Encyclopedia Magnetica™

Diameters of round enamelled wire according to IEC-60317-0-1

See also the main article: Enamelled wire.

The international standard IEC-60317-0-1 defines the preferred diameters of round enamelled wire as following the R20 series (20 sizes per decade).¹⁾ If intermediate values are required for technical reasons then they should follow the R40 series.

“Increase” denotes the difference between the outer and inner diameters.²⁾

Resistivity values are based on the nominal conductor diameter, with the nominal resistivity assumed as:³⁾
(1/58.5) Ω·mm²·m^-1 = 1.7094 × 10^-8 Ωm.

American Wire Gauge (AWG) sizes⁴⁾ are included for comparison and reference.

Ordinary enamelled wire

For wires below 0.08 mm the resistance can vary up to around ±10%, for wires up 0.28 mm the variation reduces gradually to ±4%, and for thicker wires it is around ±3%.

These variation in resistance arise from the combined allowed tolerances on resistivity and conductor diameter.

Nominal conductor diameter (mm)	Conductor tolerance +/- (mm)	Min. increase due to the insulation (mm)			Max. outer diameter (mm)			Nominal resistance at 20 °C (Ω/m)	Nearest AWG size
Nominal conductor diameter (mm)	Conductor tolerance +/- (mm)	Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3	Nominal resistance at 20 °C (Ω/m)	Nearest AWG size
0.018		0.002	0.004	0.006	0.022	0.024	0.026	67.18	53 AWG
0.020		0.002	0.004	0.007	0.024	0.027	0.030	54.41	52 AWG
0.022		0.002	0.005	0.008	0.027	0.030	0.033	44.97	51 AWG
0.025		0.003	0.005	0.008	0.031	0.034	0.037	34.82	50 AWG
0.028		0.003	0.006	0.009	0.034	0.038	0.042	27.76	49 AWG

0.032		0.003	0.007	0.010	0.039	0.043	0.047	21.25	48 AWG
0.036		0.004	0.008	0.011	0.044	0.049	0.053	16.79	47 AWG
0.040		0.004	0.008	0.012	0.049	0.054	0.058	13.60	46 AWG
0.045		0.005	0.009	0.013	0.055	0.061	0.066	10.75	45 AWG
0.050		0.005	0.010	0.014	0.060	0.066	0.072	8.706	44 AWG

0.056		0.006	0.011	0.015	0.067	0.074	0.081	6.940	43 AWG
0.063		0.006	0.012	0.017	0.076	0.083	0.090	5.484	42 AWG
0.071	0.003	0.007	0.012	0.018	0.084	0.091	0.098	4.318	41 AWG
0.080	0.003	0.007	0.014	0.020	0.094	0.101	0.108	3.401	40 AWG
0.090	0.003	0.008	0.015	0.022	0.105	0.113	0.120	2.687	39 AWG

0.100	0.003	0.008	0.016	0.023	0.117	0.125	0.132	2.176	38 AWG
0.112	0.003	0.009	0.017	0.026	0.130	0.139	0.147	1.735	37 AWG
0.125	0.003	0.010	0.019	0.028	0.144	0.154	0.163	1.393	36 AWG
0.140	0.003	0.011	0.021	0.030	0.160	0.171	0.181	1.110	35 AWG
0.160	0.003	0.012	0.023	0.033	0.182	0.194	0.205	0.8502	34 AWG

0.180	0.003	0.013	0.025	0.036	0.204	0.217	0.229	0.6718	33 AWG
0.200	0.003	0.014	0.027	0.039	0.226	0.239	0.252	0.5441	32 AWG
0.224	0.003	0.015	0.029	0.043	0.252	0.266	0.280	0.4338	31 AWG
0.250	0.004	0.017	0.032	0.048	0.281	0.297	0.312	0.3482	30 AWG
0.280	0.004	0.018	0.033	0.050	0.312	0.329	0.345	0.2776	29 AWG

0.315	0.004	0.019	0.035	0.053	0.349	0.367	0.384	0.2193	28 AWG
0.355	0.004	0.020	0.038	0.057	0.392	0.411	0.428	0.1727	27 AWG
0.400	0.005	0.021	0.040	0.060	0.439	0.459	0.478	0.1360	26 AWG
0.450	0.005	0.022	0.042	0.064	0.491	0.513	0.533	0.1075	25 AWG
0.500	0.005	0.024	0.045	0.067	0.544	0.566	0.587	0.08706	24 AWG

0.560	0.006	0.025	0.047	0.071	0.606	0.630	0.653	0.06940	23 AWG
0.630	0.006	0.027	0.050	0.075	0.679	0.704	0.728	0.05484	22 AWG
0.710	0.007	0.028	0.053	0.080	0.762	0.789	0.814	0.04318	21 AWG
0.800	0.008	0.030	0.056	0.085	0.855	0.884	0.911	0.03401	20 AWG
0.900	0.009	0.032	0.060	0.090	0.959	0.989	1.018	0.02687	19 AWG

1.000	0.010	0.034	0.063	0.095	1.062	1.094	1.124	0.02176	18 AWG
1.120	0.011	0.034	0.065	0.098	1.184	1.217	1.248	0.01735	17 AWG
1.250	0.013	0.035	0.067	0.100	1.316	1.349	1.381	0.01393	16 AWG
1.400	0.014	0.036	0.069	0.103	1.468	1.502	1.535	0.01110	15 AWG
1.600	0.016	0.038	0.071	0.107	1.670	1.706	1.740	0.008502	14 AWG

