Internal ACME Thread General Purpose Size Chart

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ANSI Hardware Engineering Data
External ACME Thread General Purpose Size Table Chart

The following table defines recommended industry standard sizes for Internal ACME General Purpose Threads per American National Standard ASME/ANSI B1.5. All dimensional data is given in inches.

ACME Internal Thread

Designation	Size Decimal	TPI	Tol. Class	Minor Dia.		Major Dia.
Designation	Size Decimal	TPI	Tol. Class	Min.	Max.	Min.	Max.
1/4-16 ACME	0.25	16	2G	0.1875	0.1925	0.2600	0.2700
1/4-16 ACME	0.25	16	3G	0.1875	0.1925	0.2600	0.2700
1/4-16 ACME	0.25	16	4G	0.1875	0.1925	0.2600	0.2700
1/4-16 ACME	0.25	16	5G	0.1875	0.1925	0.2600	0.2700
5/16-14 ACME	0.3125	14	2G	0.2411	0.2461	0.3225	0.3325
5/16-14 ACME	0.3125	14	3G	0.2411	0.2461	0.3225	0.3325
5/16-14 ACME	0.3125	14	4G	0.2411	0.2461	0.3225	0.3325
5/16-14 ACME	0.3125	14	5G	0.2411	0.2461	0.3225	0.3325
3/8-12 ACME	0.375	12	2G	0.2917	0.2967	0.3850	0.3950
3/8-12 ACME	0.375	12	3G	0.2917	0.2967	0.3850	0.3950
3/8-12 ACME	0.375	12	4G	0.2917	0.2967	0.3850	0.3950
3/8-12 ACME	0.375	12	5G	0.2917	0.2967	0.3850	0.3950
7/16-12 ACME	0.4375	12	2G	0.3542	0.3592	0.4475	0.4575
7/16-12 ACME	0.4375	12	3G	0.3542	0.3592	0.4475	0.4575
7/16-12 ACME	0.4375	12	4G	0.3542	0.3592	0.4475	0.4575
7/16-12 ACME	0.4375	12	5G	0.3542	0.3592	0.4475	0.4575
1/2-10 ACME	0.5	10	2G	0.4000	0.4050	0.52	0.5400
1/2-10 ACME	0.5	10	3G	0.4000	0.4050	0.52	0.5400
1/2-10 ACME	0.5	10	4G	0.4000	0.4050	0.52	0.5400
1/2-10 ACME	0.5	10	5G	0.4000	0.4050	0.52	0.5400
5/8-8 ACME	0.625	8	2G	0.5000	0.5062	0.645	0.6650
5/8-8 ACME	0.625	8	3G	0.5000	0.5062	0.645	0.6650
5/8-8 ACME	0.625	8	4G	0.5000	0.5062	0.645	0.6650
5/8-8 ACME	0.625	8	5G	0.5000	0.5062	0.645	0.6650
3/4-6 ACME	0.75	6	2G	0.5833	0.5916	0.77	0.7900
3/4-6 ACME	0.75	6	3G	0.5833	0.5916	0.77	0.7900
3/4-6 ACME	0.75	6	4G	0.5833	0.5916	0.77	0.7900
3/4-6 ACME	0.75	6	5G	0.5833	0.5916	0.77	0.7900
7/8-6 ACME	0.875	6	2G	0.7083	0.7166	0.895	0.9150
7/8-6 ACME	0.875	6	3G	0.7083	0.7166	0.895	0.9150
7/8-6 ACME	0.875	6	4G	0.7083	0.7166	0.895	0.9150
7/8-6 ACME	0.875	6	5G	0.7083	0.7166	0.895	0.9150
1-5 ACME	1	5	2G	0.8000	0.8100	1.02	1.0400
1-5 ACME	1	5	3G	0.8000	0.8100	1.02	1.0400
1-5 ACME	1	5	4G	0.8000	0.8100	1.02	1.0400
1-5 ACME	1	5	5G	0.8000	0.8100	1.02	1.0400
1 1/8-5 ACME	1.125	5	2G	0.9250	0.9350	1.145	1.165
1 1/8-5 ACME	1.125	5	3G	0.9250	0.9350	1.145	1.165
1 1/8-5 ACME	1.125	5	4G	0.9250	0.9350	1.145	1.165
1 1/8-5 ACME	1.125	5	5G	0.9250	0.9350	1.145	1.165
1 1/4-5 ACME	1.25	5	2G	1.0500	1.0600	1.27	1.29
1 1/4-5 ACME	1.25	5	3G	1.0500	1.0600	1.27	1.29
1 1/4-5 ACME	1.25	5	4G	1.0500	1.0600	1.27	1.29
1 1/4-5 ACME	1.25	4	5G	1.0500	1.0600	1.27	1.29
1 3/8-4 ACME	1.375	4	2G	1.1250	1.1375	1.395	1.415
1 3/8-4 ACME	1.375	4	3G	1.1250	1.1375	1.395	1.415
1 3/8-4 ACME	1.375	4	4G	1.1250	1.1375	1.395	1.415
1 3/8-4 ACME	1.375	4	5G	1.1250	1.1375	1.395	1.415
1 1/2-4 ACME	1.5	4	2G	1.2500	1.2625	1.52	1.54
1 1/2-4 ACME	1.5	4	3G	1.2500	1.2625	1.52	1.54
1 1/2-4 ACME	1.5	4	4G	1.2500	1.2625	1.52	1.54
1 1/2-4 ACME	1.5	4	5G	1.2500	1.2625	1.52	1.54
1 3/4-4 ACME	1.75	4	2G	1.5000	1.5125	1.77	1.79
1 3/4-4 ACME	1.75	4	3G	1.5000	1.5125	1.77	1.79
1 3/4-4 ACME	1.75	4	4G	1.5000	1.5125	1.77	1.79
1 3/4-4 ACME	1.75	4	5G	1.5000	1.5125	1.77	1.79
2-4 ACME	2	4	2G	1.7500	1.7625	2.02	2.04
2-4 ACME	2	4	3G	1.7500	1.7625	2.02	2.04
2-4 ACME	2	4	4G	1.7500	1.7625	2.02	2.04
2-4 ACME	2	4	5G	1.7500	1.7625	2.02	2.04
2 1/4-3 ACME	2.25	3	2G	1.9167	1.9334	2.27	2.29
2 1/4-3 ACME	2.25	3	3G	1.9167	1.9334	2.27	2.29
2 1/4-3 ACME	2.25	3	4G	1.9167	1.9334	2.27	2.29
2 1/4-3 ACME	2.25	3	5G	1.9167	1.9334	2.27	2.29
2 1/2-3 ACME	2.5	3	2G	2.1667	2.1834	2.52	2.54
2 1/2-3 ACME	2.5	3	3G	2.1667	2.1834	2.52	2.54
2 1/2-3 ACME	2.5	3	4G	2.1667	2.1834	2.52	2.54
2 1/2-3 ACME	2.5	3	5G	2.1667	2.1834	2.52	2.54
2 3/4-3 ACME	2.75	3	2G	2.4169	2.4334	2.77	2.79
2 3/4-3 ACME	2.75	3	3G	2.4169	2.4334	2.77	2.79
2 3/4-3 ACME	2.75	3	4G	2.4169	2.4334	2.77	2.79
2 3/4-3 ACME	2.75	3	5G	2.4169	2.4334	2.77	2.79
3-2 ACME	3	2	2G	2.5000	2.5250	3.02	3.04
3-2 ACME	3	2	3G	2.5000	2.5250	3.02	3.04
3-2 ACME	3	2	4G	2.5000	2.5250	3.02	3.04
3-2 ACME	3	2	5G	2.5000	2.5250	3.02	3.04
3 1/2-2 ACME	3.5	2	2G	3.0000	3.0250	3.52	3.54
3 1/2-2 ACME	3.5	2	3G	3.0000	3.0250	3.52	3.54
3 1/2-2 ACME	3.5	2	4G	3.0000	3.0250	3.52	3.54
3 1/2-2 ACME	3.5	2	5G	3.0000	3.0250	3.52	3.54
4-2 ACME	4	2	2G	3.5000	3.5250	4.02	4.04
4-2 ACME	4	2	3G	3.5000	3.5250	4.02	4.04
4-2 ACME	4	2	4G	3.5000	3.5250	4.02	4.04
4-2 ACME	4	2	5G	3.5000	3.5250	4.02	4.04
4 1/2-2 ACME	4.5	2	2G	4.0000	4.0250	4.52	4.54
4 1/2-2 ACME	4.5	2	3G	4.0000	4.0250	4.52	4.54
4 1/2-2 ACME	4.5	2	4G	4.0000	4.0250	4.52	4.54
4 1/2-2 ACME	4.5	2	5G	4.0000	4.0250	4.52	4.54
5-2 ACME	5	2	2G	4.5000	4.5250	5.02	5.04
5-2 ACME	5	2	3G	4.5000	4.5250	5.02	5.04
5-2 ACME	5	2	4G	4.5000	4.5250	5.02	5.04
5-2 ACME	5	2	5G	4.5000	4.5250	5.02	5.04

