UNF Threads

 

The UNF thread is the "American fine thread" and is used in the USA, comparable to the metric fine thread in Europe. The fine thread achieves a higher holding force. In the UNF thread table below you will find technical data as well as tightening torque for UNF threads.

 

 Example:

1/4 inch - 28 x 1/2 inch hex bolt

1/4 = Thread outer diameter 6.35 mm

28 = number of threads to inch (25.4 mm) length

1/2 = length of screw from head 12,70 mm

 

UNF Threads Chart

 

UNF (Fine Thread) Flank Angle 60°

 

Technical Data:

Tightening

Torque in (Nm)

Inch

Gear number

per Inch (Zoll)

Thread Ø

outside in mm

Grade 1

(equivalent to 4.6)

Grade 2

(equivalent to 5.6)

Grade 5

(equivalent to 8.8)

Grade 8

(equivalent to 10.9)

Nr. 000 (UNF 000-120) 120 0,864 mm        
Nr. 00 (UNF 00-96) 96 1,194 mm        
Nr. 0 (UNF 0-80) 80 1,524 mm        
Nr. 1 (UNF 1-72) 72 1,854 mm        
Nr. 2 (UNF 2-64) 64 2,184 mm        
Nr. 3 (UNF 3-56) 56 2,515 mm        
Nr. 4 (UNF 4-48) 48 2,845 mm        
Nr. 5 (UNF 5-44) 44 3,175 mm        
Nr. 6 (UNF 6-40) 40 3,505 mm        
Nr. 8 (UNF 8-36) 36 4,166 mm        
Nr. 10 (UNF 10-32)

32

4,763 mm        
Nr. 12 (UNF 12-28) 28 5,486 mm        
1/64"   0,397 mm        
1/32"   0,794 mm        
1/16"   1,587 mm        
1/8"   3,175 mm        
1/4" 28 6,350 mm 4 7 11 16
5/16" 24 7,938 mm 9 14 23 33
3/8" 24 9,525 mm 16 26 41 58
7/16" 20 11,112 mm 26 41 65 92
1/2" 20 12,700 mm 39 62 100 141
9/16" 18 14,288 mm 56 88 142 201
5/8" 18 15,875 mm 79 123 199 282
11/16"   17,462 mm        
3/4" 16 19,050 mm 137 216 348 494
13/16"   20,638 mm        
7/8" 14 22,225 mm 217 290 556 786
15/16"   23,812 mm        
1" 12 25,400 mm 332 442 848 1199
1 1/8" 12 28,575 mm 471 626 1201 1696
1 1/4" 12 31,750 mm 655 873 1673 2365
1 3/8" 12 34,925 mm 883 1177 2255 3187
1 1/2" 12 38,100 mm 1158 1543 2959 4181
1 9/16"   39,688 mm        
1 5/8"   41,275 mm 1485 1980 3794 5362
1 3/4"   44,450 mm 1869 2491 4776 6747
2"   50,800 mm 2823 3764 7215 10194
2 1/4"   57,150 mm 4057 5410 10369 14653
2 1/2"   63,500 mm 5608 7477 14332 20251

* All information without guarantee.

Tip !

Here, tools to measure a thread.