chart, even if this is merely a difference in the last decimal place, please contact me by Email using the button at the page bottom, and I will try to rectify or rationalise the situation.

There are other existing gauges and, if accurate information exists, I would be prepared to add them to this chart.

Where there are large numbers of decimal places quoted this does not imply extreme precision. I have left such figures intact rather than truncating them, please use common sense in deciding the significance or precision that you wish to work to. In general four significant figures is adequate for most industrial and engineering purposes.

* The gauge sizes of hypodermic syringe needles is the same as 'Birmingham or Stubs' Wire Gauge.

SWG = Standard Wire Gauge	W & M = Washburn & Moen
AWG = American Wire Gauge or Brown & Sharpe, (B & S)	BWG = Birmingham Wire Gauge or Stubs' Wire Gauge

Diameter mm	Diameter Inches	Cross Sectional Area mm²	SWG	BWG or Stubs*	W & M	AWG or B & S	No. or Letter Drill	Inch Fraction Drill
14.732	0.5800	170.45625				6/0
13.1191	0.5165	135.1754				5/0
12.70	0.5000	126.6767	0000000	5/0				1/2
12.446	0.4900	121.660			7/0
12.303	0.4844	118.9						31/64
11.90	0.4688	111.36						15/32
11.7856	0.464	109.092	000000
11.7221	0.4615	107.92			6/0
11.684	0.4600	107.219				4/0
11.5316	0.454	104.452		4/0
11.508	0.4531	104.03						29/64
11.11	0.4375	96.99						7/16
10.9728	0.432	94.5637	00000
10.9347	0.4305	93.908			5/0
10.795	0.425	91.524		3/0
10.72	0.4219	90.19						27/64
10.50	0.4134	86.590					Z
10.40384	0.4096	85.01				3/0
10.3175	0.4062	83.60						13/32
10.30	0.4055	83.32					Y
10.160	0.400	81.073	0000
10.10	0.3976	80.12					X
10.00252	0.3938	78.54			4/0
9.92	0.3906	77.30						25/64
9.652	0.380	73.168		2/0
9.525	0.3750	71.26					V	3/8
9.4488	0.372	70.12	000
9.30	0.3661	67.93					U
9.26592	0.3648	67.432				2/0
9.2075	0.3625	66.58			3/0
9.129	0.3594	65.45						23/64
9.10	0.3583	65.04					T
8.8392	0.348	61.36	00
8.80	0.3465	60.82					S
8.73	0.3438	59.89						11/32
8.636	0.340	58.58		1/0
8.60	0.3386	58.09					R
8.4074	0.3310	55.52			2/0
8.400	0.3307	55.42					Q
8.25246	0.3249	53.49				1/0
8.23	0.3240	53.19	0
8.20	0.3228	52.81					P	21/64
8.00	0.315	50.27					O
7.9375	0.3125	49.483						5/16
7.7851	0.3065	47.60			1/0
7.70	0.3031	46.57					N
7.62	0.3000	45.60	1	1
7.541	0.2969	44.666						19/64
7.50	0.2953	44.18					M
7.40	0.2913	43.00					L
7.348	0.2893	42.41				1
7.2136	0.284	40.87		2
7.188	0.2830	40.58			1
7.142	0.2812	40.07					K	9/32
7.01	0.276	38.59	2
7.00	0.2756	38.48					J
6.90	0.2717	37.39					I
6.746	0.2656	35.74					H	17/64
6.667	0.2625	34.92			2
6.60	0.2598	34.21					G
6.579	0.259	33.99		3
6.543	0.2576	33.62				2
6.50	0.2559	33.18					F
6.40	0.252	32.17	3
6.350	0.250	31.67					E	1/4
6.20	0.2441	30.19					D
6.19	0.2437	30.09			3
6.10	0.2402	29.22					C
6.045	0.238	28.70		4
6.00	0.2362	28.27					B
5.94	0.2344	27.84					A	15/64
5.89	0.232	27.25	4
5.827	0.2294	26.66				3
5.8	0.2283	26.42					1
5.723	0.2253	25.72			4
5.588	0.220	24.52		5			2
5.55625	0.21875	24.246						7/32
5.38	0.212	22.73	5				3
5.30	0.2087	22.06					4
5.258	0.2070	21.71			5
5.20	0.2047	21.237					5 or 6*
5.189	0.2043	21.15				4
5.156	0.203	20.88		6				13/64
