{"id":14565,"date":"2025-03-24T14:34:47","date_gmt":"2025-03-24T19:34:47","guid":{"rendered":"https:\/\/blog.misumiusa.com\/?page_id=14565"},"modified":"2025-03-24T15:55:51","modified_gmt":"2025-03-24T20:55:51","slug":"screw-threads-size-chart","status":"publish","type":"page","link":"https:\/\/us.misumi-ec.com\/blog\/screw-threads-size-chart\/","title":{"rendered":"External Screw Threads Size and Tolerances"},"content":{"rendered":"\n

Author: Scott Bredemann<\/a><\/p>\n\n\n\n

Updated<\/strong>: 03\/24\/2025 | Read Time<\/strong>: 3mins<\/p>\n\n\n\n

The American National Standards Institute (ANSI) sets guidelines for external screw threads, specifying dimensions and tolerances based on thread class (2A and 3A). These standards help engineers and manufacturers maintain consistency, reduce wear, and improve performance across various industrial and commercial uses.<\/p>\n\n\n\n

This guide provides a detailed table of ANSI external screw thread sizes, covering major, pitch, and minor diameters along with their tolerances.<\/p>\n\n\n\n

Screw Size<\/strong><\/td>Thread Class<\/strong><\/td>Major Diameter<\/strong><\/td>Major Diameter<\/strong><\/td>Major Diameter<\/strong><\/td>Pitch Diameter<\/strong><\/td>Pitch Diameter<\/strong><\/td>Minor Diameter<\/strong><\/td><\/tr>
<\/td><\/td>Basic<\/strong><\/td>Max<\/strong><\/td>Min<\/strong><\/td>Max<\/strong><\/td>Min<\/strong><\/td>Min<\/strong><\/td><\/tr>
0-80<\/td>2A<\/td>0.06<\/td>0.0605<\/td>0.0595<\/td>0.0518<\/td>0.0506<\/td>0.0455<\/td><\/tr>
0-80<\/td>3A<\/td>0.06<\/td>0.0603<\/td>0.0597<\/td>0.0523<\/td>0.0511<\/td>0.0458<\/td><\/tr>
1-64<\/td>2A<\/td>0.073<\/td>0.0735<\/td>0.0725<\/td>0.0638<\/td>0.0626<\/td>0.0565<\/td><\/tr>
1-64<\/td>3A<\/td>0.073<\/td>0.0733<\/td>0.0727<\/td>0.0642<\/td>0.063<\/td>0.0568<\/td><\/tr>
1-72<\/td>2A<\/td>0.073<\/td>0.0735<\/td>0.0725<\/td>0.0648<\/td>0.0636<\/td>0.0574<\/td><\/tr>
1-72<\/td>3A<\/td>0.073<\/td>0.0733<\/td>0.0727<\/td>0.0652<\/td>0.064<\/td>0.0577<\/td><\/tr>
2-56<\/td>2A<\/td>0.086<\/td>0.0865<\/td>0.0855<\/td>0.0766<\/td>0.0754<\/td>0.069<\/td><\/tr>
2-56<\/td>3A<\/td>0.086<\/td>0.0863<\/td>0.0857<\/td>0.077<\/td>0.0758<\/td>0.0693<\/td><\/tr>
2-64<\/td>2A<\/td>0.086<\/td>0.0865<\/td>0.0855<\/td>0.0776<\/td>0.0764<\/td>0.07<\/td><\/tr>
2-64<\/td>3A<\/td>0.086<\/td>0.0863<\/td>0.0857<\/td>0.078<\/td>0.0768<\/td>0.0703<\/td><\/tr>
3-48<\/td>2A<\/td>0.099<\/td>0.0995<\/td>0.0985<\/td>0.0893<\/td>0.0881<\/td>0.0813<\/td><\/tr>
3-48<\/td>3A<\/td>0.099<\/td>0.0993<\/td>0.0987<\/td>0.0897<\/td>0.0885<\/td>0.0816<\/td><\/tr>
3-56<\/td>2A<\/td>0.099<\/td>0.0995<\/td>0.0985<\/td>0.0903<\/td>0.0891<\/td>0.0823<\/td><\/tr>
3-56<\/td>3A<\/td>0.099<\/td>0.0993<\/td>0.0987<\/td>0.0907<\/td>0.0895<\/td>0.0826<\/td><\/tr>
4-40<\/td>2A<\/td>0.112<\/td>0.1125<\/td>0.1115<\/td>0.1008<\/td>0.0996<\/td>0.0919<\/td><\/tr>
4-40<\/td>3A<\/td>0.112<\/td>0.1123<\/td>0.1117<\/td>0.1012<\/td>0.1<\/td>0.0922<\/td><\/tr>
4-48<\/td>2A<\/td>0.112<\/td>0.1125<\/td>0.1115<\/td>0.1023<\/td>0.1011<\/td>0.0934<\/td><\/tr>
4-48<\/td>3A<\/td>0.112<\/td>0.1123<\/td>0.1117<\/td>0.1027<\/td>0.1015<\/td>0.0937<\/td><\/tr>
