Screw Thread Size and Tolerance Chart

Contents

What is a Screw Thread Size?

Screw sizes are determined by their major diameter and pitch. The major diameter is the largest screw diameter, and the pitch is the distance between adjacent thread points. Different measurement systems are used for thread size measurement, such as the Imperial system (Unified Thread Standard or UTS) in the U.S. and the metric system in most other countries. Identifying screw thread size depends on whether you’re dealing with metric or unified threads.

In the ANSI/ASME External Screw Thread Size Chart, all the dimensions and sizes are in inches.

Screw Thread Size & Tolerance Table

Screw Size	Class Thread	Major Diameter (Basic^a)	Major Diameter (Max.)	Major Diameter (Min.)	Pitch Diameter (Max.)	Pitch Diameter (Min.)	Minor Diameter (Max.)
0-80	2A	0.0600	0.0595	0.0563	0.0514	0.0496	0.0442
0-80	3A	0.0600	0.0600	0.0568	0.0519	0.0506	0.0447
1-64	2A	0.0730	0.0724	0.0686	0.0623	0.0603	0.0532
1-64	3A	0.0730	0.0730	0.0692	0.0629	0.0614	0.0538
1-72	2A	0.0730	0.0724	0.0689	0.0634	0.0615	0.0554
1-72	3A	0.0730	0.0730	0.0695	0.0640	0.0626	0.0560
2-56	2A	0.0860	0.0854	0.0813	0.0738	0.0717	0.0635
2-56	3A	0.0860	0.0860	0.0819	0.0744	0.0728	0.0641
2-64	2A	0.0860	0.0854	0.0816	0.0753	0.0733	0.0662
2-64	3A	0.0860	0.0860	0.0822	0.0759	0.0744	0.0668
3-48	2A	0.0990	0.0983	0.0938	0.0848	0.0825	0.0727
3-48	3A	0.0990	0.0990	0.0945	0.0855	0.0838	0.0734
3-56	2A	0.0990	0.0983	0.0942	0.0867	0.0845	0.0764
3-56	3A	0.0990	0.0990	0.0949	0.0874	0.0858	0.0771
4-40	2A	0.1120	0.1112	0.1061	0.0950	0.0925	0.0805
4-40	3A	0.1120	0.1120	0.1069	0.0958	0.0939	0.0813
4-48	2A	0.1120	0.1113	0.1068	0.0978	0.0954	0.0857
4-48	3A	0.1120	0.1120	0.1075	0.0985	0.0967	0.0864
5-40	2A	0.1250	0.1242	0.1191	0.1080	0.1054	0.0935
5-40	3A	0.1250	0.1250	0.1199	0.1088	0.1069	0.0943
5-44	2A	0.1250	0.1243	0.1195	0.1095	0.1070	0.0964
5-44	3A	0.1250	0.1250	0.1202	0.1102	0.1083	0.0971
6-32	2A	0.1380	0.1372	0.1312	0.1169	0.1141	0.0989
6-32	3A	0.1380	0.1380	0.1320	0.1177	0.1156	0.0997
6-40	2A	0.1380	0.1372	0.1321	0.1210	0.1184	0.1065
6-40	3A	0.1380	0.1380	0.1329	0.1218	0.1198	0.1073
8-32	2A	0.1640	0.1631	0.1571	0.1428	0.1399	0.1248
8-32	3A	0.1640	0.1640	0.1580	0.1437	0.1415	0.1257
8-36	2A	0.1640	0.1632	0.1577	0.1452	0.1424	0.1291
8-36	3A	0.1640	0.1640	0.1585	0.1460	0.1439	0.1299
10-24	2A	0.1900	0.1890	0.1818	0.1619	0.1586	0.1379
10-24	3A	0.1900	0.1900	0.1828	0.1629	0.1604	0.1389
10-32	2A	0.1900	0.1891	0.1831	0.1688	0.1658	0.1508
10-32	3A	0.1900	0.1900	0.1840	0.1697	0.1674	0.1517
1/4-20	2A	0.2500	0.2489	0.2408	0.2164	0.2127	0.1876
1/4-20	3A	0.2500	0.2500	0.2419	0.2175	0.2147	0.1887
1/4-28	2A	0.2500	0.2490	0.2425	0.2258	0.2225	0.2052
1/4-28	3A	0.2500	0.2500	0.2435	0.2268	0.2243	0.2062
5/16-18	2A	0.3125	0.3113	0.3026	0.2752	0.2712	0.2431
5/16-18	3A	0.3125	0.3125	0.3038	0.2764	0.2734	0.2443
5/16-24	2A	0.3125	0.3114	0.3042	0.2843	0.2806	0.2603
5/16-24	3A	0.3125	0.3125	0.3053	0.2854	0.2827	0.2614
