EXTERNAL ACME THREAD DIMENSIONS TABLE


External ACME thread dimensions are given in the following table per ASME/ANSI B1.5 standard.

Tolerances Of Acme Screw Thread
Allowances, Tolerances, and Clearances for General Purpose Single-start Acme Threads (All Classes)



ACME Thread
Designation
Nominal
Size
Threads
/in.
Tol.
Class
Major
Diameter
Pitch
Diameter
Minor
Diameter
max. min. max. min. max. min.
1/4-16 ACME 0.25 16 2G 0.2500 0.2450 0.2148 0.2043 0.1775 0.1618
3G 0.2158 0.2109 0.1701
4G 0.2168 0.2133 0.1723
5/16-14 ACME 0.3125 14 2G 0.3125 0.3075 0.2728 0.2614 0.2311 0.2140
3G 0.2738 0.2685 0.2231
4G 0.2748 0.2710 0.2254
3/8-12 ACME 0.375 12 2G 0.3750 0.3700 0.3284 0.3161 0.2817 0.2632
3G 0.3296 0.3238 0.2731
4G 0.3309 0.3268 0.2755
7/16-12 ACME 0.4375 12 2G 0.4375 0.4325 0.3909 0.3783 0.3442 0.3253
3G 0.3921 0.3862 0.3354
4G 0.3934 0.3892 0.3379
1/2-10 ACME 0.5 10 2G 0.5000 0.4950 0.4443 0.4306 0.3800 0.3594
3G 0.4458 0.4394 0.3704
4G 0.4472 0.4426 0.3731
5/8-8 ACME 0.625 8 2G 0.6250 0.6188 0.5562 0.5408 0.4800 0.4570
3G 0.5578 0.5506 0.4693
4G 0.5593 0.5542 0.4723
3/4-6 ACME 0.75 6 2G 0.7500 0.7417 0.6598 0.6424 0.5633 0.5371
3G 0.6615 0.6534 0.5511
4G 0.6632 0.6574 0.5546
7/8-6 ACME 0.875 6 2G 0.8750 0.8667 0.7842 0.7663 0.6883 0.6615
3G 0.7861 0.7778 0.6758
4G 0.7880 0.7820 0.6794
1-5 ACME 1 5 2G 1.0000 0.9900 0.8920 0.8726 0.7800 0.7509
3G 0.8940 0.8849 0.7664
4G 0.8960 0.8895 0.7703
1 1/8-5 ACME 1.125 5 2G 1.1250 1.1150 1.0165 0.9967 0.9050 0.8753
3G 1.0186 1.0094 0.8912
4G 1.0208 1.0142 0.8951
1 1/4-5 ACME 1.25 5 2G 1.2500 1.2400 1.1411 1.1210 1.0300 0.9998
3G 1.1433 1.1339 1.0159
4G 1.1455 1.1388 1.0199
1 3/8-4 ACME 1.375 4 2G 1.3750 1.3625 1.2406 1.2186 1.1050 1.0719
3G 1.2430 1.2327 1.0896
4G 1.2453 1.2380 1.0940
1 1/2-4 ACME 1.5 4 2G 1.5000 1.4875 1.3652 1.3429 1.2300 1.1965
3G 1.3677 1.3573 1.2144
4G 1.3701 1.3627 1.2188
1 3/4-4 ACME 1.75 4 2G 1.7500 1.7375 1.6145 1.5916 1.4800 1.4456
3G 1.6171 1.6064 1.4639
4G 1.6198 1.6122 1.4685
2-4 ACME 2 4 2G 2.0000 1.9875 1.8637 1.8402 1.7300 1.6948
3G 1.8665 1.8555 1.7136
4G 1.8693 1.8615 1.7183
2 1/4-3 ACME 2.25 3 2G 2.2500 2.2333 2.0713 2.045 1.8967 1.8572
3G 2.0743 2.062 1.8783
4G 2.0773 2.0685 1.8835
2 1/2-3 ACME 2.5 3 2G 2.5000 2.4833 2.3207 2.2939 2.1467 2.1065
3G 2.3238 2.3113 2.1279
4G 2.3270 2.3181 2.1333
2 3/4-3 ACME 2.75 3 2G 2.7500 2.7333 2.5700 2.5427 2.3967 2.3558
3G 2.5734 2.5607 2.3776
4G 2.5767 2.5676 2.3831
3-2 ACME 3 2 2G 3.0000 2.9750 2.7360 2.7044 2.4800 2.4326
3G 2.7395 2.7248 2.4579
4G 2.7430 2.7325 2.4642
3 1/2-2 ACME 3.5 2 2G 3.5000 3.4750 3.2350 3.2026 2.9800 2.9313
3G 3.2388 3.2237 2.9573
4G 3.2425 3.2317 2.9638
4-2 ACME 4 2 2G 4.0000 3.9750 3.7340 3.7008 3.4800 3.4302
3G 3.7380 3.7225 3.4568
4G 3.7420 3.7309 3.4634
4 1/2-2 ACME 4.5 2 2G 4.5000 4.4750 4.2330 4.1991 3.9800 3.9291
3G 4.2373 4.2215 3.9562
4G 4.2415 4.2302 3.9630
5-2 ACME 5 2 2G 5.0000 4.9750 4.7319 4.6973 4.4800 4.4281
3G 4.7364 4.7202 4.4558
4G 4.7409 4.7294 4.4627

Definitions:


Design Profile: The shapes of the external and internal threads in which the limits of dimensions are applied. The thread form of General Purpose Acme Thread is given in the following figure.

General Purpose Acme Thread Form
General Purpose Acme Thread Form

Major Diameter: The maximum diameter of a thread which is diameter of the crest of a male thread or root of a female thread.

Minor Diameter: The minimum diameter of a thread which is diameter of the root of a male thread or crest of a female thread.

Thread class: A classification system to classify the threads for interchangeability and manufacturability.

Threads per inch: Number of full thread per an inch length.


Supplements:


Link Usage
Acme Thread Dimensions Calculator Calculator form of the ACME thread dimensions chart.
Internal ACME Thread Dimensions Chart Tabulated form of the ACME thread dimensions calculator.

Reference:

  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.
  • ASME B1.5-1997, Acme Screw Threads