5-40<\/td>2A<\/td>0.125<\/td>0.1255<\/td>0.1245<\/td>0.1133<\/td>0.1121<\/td>0.1039<\/td><\/tr>
5-40<\/td>3A<\/td>0.125<\/td>0.1253<\/td>0.1247<\/td>0.1137<\/td>0.1125<\/td>0.1042<\/td><\/tr>
5-44<\/td>2A<\/td>0.125<\/td>0.1255<\/td>0.1245<\/td>0.1143<\/td>0.1131<\/td>0.1049<\/td><\/tr>
5-44<\/td>3A<\/td>0.125<\/td>0.1253<\/td>0.1247<\/td>0.1147<\/td>0.1135<\/td>0.1052<\/td><\/tr>
6-32<\/td>2A<\/td>0.138<\/td>0.1389<\/td>0.1369<\/td>0.1228<\/td>0.1209<\/td>0.107<\/td><\/tr>
6-32<\/td>3A<\/td>0.138<\/td>0.1386<\/td>0.1372<\/td>0.1232<\/td>0.1213<\/td>0.1073<\/td><\/tr>
6-40<\/td>2A<\/td>0.138<\/td>0.1389<\/td>0.1369<\/td>0.125<\/td>0.1231<\/td>0.1111<\/td><\/tr>
6-40<\/td>3A<\/td>0.138<\/td>0.1386<\/td>0.1372<\/td>0.1254<\/td>0.1235<\/td>0.1114<\/td><\/tr>
8-32<\/td>2A<\/td>0.164<\/td>0.1649<\/td>0.1629<\/td>0.1483<\/td>0.1464<\/td>0.1329<\/td><\/tr>
8-32<\/td>3A<\/td>0.164<\/td>0.1646<\/td>0.1632<\/td>0.1487<\/td>0.1468<\/td>0.1332<\/td><\/tr>
8-36<\/td>2A<\/td>0.164<\/td>0.1649<\/td>0.1629<\/td>0.1501<\/td>0.1482<\/td>0.1351<\/td><\/tr>
8-36<\/td>3A<\/td>0.164<\/td>0.1646<\/td>0.1632<\/td>0.1505<\/td>0.1486<\/td>0.1354<\/td><\/tr>
10-24<\/td>2A<\/td>0.19<\/td>0.1909<\/td>0.1889<\/td>0.1683<\/td>0.1664<\/td>0.1497<\/td><\/tr>
10-24<\/td>3A<\/td>0.19<\/td>0.1906<\/td>0.1892<\/td>0.1687<\/td>0.1668<\/td>0.15<\/td><\/tr>
10-32<\/td>2A<\/td>0.19<\/td>0.1909<\/td>0.1889<\/td>0.1749<\/td>0.173<\/td>0.1582<\/td><\/tr>
10-32<\/td>3A<\/td>0.19<\/td>0.1906<\/td>0.1892<\/td>0.1753<\/td>0.1734<\/td>0.1585<\/td><\/tr>
1\/4-20<\/td>2A<\/td>0.25<\/td>0.2511<\/td>0.2489<\/td>0.2263<\/td>0.2238<\/td>0.2019<\/td><\/tr>
1\/4-20<\/td>3A<\/td>0.25<\/td>0.2508<\/td>0.2492<\/td>0.2267<\/td>0.2242<\/td>0.2022<\/td><\/tr>
1\/4-28<\/td>2A<\/td>0.25<\/td>0.2511<\/td>0.2489<\/td>0.2338<\/td>0.2313<\/td>0.2128<\/td><\/tr>
1\/4-28<\/td>3A<\/td>0.25<\/td>0.2508<\/td>0.2492<\/td>0.2342<\/td>0.2317<\/td>0.2131<\/td><\/tr>
5\/16-18<\/td>2A<\/td>0.3125<\/td>0.3138<\/td>0.3112<\/td>0.2832<\/td>0.2805<\/td>0.256<\/td><\/tr>
5\/16-18<\/td>3A<\/td>0.3125<\/td>0.3135<\/td>0.3115<\/td>0.2836<\/td>0.2809<\/td>0.2563<\/td><\/tr>
5\/16-24<\/td>2A<\/td>0.3125<\/td>0.3138<\/td>0.3112<\/td>0.2912<\/td>0.2885<\/td>0.2663<\/td><\/tr>
5\/16-24<\/td>3A<\/td>0.3125<\/td>0.3135<\/td>0.3115<\/td>0.2916<\/td>0.2889<\/td>0.2666<\/td><\/tr>
3\/8-16<\/td>2A<\/td>0.375<\/td>0.3765<\/td>0.3735<\/td>0.3401<\/td>0.3372<\/td>0.3082<\/td><\/tr>
3\/8-16<\/td>3A<\/td>0.375<\/td>0.3762<\/td>0.3738<\/td>0.3405<\/td>0.3376<\/td>0.3085<\/td><\/tr>
3\/8-24<\/td>2A<\/td>0.375<\/td>0.3765<\/td>0.3735<\/td>0.3485<\/td>0.3456<\/td>0.3192<\/td><\/tr>
3\/8-24<\/td>3A<\/td>0.375<\/td>0.3762<\/td>0.3738<\/td>0.3489<\/td>0.346<\/td>0.3195<\/td><\/tr>
7\/16-14<\/td>2A<\/td>0.4375<\/td>0.4392<\/td>0.4358<\/td>0.3963<\/td>0.3931<\/td>0.3595<\/td><\/tr>
7\/16-14<\/td>3A<\/td>0.4375<\/td>0.4384<\/td>0.4366<\/td>0.3968<\/td>0.3937<\/td>0.3598<\/td><\/tr>
7\/16-20<\/td>2A<\/td>0.4375<\/td>0.4392<\/td>0.4358<\/td>0.4108<\/td>0.408<\/td>0.3787<\/td><\/tr>
7\/16-20<\/td>3A<\/td>0.4375<\/td>0.4384<\/td>0.4366<\/td>0.4113<\/td>0.4085<\/td>0.379<\/td><\/tr>
