螺紋代號

基本尺寸

英寸

大徑mm
d=D

螺距mm

p

每英寸牙數
tpi

中徑mm
d2=D2

小徑
外螺紋
d3

牙型高度
H1

圓弧尺寸
r

底孔尺寸
mm

R 1/16

1/16"

7.723

0.907

28

7.142

6.561

0.581

0.125

6.4

R 1/8

1/8"

9.728

0.907

28

9.147

8.566

0.581

0.125

8.4

R 1/4

1/4"

13.157

1.337

19

12.301

11.445

0.856

0.184

11.2

R 3/8

3/8"

16.662

1.337

19

15.806

14.950

0.856

0.184

14.75

R 1/2

1/2"

20.955

1.814

14

19.793

18.631

1.162

0.249

18.25

R 3/4

3/4"

26.441

1.814

14

25.279

24.117

1.162

0.249

23.75

R 1

1"

33.249

2.309

11

31.77

30.291

1.479

0.317

30

R 1 1/4

1 1/4"

41.910

2.309

11

40.431

38.952

1.479

0.317

38.5

R 1 1/2

1 1/2"

47.803

2.309

11

46.324

44.845

1.479

0.317

44.5

R 2

2"

59.614

2.309

11

58.135

56.656

1.479

0.317

56

R 2 1/2

2 1/2"

75.184

2.309

11

73.705

72.226

1.479

0.317

71

R 3

3"

87.884

2.309

11

86.405

84.926

1.479

0.317

85.5

R 4

4"

113.030

2.309

11

111.551

110.072

1.479

0.317

110.5

R 5

5"

138.430

2.309

11

136.951

135.472

1.479

0.317

136

R 6

6"

163.830

2.309

11

162.351

160.872

1.479

0.317

161.5

美制粗螺紋

美制細螺紋

規格 （UNC)

標準徑

2級牙鉆孔徑

規格 （UNF)

標準徑

2級牙鉆孔徑

最大

最小

最大

最小

NO.1-64(1.854)

1.55

1.582

1.425

NO.0-80(1.524)

1.25

1.305

1.182

NO.2-56(2.184)

1.80

1.871

1.695

NO.1-72(1.854)

1.55

1.612

1.474

NO.3-48(2.515)

2.10

2.146

1.941

NO.2-64(2.184)

1.85

1.912

1.756

NO.4-40(2.845)

2.30

2.385

2.157

NO.3-56(2.515)

2.10

2.197

2.025

NO.5-40(3.175)

2.60

2.697

2.487

NO.4-48(2.845)

2.40

2.458

2.271

NO.6-32(3.505)

2.80

2.895

2.642

NO.5-44(3.175)

2.70

2.740

2.551

NO.8-32(4.166)

3.40

3.530

3.302

NO.6-40(3.505)

2.90

3.022

2.820

NO.10-24(4.826)

3.90

3.962

3.683

NO.8-36(4.166)

3.50

3.606

3.404

NO.12-24(5.486)

4.50

4.597

4.344

NO.10-32(4.826)

4.10

4.165

3.963

1/4 -20

5.10

5.257

4.979

NO.12-28(5.846)

4.60

4.724

4.496

5/16 -18

6.60

6.731

6.401

1/4-28

5.50

5.588

5.360

3/8 -16

8.00

8.153

7.798

5/16-24

6.90

7.035

6.782

7/16 -14

9.40

9.550

9.144

3/8-24

8.50

8.636

8.382

1/2 -13

10.80

11.023

10.592

7/16-20

9.90

10.033

9.729

9/16 -12

12.20

12.446

11.989

1/2-20

11.50

11.607

11.329

5/8 -11

13.60

12.868

13.386

9/16-18

12.90

13.081

12.751

3/4 -10

16.50

18.840

16.307

5/8-18

14.50

14.681

14.351

7/8 -9

19.50

19.761

19.177

3/4-16

17.50

17.678

17.323

1-8

22.20

22.606

21.971

7/8-14

20.50

20.675

20.270

1-1/8-7

25.00

25.349

24.638

1-12

23.20

23.571

23.114

1-1/4-7

28.20

28.524

27.813

1-1/8-12

26.50

26.746

26.289

1-3/8-6

30.80

31.115

30.353

1-1/4-12

29.50

29.921

29.464

1-1/2-6

34.00

34.290

33.528

1-3/8-12

32.80

33.096

32.639

1-3/4-5

39.50

39.827

38.964

1-1/2-12

36.0

36.271

35.814

2-4-1/2

45.20

45.593

44.679

美制迫牙絲攻鉆孔徑

美制特細螺紋

規格

精度等級

規格 （UNEF)

標準徑

2級牙鉆孔徑

G4-G6

G7-G8

G9

最大

最小

NO.2-56UNC

1.94

-

-

NO.12-32

4.70

4.826

4.623

NO.3-48

2.23

-

-

1/4--32

5.60

5.690

5.486

NO.4-40

2.50

-

-

5/16-32

7.10

7.264

7.087

NO.5-40

2.83

-

-

3/8-32

8.70

8.865

8.661

NO.6-32

3.07

-

-

7/16-28

10.20

10.338

10.135

NO.8-32

3.73

3.77

-

1/2-28

11.80

11.938

11.709

NO.10-24

4.24

4.30

-

9/16-24

13.20

13.386

13.132

NO.12-24

4.90

4.96

-

5/8-24

14.80

14.986

14.732

1/4-20

-

5.72

-

3/4-20

17.80

17.958

17.678

5/16-18

-

7.24

-

7/8-20

21.00

21.133

20.853

3/8-16

-

8.74

8.81

1-20

24.00

24.308

24.028

7/16-14

-

10.20

10.30

美制管螺紋

1/2-13

11.27

11.82

NO.2-64UNF

1.97

-

-

規格

鉆孔徑

NO.3-56

2.27

-

-

NPT

NPS

NO.4-48

2.56

-

-

使用絞刀時

不用絞刀時

NO.5-44

2.86

-

-

1/16-27

6.10

6.25

6.35

NO.6-40

3.16

-

-

1/8-27

8.33

8.43

8.74

NO.8-36

3.78

-

-

1/4-18

10.72

11.13

11.13

NO.10-32

4.39

4.43

-

3/8-18

14.27

14.27

14.68

NO.12-28

4.99

5.04

-

1/2-14

17.48

17.86

18.26

1/4-28

5.85

5.90

-

3/4-14

22.63

23.01

23.42

5/16-24

7.36

7.41

-

1-11-1/2

28.58

28.98

29.36

3/8-24

-

9.00

-

1-1/4-11-1/2

37.31

37.69

38.10

7/16-20

-

10.48

10.54

1-1/2-11-1/2

43.66

44.04

44.45

1/2-20

-

12.07

12.13

2-11-1/2

55.58

55.96

56.36

英制電器螺紋

規格

鉆孔徑

2BA

4.0-4.2

3BA

4BA

3.0-3.2

5BA

2.7-2.8

6BA

2.4-2.5