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Designation	TPI	Tol. Class	Pitch Dia.		Tap Drill
Designation	TPI	Tol. Class	Min.	Max.	Tap Drill
1/4-16 ACME	16	2G	0.2188	0.2293	0.1875
1/4-16 ACME	16	3G	0.2188	0.2237	0.1875
1/4-16 ACME	16	4G	0.2188	0.2223	0.1875
1/4-16 ACME	16	5G	0.2188	0.2216	0.1875
5/16-14 ACME	14	2G	0.2768	0.2882	0.2411
5/16-14 ACME	14	3G	0.2768	0.2821	0.2411
5/16-14 ACME	14	4G	0.2768	0.2806	0.2411
5/16-14 ACME	14	5G	0.2768	0.2798	0.2411
3/8-12 ACME	12	2G	0.3333	0.3456	0.2917
3/8-12 ACME	12	3G	0.3333	0.3391	0.2917
3/8-12 ACME	12	4G	0.3333	0.3374	0.2917
3/8-12 ACME	12	5G	0.3333	0.3366	0.2917
7/16-12 ACME	12	2G	0.3958	0.4084	0.3542
7/16-12 ACME	12	3G	0.3958	0.4017	0.3542
7/16-12 ACME	12	4G	0.3958	0.4000	0.3542
7/16-12 ACME	12	5G	0.3958	0.3992	0.3542
1/2-10 ACME	10	2G	0.4500	0.4637	0.4000
1/2-10 ACME	10	3G	0.4500	0.4564	0.4000
1/2-10 ACME	10	4G	0.4500	0.4546	0.4000
1/2-10 ACME	10	5G	0.4500	0.4537	0.4000
5/8-8 ACME	8	2G	0.5625	0.5779	0.5000
5/8-8 ACME	8

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