1\/2-13<\/td>2A<\/td>0.5<\/td>0.502<\/td>0.4976<\/td>0.4531<\/td>0.4497<\/td>0.4099<\/td><\/tr>
1\/2-13<\/td>3A<\/td>0.5<\/td>0.5012<\/td>0.4988<\/td>0.4537<\/td>0.4503<\/td>0.4102<\/td><\/tr>
1\/2-20<\/td>2A<\/td>0.5<\/td>0.502<\/td>0.4976<\/td>0.4714<\/td>0.4686<\/td>0.4402<\/td><\/tr>
1\/2-20<\/td>3A<\/td>0.5<\/td>0.5012<\/td>0.4988<\/td>0.4719<\/td>0.4691<\/td>0.4405<\/td><\/tr>
9\/16-12<\/td>2A<\/td>0.5625<\/td>0.5648<\/td>0.5602<\/td>0.5096<\/td>0.5059<\/td>0.4606<\/td><\/tr>
9\/16-12<\/td>3A<\/td>0.5625<\/td>0.5638<\/td>0.5612<\/td>0.5102<\/td>0.5065<\/td>0.4609<\/td><\/tr>
9\/16-18<\/td>2A<\/td>0.5625<\/td>0.5648<\/td>0.5602<\/td>0.5258<\/td>0.523<\/td>0.4971<\/td><\/tr>
9\/16-18<\/td>3A<\/td>0.5625<\/td>0.5638<\/td>0.5612<\/td>0.5263<\/td>0.5235<\/td>0.4974<\/td><\/tr>
5\/8-11<\/td>2A<\/td>0.625<\/td>0.6275<\/td>0.6225<\/td>0.5676<\/td>0.5636<\/td>0.5149<\/td><\/tr>
5\/8-11<\/td>3A<\/td>0.625<\/td>0.6264<\/td>0.6236<\/td>0.5682<\/td>0.5642<\/td>0.5152<\/td><\/tr>
5\/8-18<\/td>2A<\/td>0.625<\/td>0.6275<\/td>0.6225<\/td>0.588<\/td>0.585<\/td>0.556<\/td><\/tr>
5\/8-18<\/td>3A<\/td>0.625<\/td>0.6264<\/td>0.6236<\/td>0.5885<\/td>0.5855<\/td>0.5563<\/td><\/tr>
3\/4-10<\/td>2A<\/td>0.75<\/td>0.7528<\/td>0.7472<\/td>0.6825<\/td>0.678<\/td>0.6151<\/td><\/tr>
3\/4-10<\/td>3A<\/td>0.75<\/td>0.7516<\/td>0.7484<\/td>0.6831<\/td>0.6786<\/td>0.6154<\/td><\/tr>
3\/4-16<\/td>2A<\/td>0.75<\/td>0.7528<\/td>0.7472<\/td>0.7139<\/td>0.7109<\/td>0.6781<\/td><\/tr>
3\/4-16<\/td>3A<\/td>0.75<\/td>0.7516<\/td>0.7484<\/td>0.7144<\/td>0.7114<\/td>0.6784<\/td><\/tr>
7\/8-9<\/td>2A<\/td>0.875<\/td>0.878<\/td>0.872<\/td>0.7977<\/td>0.7927<\/td>0.7185<\/td><\/tr>
7\/8-9<\/td>3A<\/td>0.875<\/td>0.8767<\/td>0.8733<\/td>0.7983<\/td>0.7933<\/td>0.7188<\/td><\/tr>
7\/8-14<\/td>3A<\/td>0.875<\/td>0.8767<\/td>0.8733<\/td>0.8343<\/td>0.8311<\/td>0.7965<\/td><\/tr>
1-8<\/td>2A<\/td>1<\/td>1.003<\/td>0.997<\/td>0.9074<\/td>0.9024<\/td>0.8186<\/td><\/tr>
1-8<\/td>3A<\/td>1<\/td>1.0017<\/td>0.9983<\/td>0.908<\/td>0.903<\/td>0.8189<\/td><\/tr>
1-12<\/td>2A<\/td>1<\/td>1.003<\/td>0.997<\/td>0.949<\/td>0.944<\/td>0.8696<\/td><\/tr>
1-12<\/td>3A<\/td>1<\/td>1.0017<\/td>0.9983<\/td>0.9495<\/td>0.9445<\/td>0.8699<\/td><\/tr>
1-1\/8-7<\/td>2A<\/td>1.125<\/td>1.1285<\/td>1.1215<\/td>1.0474<\/td>1.0416<\/td>0.9486<\/td><\/tr>
1-1\/8-12<\/td>2A<\/td>1.125<\/td>1.1285<\/td>1.1215<\/td>1.0739<\/td>1.0689<\/td>0.9936<\/td><\/tr>
1-3\/8-6<\/td>2A<\/td>1.375<\/td>1.379<\/td>1.371<\/td>1.2899<\/td>1.2833<\/td>1.1816<\/td><\/tr>
1-3\/8-12<\/td>2A<\/td>1.375<\/td>1.379<\/td>1.371<\/td>1.3239<\/td>1.3189<\/td>1.2436<\/td><\/tr>
1-1\/2-6<\/td>2A<\/td>1.5<\/td>1.504<\/td>1.496<\/td>1.4149<\/td>1.4083<\/td>1.3066<\/td><\/tr>
1-1\/2-12<\/td>2A<\/td>1.5<\/td>1.504<\/td>1.496<\/td>1.4489<\/td>1.4439<\/td>1.3686<\/td><\/tr>
1-3\/4-5<\/td>2A<\/td>1.75<\/td>1.7544<\/td>1.7456<\/td>1.656<\/td>1.6484<\/td>1.5352<\/td><\/tr>
2-6<\/td>2A<\/td>2<\/td>2.004<\/td>1.996<\/td>1.9149<\/td>1.9083<\/td>1.8066<\/td><\/tr><\/tbody><\/table>
Table of ANSI External Screw Thread Size & Tolerances Chart<\/figcaption><\/figure>\n\n\n\n

