EXTERNAL ACME THREAD DIMENSIONS TABLE


External ACME thread dimensions chart per ASME/ANSI B1.5 standard.

ACME Thread Chart

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


External ACME thread dimensions table
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
ACME Thread
Designation
Nominal
Size
Threads
/in.
Tol.
Class
Major
Diameter
Pitch
Diameter
Minor
Diameter
max. min. max. min. max. min.
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
ACME Thread
Designation
Nominal
Size
Threads
/in.
Tol.
Class
Major
Diameter
Pitch
Diameter
Minor
Diameter
max. min. max. min. max. min.
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
ACME Thread
Designation
Nominal
Size
Threads
/in.
Tol.
Class
Major
Diameter
Pitch
Diameter
Minor
Diameter
max. min. max. min. max. min.
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
ACME Thread
Designation
Nominal
Size
Threads
/in.
Tol.
Class
Major
Diameter
Pitch
Diameter
Minor
Diameter
max. min. max. min. max. min.
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:

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:

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