Imperial Threads

The charts below gives the dimensions for BA, BSF, BSW ,BSPP and BSPT Threads.

Dimensions shown are in mm and Inches, if you wish to convert them please use our universal converter.

Designation	Pitch (mm)	Major Diameter		Pitch (in)	Depth of Thread		Effective Diameter		Minor Diameter
Designation	Pitch (mm)	(in)	(mm)	Pitch (in)	(in)	(mm)	(in)	(mm)	(in)	(mm)
0 BA	1.00	0.2362	6.00	0.0394	0.0236	0.60	0.2126	5.40	0.1890	4.80
1 BA	0.90	0.2087	5.30	0.0354	0.0213	0.54	0.1874	4.76	0.1661	4.22
2 BA	0.81	0.1850	4.70	0.0319	0.0191	0.49	0.1659	4.21	0.1469	3.73
3 BA	0.73	0.1614	4.10	0.0287	0.0172	0.44	0.1442	3.66	0.1270	3.22
4 BA	0.66	0.1417	3.60	0.0260	0.0156	0.40	0.1261	3.20	0.1105	2.81
5 BA	0.59	0.1260	3.20	0.0232	0.0139	0.35	0.1121	2.85	0.0982	2.50
6 BA	0.53	0.1102	2.80	0.0209	0.0125	0.32	0.0977	2.48	0.0852	2.16
7 BA	0.48	0.0984	2.50	0.0189	0.0113	0.29	0.0871	2.21	0.0758	1.92
8 BA	0.43	0.0866	2.20	0.0169	0.0102	0.26	0.0764	1.94	0.0661	1.68
9 BA	0.39	0.0748	1.90	0.0154	0.0092	0.23	0.0656	1.67	0.0563	1.43
10 BA	0.35	0.0669	1.70	0.0138	0.0083	0.21	0.0586	1.49	0.0503	1.28
11 BA	0.31	0.0591	1.50	0.0122	0.0073	0.19	0.0518	1.31	0.0445	1.13
12 BA	0.28	0.0512	1.30	0.0110	0.0066	0.17	0.0446	1.13	0.0380	0.097

Nominal Size (in)	Threads Per Inch (TPI)	Major Diameter		Pitch		Effective Diameter		Minor Diameter (Core)
Nominal Size (in)	Threads Per Inch (TPI)	(in)	(mm)	(in)	(mm)	(in)	(mm)	(in)	(mm)
3/16	32	0.1875	4.763	0.0313	0.794	0.1675	4.255	0.1475	3.747
7/32	28	0.2188	5.556	0.0357	0.907	0.1959	4.976	0.1730	4.394
1/4	26	0.2500	6.350	0.0385	0.977	0.2254	5.725	0.2008	5.100
5/16	22	0.3125	7.938	0.0455	1.155	0.2834	7.198	0.2543	6.459
3/8	20	0.3750	9.525	0.0500	1.270	0.3430	8.712	0.3110	7.900
7/16	18	0.4375	11.113	0.0556	1.411	0.4019	10.208	0.3664	9.307
1/2	16	0.5000	12.700	0.0625	1.588	0.4600	11.684	0.4200	10.668
9/16	16	0.5625	14.288	0.0625	1.588	0.5225	13.272	0.4825	12.256
5/8	14	0.6250	15.875	0.0714	1.814	0.5793	14.714	0.5336	13.553
11/16	14	0.6875	17.463	0.0714	1.814	0.6418	16.302	0.5961	15.141
3/4	12	0.7500	19.050	0.0833	2.117	0.6966	17.694	0.6433	16.340
7/8	11	0.8750	22.225	0.0909	2.309	0.8168	20.747	0.7586	19.269
1	10	1.0000	25.400	0.1000	2.540	0.9360	23.774	0.8720	22.149