Conclusion<\/strong><\/h2>\n\n\n\n

See MISUMI USA’s full range of screws and fasteners<\/a>, including the following:<\/p>\n\n\n\n

Machine Screws<\/a><\/p>\n\n\n\n

Micro Screws & Precision Screws<\/a><\/p>\n\n\n\n

Hex Socket Button Head Cap Screws<\/a><\/p>\n\n\n\n

If you had further questions on what fastener measurements and dimensions would best fit your needs or projects, please feel free to reach out to our product experts<\/a>. Also, be sure to check out our MechLab Blog<\/a>, and find the answers to any questions you may have had (or not had) about screws and fasteners threads like NPT thread fittings<\/a> and AN fittings and adapters<\/a> .<\/p>\n\n\n\n

<\/p>\n\n\n\n

Disclaimer<\/strong>:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers\u2019 or manufacturers\u2019 deliverables within MISUMI\u2019s network. Buyers are responsible for specifying their part requirements.<\/p>\n","protected":false},"excerpt":{"rendered":"

Author: Scott Bredemann Updated: 03\/24\/2025 | Read Time: 3mins The American National Standards Institute (ANSI) sets guidelines for external screw threads, specifying dimensions and tolerances based on thread class (2A and 3A). These standards help engineers and manufacturers maintain consistency, reduce wear, and improve performance across various industrial and commercial uses. This guide provides a detailed table of ANSI external screw thread […]<\/p>\n","protected":false},"author":70,"featured_media":14567,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/pages\/14565"}],"collection":[{"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/users\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/comments?post=14565"}],"version-history":[{"count":5,"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/pages\/14565\/revisions"}],"predecessor-version":[{"id":14571,"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/pages\/14565\/revisions\/14571"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/media\/14567"}],"wp:attachment":[{"href":"https:\/\/us.misumi-ec.com\/blog\/wp-json\/wp\/v2\/media?parent=14565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}