3/8-16	2A	0.3750	0.3737	0.3643	0.3331	0.3287	0.2970
3/8-16	3A	0.3750	0.3750	0.3656	0.3344	0.3311	0.2983
3/8-24	2A	0.3750	0.3739	0.3667	0.3468	0.3430	0.3228
3/8-24	3A	0.3750	0.3750	0.3678	0.3479	0.3450	0.3239
7/16-14	2A	0.4375	0.4361	0.4258	0.3897	0.3850	0.3485
7/16-14	3A	0.4375	0.4375	0.4272	0.3911	0.3876	0.3499
7/16-20	2A	0.4375	0.4362	0.4281	0.4037	0.3995	0.3749
7/16-20	3A	0.4375	0.4375	0.4294	0.4050	0.4019	0.3762
1/2-13	2A	0.5000	0.4985	0.4876	0.4485	0.4435	0.4041
1/2-13	3A	0.5000	0.5000	0.4891	0.4500	0.4463	0.4056
1/2-20	2A	0.5000	0.4987	0.4906	0.4662	0.4619	0.4374
1/2-20	3A	0.5000	0.5000	0.4919	0.4675	0.4643	0.4387
9/16-12	2A	0.5625	0.5609	0.5495	0.5068	0.5016	0.4617
9/16-12	3A	0.5625	0.5609	0.5495	0.5068	0.5016	0.4617
9/16-14	2A	0.5625	0.5510	0.5507	0.5146	0.5096	0.4760
9/16-16	2A	0.5625	0.5611	0.5517	0.5205	0.5158	0.4866
9/16-16	3A	0.5625	0.5625	0.5531	0.5219	0.5184	0.4880
9/16-18	2A	0.5625	0.5611	0.5524	0.5250	0.5205	0.4950
9/16-18	3A	0.5625	0.5625	0.5538	0.5264	0.5230	0.4964
9/16-20	2A	0.5625	0.5612	0.5531	0.5287	0.5245	0.5017
9/16-20	3A	0.5625	0.5625	0.5544	0.5300	0.5268	0.5030
9/16-24	2A	0.5625	0.5613	0.5541	0.5342	0.5303	0.5117
9/16-24	3A	0.5625	0.5625	0.5553	0.5354	0.5325	0.5129
9/16-32	2A	0.5625	0.5615	0.5555	0.5412	0.5377	0.5243
9/16-32	3A	0.5625	0.5625	0.5565	0.5422	0.5396	0.5253
5/8-11	2A	0.6250	0.6234	0.6113	0.5644	0.5589	0.5119
5/8-11	3A	0.6250	0.6250	0.6129	0.5660	0.5619	0.5135
5/8-18	2A	0.6250	0.6236	0.6149	0.5875	0.5828	0.5554
5/8-18	3A	0.6250	0.6250	0.6163	0.5889	0.5854	0.5568
3/4-10	2A	0.7500	0.7482	0.7353	0.6832	0.6773	0.6255
3/4-10	3A	0.7500	0.7500	0.7371	0.6850	0.6806	0.6273
3/4-16	2A	0.7500	0.7485	0.7391	0.7079	0.7029	0.6718
3/4-16	3A	0.7500	0.7500	0.7406	0.7094	0.7056	0.6733
7/8-9	2A	0.8750	0.8731	0.8592	0.8009	0.7946	0.7368
7/8-9	3A	0.8750	0.8750	0.8611	0.8028	0.7981	0.7387
7/8-14	2A	0.8750	0.8734	0.8631	0.8270	0.8216	0.7858
7/8-14	3A	0.8750	0.8750	0.8647	0.8286	0.8245	0.7874
1-8	2A	1.0000	0.9980	0.9830	0.9168	0.9100	0.8446
1-8	3A	1.0000	1.0000	0.9850	0.9188	0.9137	0.8466
1-12	2A	1.0000	0.9982	0.9868	0.9441	0.9382	0.8960
1-12	3A	1.0000	1.0000	0.9886	0.9459	0.9415	0.8978
1-1/8-7	2A	1.1250	1.1228	1.1064	1.0300	1.0228	0.9475
1-1/8-12	2A	1.1250	1.1232	1.1118	1.0691	1.0631	1.0210
1-1/4-7	2A	1.2500	1.2478	1.2314	1.1550	1.1476	1.0725
1-1/4-12	2A	1.2500	1.2482	1.2368	1.1941	1.1879	1.1460
1-3/8-6	2A	1.3750	1.3726	1.3544	1.2643	1.2563	1.1681
1-3/8-12	2A	1.3750	1.3731	1.3617	1.3190	1.3127	1.2709
1-1/2-6	2A	1.5000	1.4976	1.4794	1.3893	1.3812	1.2931
1-1/2-12	2A	1.5000	1.4981	1.4867	1.4440	1.4376	1.3959
1-3/4-5	2A	1.7500	1.7473	1.7268	1.6174	1.6085	1.5019
2- 6	2A	2.0000	1.9971	1.9751	1.8528	1.8433	1.7245

Conclusion

That was all about the screw thread size chart. If you have any questions, make sure to write in comments.

What is a Screw Thread Size?

Screw Thread Size & Tolerance Table

Conclusion

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