UNF Thread ANSI B1.1

UNF - Unified National Fine Thread. Similar to UNC. UNC and UNF threads are the choices for the customary Unified screws and nuts.

Nominal
Diameter

Major
Diameter
Inch

Major
Diameter
mm

Tapping Drill
Size
mm

TPI

Pitch
mm

0 - 80 UNF

0.060

1.524

1.25

80

0.317

1 - 72 UNF

0.073

1.854

1.55

72

0.353

2 - 64 UNF

0.068

2.184

1.90

64

0.397

3 - 56 UNF

0.099

2.515

2.15

56

0.453

4 - 48 UNF

0.112

2.845

2.40

48

0.529

5 - 44 UNF

0.125

3.175

2.70

44

0.577

6 - 40 UNF

0.138

3.505

2.95

40

0.635

8 - 36 UNF

0.164

4.166

3.50

36

0.705

10 - 32 UNF

0.190

4.826

4.10

32

0.794

12 - 28 UNF

0.216

5.486

4.70

28

0.907

1/4" - 28 UNF

0.250

6.350

5.50

28

0.907

5/16" - 24 UNF

0.313

7.938

6.90

24

1.058

3/8" - 24 UNF

0.375

9.525

8.50

24

1.058

7/16" - 20 UNF

0.438

11.112

9.90

20

1.270

1/2" - 20 UNF

0.500

12.700

11.50

20

1.270

9/16" - 18 UNF

0.563

14.288

12.90

18

1.411

5/8" - 18 UNF

0.625

15.875

14.50

18

1.411

3/4" - 16 UNF

0.750

19.050

17.50

16

1.587

7/8" - 14 UNF

0.875

22.225

20.40

14

1.814

1" - 12 UNF

1.000

25.400

23.25

12

2.117

1 1/8" - 12 UNF

1.125

28.575

26.50

12

2.117

1 1/4" - 12 UNF

1.250

31.750

29.50

12

2.117

1 3/8" - 12 UNF

1.375

34.925

32.75

12

2.117

1 1/2" - 12 UNF

1.500

38.100

36.00

12

2.117