Nominal Size (in)	Threads Per Inch (TPI)	Major Diameter		Pitch		Effective Diameter		Minor Diameter (Core)
Nominal Size (in)	Threads Per Inch (TPI)	(in)	(mm)	(in)	(mm)	(in)	(mm)	(in)	(mm)
1/16	60	0.0625	1.588	0.0167	0.423	0.0518	1.316	0.0411	1.044
3/32	48	0.0938	2.381	0.0208	0.529	0.0804	2.042	0.0672	1.707
1/8	40	0.1250	3.175	0.0250	0.635	0.1090	2.769	0.0930	2.362
5/32	32	0.1563	3.969	0.0313	0.794	0.1363	3.462	0.1163	2.954
3/16	24	0.1875	4.763	0.0417	1.058	0.1608	4.084	0.1341	3.406
7/32	24	0.2188	5.556	0.0417	1.058	0.1921	4.879	0.1654	4.201
1/4	20	0.2500	6.350	0.0500	1.270	0.2180	5.537	0.1860	4.724
5/16	18	0.3125	7.938	0.0556	1.411	0.2769	7.033	0.2414	6.132
3/8	16	0.3750	9.525	0.0625	1.588	0.3350	8.509	0.2950	7.493
7/16	14	0.4375	11.113	0.0714	1.814	0.3918	9.952	0.3461	8.791
1/2	12	0.5000	12.700	0.0833	2.117	0.4466	11.344	0.3933	9.990
5/8	11	0.6250	15.875	0.0909	2.309	0.5668	14.397	0.5086	12.918
3/4	10	0.7500	19.050	0.1000	2.540	0.6860	17.424	0.6220	15.799
7/8	9	0.8750	22.225	0.1111	2.822	0.8039	20.419	0.7328	18.613
1	8	1.0000	25.400	0.1250	3.175	0.9200	23.368	0.8400	21.336

Gauge Size	Threads Per Inch (TPI)	Pitch		Major Diameter		Effective Diameter		Minor Diameter
Gauge Size	Threads Per Inch (TPI)	(in)	(mm)	(in)	(mm)	(in)	(mm)	(in)	(mm)
G 1/16	28	0.0357	0.907	0.3040	7.723	0.2811	7.142	0.2583	6.561
G 1/8	28	0.0357	0.907	0.3830	9.728	0.3601	9.147	0.3373	8.566
G 1/4	19	0.0526	1.337	0.5180	13.157	0.4843	12.301	0.4506	11.445
G 3/8	19	0.0526	1.337	0.6560	16.662	0.6223	15.806	0.5886	14.950
G 1/2	14	0.0714	1.814	0.8250	20.955	0.7793	19.793	0.7336	18.631
G 5/8	14	0.0714	1.814	0.9020	22.911	0.8563	21.749	0.8106	20.587
G 3/4	14	0.0714	1.814	1.0410	26.441	0.9953	25.279	0.9496	24.117
G 7/8	14	0.0714	1.814	1.1890	30.201	1.1433	29.039	1.0976	27.877
G 1	11	0.0909	2.309	1.3090	33.249	1.2508	31.770	1.1926	30.291
G 1-1/4	11	0.0909	2.309	1.6500	41.910	1.5918	40.431	1.5336	38.952
G 1-1/2	11	0.0909	2.309	1.8820	47.803	1.8238	46.324	1.7656	44.845
G 2	11	0.0909	2.309	2.3470	59.614	2.2888	58.135	2.2306	56.656

Nominal Size	Threads Per Inch (TPI)	Pitch		Major Diameter at Gauge Plane		Gauge Length		Fitting Allowance (Turns)
Nominal Size	Threads Per Inch (TPI)	(in)	(mm)	(in)	(mm)	(in)	(mm)	Fitting Allowance (Turns)
1/16	28	0.0357	0.907	0.304	7.723	0.157	4.0	4.4
1/8	28	0.0357	0.907	0.383	9.728	0.157	4.0	4.4
1/4	19	0.0526	1.337	0.518	13.157	0.237	6.0	4.5
3/8	19	0.0526	1.337	0.656	16.662	0.252	6.4	4.8
1/2	14	0.0714	1.814	0.825	20.955	0.322	8.2	4.5
3/4	14	0.0714	1.814	1.041	26.441	0.374	9.5	5.2
1	11	0.0909	2.309	1.309	33.249	0.409	10.4	4.5
1-1/4	11	0.0909	2.309	1.650	41.910	0.500	12.7	5.5
1-1/2	11	0.0909	2.309	1.882	47.803	0.500	12.7	5.5
2	11	0.0909	2.309	2.347	59.614	0.626	15.9	6.9

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