5.10	0.2008	20.428					7 or 8*
5.00	0.1968	19.635					9
4.90	0.1929	18.857					10 or 11*
4.88	0.192	18.70	6		6
4.80	0.189	18.095					11
4.7625	0.1875	17.81						3/16
4.70	0.185	17.349					13
4.62	0.1819	16.76385				5	14
4.572	0.180	16.42		7			15
4.496	0.1770	15.875			7		16
4.47	0.176	15.69	7
4.40	0.1732	15.20					17
4.366	0.1719	14.97						11/64
4.30	0.1693	14.52					18
4.19	0.165	13.795		8			19
4.115	0.162	13.298			8	6
4.10	0.1614	13.20					20
4.06	0.160	12.95	8
4.00	0.1575	12.566					21 or 22*
3.969	0.15625	12.370						5/32
3.90	0.1535	11.946					23 or 24*
3.80	0.1496	11.34					25
3.76	0.148	11.099		9	9
3.7338	0.147	10.949					26
3.66	0.144	10.52	9			7	27
3.57	0.1406	10.02					28	9/64
3.50	0.1378	9.62					29
3.429	0.1350	9.23			10
3.40	0.134	9.098		10
3.30	0.1299	8.553					30
3.25	0.128	8.296	10			8
3.175	0.125	7.917						1/8
3.048	0.120	7.2966		11	11
3.00	0.1181	7.068					31
2.95	0.116	6.835	11				32
2.90	0.1144	6.63				9
2.85	0.1122	6.379					33
2.80	0.1102	6.153					34 or 35*
2.769	0.109	6.020		12				7/64
2.70	0.1063	5.725					36
2.68	0.1055	5.64			12
2.64	0.104	5.474	12				37
2.60	0.1024	5.31					38
2.586	0.1018	5.25				10
2.55	0.1004	5.10					39
2.50	0.0984	4.90					40
2.45	0.0965	4.71					41
2.413	0.095	4.573		13
2.38	0.0938	4.458					42	3/32
2.34	0.092	4.300	13
2.324	0.0915	4.242			13
2.30	0.0907	4.168				11
2.257	0.08885	4.00					43
2.20	0.0866	3.80					44
2.108	0.083	3.490		14
2.10	0.0827	3.46					45
2.05	0.0807	3.300					46
2.03	0.080	3.237	14		14	12
2.00	0.0787	3.14159					47
1.98	0.0781	3.090						5/64
1.95	0.0768	2.986					48
1.85	0.0728	2.688					49
1.83	0.072	2.630	15	15	15	13
1.784	0.0702	2.50					50
1.70	0.0669	2.269					51
1.651	0.065	2.14		16
1.63	0.064	2.086	16			14
1.60	0.063	2.011					52
1.5875	0.0625	1.98			16			1/16
1.50	0.059	1.767					53
1.473	0.058	1.70		17
1.448	0.0570	1.646				15
1.42	0.056	1.584	17
1.40	0.055	1.539					54
1.382	0.0544	1.50			17
1.30	0.0512	1.327					55
1.290	0.0508	1.30				16
1.2446	0.049	1.2166		18
1.22	0.048	1.169	18
1.2065	0.0475	1.143			18
1.181	0.0465	1.0956					56	3/64
1.148	0.0452	1.035				17
1.128	0.0444	1.00
1.10	0.0433	0.950					57
1.067	0.042	0.8938		19			58
1.041	0.041	0.852			19		59
1.02	0.040	0.8171	19			18	60
1.000	0.0394	0.787					61
0.98	0.0386	0.754					62
0.95	0.0374	0.709					63
0.9144	0.036	0.6567	20			19	64
0.889	0.035	0.6207		20			65
0.8839	0.0348	0.614			20
0.850	0.0335	0.569					66
0.813	0.032	0.519	21	21			67
0.810	0.0319	0.5156			21	20
0.79	0.0312	0.490					68	1/32
0.75	0.0295	0.442					69
0.71112	0.028	0.3973	22	22	22	21	70
0.660	0.026	0.3425			23		71
0.635	0.025	0.3167		23		22	72
0.610	0.024	0.2922	23				73
0.579	0.0228	0.2634			24		74
0.5715	0.0225	0.2565				23
0.5588	0.022	0.2453	24	24
0.52	0.0205	0.21237					75
0.508	0.020	0.2027	25	25	25	24	76
0.4572	0.018	0.16417	26	26	26
0.45466	0.0179	0.162354				25
0.450	0.0177	0.1590					77
0.44168	0.01739	0.1532				25.25
0.439	0.0173	0.152			27
0.42906	0.01689	0.14458				25.5
0.417	0.0164	0.1366	27		28	25.75
0.406	0.016	0.1297		27
0.40386	0.0159	0.1281				26
0.3988	0.0157	0.1249					78
0.396	0.0156	0.1232						1/64
0.39332	0.01549	0.12150				26.25
0.38209	0.01504	0.11466				26.5
0.378	0.0149	0.111			29		79
