UNEF/UNREF - Extra Fine Thread (in)

Written by Matt Milbury. Posted in Thread Datasheets

Bolt

Size

Major

Diameter


(in)

Threads

per Inch


(tpi)

Pitch

Diameter


(in)

Minor

Diameter

External

(in) a)

Minor

Diameter

Internal

(in) b)

Minor

Diameter

Area

(sq in)

Tensile

Stress

Area

(sq in)

#12* (0.216) 0.2160 32 0.1957 0.1788 0.1822 0.0242 0.0270
1/4 0.2500 32 0.2297 0.2128 0.2162 0.0344 0.0379
5/16 0.3125 32 0.2922 0.2753 0.2787 0.0581 0.0625
3/8 0.3750 32 0.3547 0.3378 0.3412 0.0878 0.0932
7/16 0.4375 28 0.4143 0.3949 0.3988 0.1201 0.1274
1/2 0.5000 28 0.4768 0.4574 0.4613 0.1620 0.1700
9/16 0.5625 24 0.5354 0.5129 0.5174 0.2030 0.2140
5/8 0.6250 24 0.5979 0.5754 0.5799 0.2560 0.2680
11/16* 0.6875 24 0.6604 0.6379 0.6424 0.3150 0.3290
3/4 0.7500 20 0.7175 0.6905 0.6959 0.3690 0.3860
13/16* 0.8125 20 0.7800 0.7530 0.7584 0.4390 0.4580
7/8 0.8750 20 0.8425 0.8155 0.8209 0.5150 0.5360
15/16* 0.9375 20 0.9050 0.8780 0.8834 0.5980 0.6200
1 1.0000 20 0.9675 0.9405 0.9459 0.6870 0.7110
1 1/16* 1.0625 18 1.0264 0.9964 1.0024 0.7700 0.7990
1 1/8 1.1250 18 1.0889 1.0589 1.0649 0.8710 0.9010
1 3/16* 1.1875 18 1.1514 1.1214 1.1274 0.9770 1.0090
1 1/4 1.2500 18 1.2139 1.1839 1.1899 1.0900 1.1230
1 5/16* 1.3125 18 1.2764 1.2464 1.2524 1.2080 1.2440
1 3/8 1.3750 18 1.3389 1.3089 1.3149 1.3330 1.3700
1 7/16* 1.4375 18 1.4014 1.3714 1.3774 1.4640 1.5030
1 1/2 1.5000 18 1.4639 1.4339 1.4399 1.6000 1.6400
1 9/16* 1.5625 18 1.5264 1.4964 1.5024 1.7400 1.7900
1 5/8 1.6250 18 1.5889 1.5589 1.5649 1.8900 1.9400
1 11/16* 1.6875 18 1.6514 1.6214 1.6274 2.0500 2.1000
Bolt

Size

Major

Diameter


(in)

Threads

per Inch


(tpi)

Pitch

Diameter


(in)

Minor

Diameter

External

(in) a)

Minor

Diameter

Internal

(in) b)

Minor

Diameter

Area

(sq in)

Tensile

Stress

Area

(sq in)

* Secondary Sizea) Form for UNR threadb) Basic Minor Diameter

Notes:

  • a) For Class 2A threads with coating (plating) the max. is increased by the allowance, to the basic size. This is the same value as Class 3A.
  • b) For uncoated hot-rolled, but not standard fasteners with cold rolled threads.
  • c) UN series external thread, Max. Diameter, allows for Class 1A and 2A and basic for Class 3A.