1.800	0.018	0.039	0.073	0.110	1.872	1.909	1.944	0.006718	13 AWG
2.000	0.020	0.040	0.075	0.113	2.074	2.112	2.148	0.005441	12 AWG
2.240	0.022	0.041	0.077	0.116	2.316	2.355	2.392	0.004338	11 AWG
2.500	0.025	0.042	0.079	0.119	2.578	2.618	2.656	0.003482	10 AWG
2.800	0.028	0.043	0.081	0.123	2.880	2.922	2.961	0.002776	9 AWG

3.150	0.032	0.045	0.084	0.127	3.233	3.276	3.316	0.002193	8 AWG
3.550	0.036	0.046	0.086	0.130	3.635	3.679	3.721	0.001727	7 AWG
4.000	0.040	0.047	0.089	0.134	4.088	4.133	4.176	0.001360	6 AWG
4.500	0.045	0.049	0.092	0.138	4.591	4.637	4.681	0.001075	5 AWG
5.000	0.050	0.050	0.094	0.142	5.093	5.141	5.186	0.0008706	4 AWG

Enamelled wire with a bonding layer

Nominal conductor diameter (mm)	Conductor tolerance +/- (mm)	Min. increase due to the underlying coating (mm)		Min. increase due to bonding layer (mm)	Max. overall diameter (mm)		Nearest AWG size
Nominal conductor diameter (mm)	Conductor tolerance +/- (mm)	Grade 1B	Grade 2B	Min. increase due to bonding layer (mm)	Grade 1B	Grade 2B	Nearest AWG size
0.020		0.002	0.004	0.002	0.026	0.029	52 AWG
0.022		0.002	0.005	0.002	0.030	0.033	51 AWG
0.025		0.003	0.005	0.002	0.034	0.037	50 AWG
0.028		0.003	0.006	0.003	0.038	0.042	49 AWG
0.032		0.003	0.007	0.003	0.044	0.048	48 AWG

0.036		0.004	0.008	0.003	0.050	0.055	47 AWG
0.040		0.004	0.008	0.003	0.055	0.060	46 AWG
0.045		0.005	0.009	0.003	0.062	0.068	45 AWG
0.050		0.005	0.010	0.003	0.068	0.074	44 AWG
0.056		0.006	0.011	0.003	0.075	0.082	43 AWG

0.063		0.006	0.012	0.005	0.085	0.092	42 AWG
0.071	0.003	0.007	0.012	0.005	0.094	0.101	41 AWG
0.080	0.003	0.007	0.014	0.005	0.105	0.112	40 AWG
0.090	0.003	0.008	0.015	0.005	0.117	0.125	39 AWG
0.100	0.003	0.008	0.016	0.005	0.129	0.137	38 AWG

0.112	0.003	0.009	0.017	0.008	0.143	0.152	37 AWG
0.125	0.003	0.010	0.019	0.009	0.158	0.168	36 AWG
0.140	0.003	0.011	0.021	0.010	0.175	0.186	35 AWG
0.160	0.003	0.012	0.023	0.010	0.197	0.209	34 AWG
0.180	0.003	0.013	0.025	0.010	0.220	0.233	33 AWG

0.200	0.003	0.014	0.027	0.011	0.243	0.256	32 AWG
0.224	0.003	0.015	0.029	0.012	0.270	0.284	31 AWG
0.250	0.004	0.017	0.032	0.013	0.300	0.316	30 AWG
0.280	0.004	0.018	0.033	0.013	0.331	0.348	29 AWG
0.315	0.004	0.019	0.035	0.014	0.369	0.387	28 AWG

0.355	0.004	0.020	0.038	0.015	0.413	0.432	27 AWG
0.400	0.005	0.021	0.040	0.016	0.461	0.481	26 AWG
0.450	0.005	0.022	0.042	0.016	0.514	0.536	25 AWG
0.500	0.005	0.024	0.045	0.017	0.568	0.590	24 AWG
0.560	0.006	0.025	0.047	0.017	0.630	0.654	23 AWG

0.630	0.006	0.027	0.050	0.018	0.704	0.729	22 AWG
0.710	0.007	0.028	0.053	0.019	0.788	0.815	21 AWG
0.800	0.008	0.030	0.056	0.020	0.882	0.911	20 AWG
0.900	0.009	0.032	0.060	0.020	0.987	1.017	19 AWG
1.000	0.010	0.034	0.063	0.021	1.091	1.123	18 AWG

1.120	0.011	0.034	0.065	0.022	1.214	1.247	17 AWG
1.250	0.013	0.035	0.067	0.022	1.346	1.379	16 AWG
1.400	0.014	0.036	0.069	0.023	1.499	1.533	15 AWG
1.600	0.016	0.038	0.071	0.023	1.702	1.738	14 AWG
1.800	0.018	0.039	0.073	0.024	1.905	1.942	13 AWG

2.000	0.020	0.040	0.075	0.025	2.108	2.146	12 AWG

Enamelled wire, Windings, Magnet wire, Copper wire, Wire size, AWG, American wire gage, American wire gauge, Counter

^1),
3) IEC 60317-0-1:2013+AMD1:2019 CSV, Consolidated version, Specifications for particular types of winding wires - Part 0-1: General requirements - Enamelled round copper wire, {accessed 2021-11-27}

²⁾ DASOL, Round enamelled winding wire of copper, solderable, class 180, Product information, {accessed 2021-11-27}

⁴⁾ ASTM B 258-02, Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors, {accessed 2021-11-27}