0.3759	0.0148	0.1109	28
0.37117	0.01461	0.10820				26.75
0.36068	0.0142	0.10215				27
0.3569	0.01405	0.1000		28	30
0.35027	0.01379	0.09636				27.25
0.345	0.0136	0.0935	29				80
0.34026	0.01340	0.09093				27.5
0.330	0.013	0.0856		29	31	27.75
0.325	0.0128	0.0830			32
0.3200	0.0126	0.0805				28
0.3150	0.0124	0.07791	30
0.31192	0.01228	0.07641				28.25
0.3048	0.0120	0.073		30
0.30301	0.01193	0.07211				28.5
0.2998	0.0118	0.07055			33
0.295	0.0116	0.06835	31			28.75
0.2870	0.0113	0.064696				29
0.27777	0.01094	0.060598				29.25
0.2743	0.0108	0.05910	32
0.26984	0.01062	0.05719				29.5
0.2641	0.0104	0.05480			34
0.26213	0.01032	0.053966				29.75
0.254	0.0100	0.05067	33	31		30
0.24736	0.00974	0.04805				30.25
0.2413	0.0095	0.04573			35
0.24030	0.00946	0.45352				30.5
0.2337	0.0092	0.04289	34			30.75
0.2260	0.0089	0.0401		32	36	31
0.22028	0.00867	0.0381				31.25
0.213	0.0084	0.03563	35		37	31.5
0.20788	0.00818	0.03394				31.75
0.2032	0.0080	0.03243				32
0.200	0.0079	0.03162		33	38
0.19617	0.00772	0.03022				32.25
0.1930	0.0076	0.02927	36		39
0.19056	0.00750	0.02852				32.5
0.18512	0.00729	0.0269				32.75
0.1803	0.0071	0.02554				33
0.1778	0.0070	0.0248		34	40
0.17469	0.00688	0.02397				33.25
0.173	0.0068	0.0235	37
0.16970	0.00668	0.0226				33.5
0.1676	0.0066	0.02207			41
0.16485	0.00649	0.02134				33.75
0.1600	0.0063	0.020			42	34
0.15557	0.00612	0.01900				34.25
0.1524	0.0060	0.018241	38		43
0.15112	0.00595	0.01794				34.5
0.1473	0.0058	0.0170			44	34.75
0.142	0.0056	0.01589			45	35
0.13854	0.00545	0.01507				35.25
0.13458	0.00530	0.01422				35.5
0.132	0.0052	0.013685	39		46
0.13074	0.00515	0.013425				35.75
0.127	0.0050	0.0127		35	47	36
0.1219	0.0048	0.011675	40		48
0.11985	0.00472	0.01128				36.5
0.1168	0.0046	0.01072			49
0.1143	0.0045	0.01026				37
0.112	0.0044	0.00985	41		50
0.10673	0.00420	0.00895				37.5
0.102	0.0040	0.00817	42	36		38
0.09504	0.00374	0.00709				38.5
0.091	0.0036	0.00650	43
0.0889	0.0035	0.006207				39
0.08464	0.00333	0.005626				39.5
0.081	0.0032	0.005153	44
0.07874	0.0031	0.004869				40
0.071	0.0028	0.003959	45			41
0.0636	0.0025	0.003167				42
0.061	0.0024	0.002922	46
0.0564	0.00222	0.0025				43
0.051	0.0020	0.00204	47			44
0.0447	0.00176	0.00157				45
0.041	0.0016	0.00132	48
0.039878	0.00157	0.001249				46
0.03556	0.00140	0.000993				47
0.0315	0.00124	0.000779				48
0.030	0.0012	0.000707	49
0.282	0.00111	0.000624				49
0.025	0.0010	0.000491	50			50
0.022	0.00088	0.000392				51
0.0198	0.00078	0.000308				52
0.0178	0.00070	0.000248				53
0.0157	0.00062	0.000195				54
0.014	0.00055	0.000153				55
0.0125	0.00049	0.000122				56

Circular mils... There was a system in use many years ago, that is still apparently used in USA, I have been asked to include it in the chart, but rather than clutter what is already there with a minority system, I will explain how the property is derived.

Wire Gauge Comparison Chart

Written... 19-26 April 2002, Completed... 26 May 2002, Correction (0.3569)... 01 October 2002, New Domain 12 April 2004, Upgraded With Revisions to AWG 5, 25, 27, 29, 32, 33, 37, 39, 40, 42, 46... 07 May 2006, Correction to 33 G W& M CSA... 27 October 2006, Several Corrections... 29 November 2006,