UNF/UNRF - 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)

#0 0.06 80 0.0519 0.0451 0.0465 0.00151 0.0018
#1$ 0.073 72 0.064 0.0565 0.058 0.00237 0.00278
#2 0.086 64 0.0759 0.0674 0.0691 0.00339 0.00394
#3* 0.099 56 0.0874 0.0778 0.0797 0.00451 0.00523
#4 0.112 48 0.0985 0.0871 0.0894 0.00566 0.00661
#5 0.125 44 0.1102 0.0979 0.1004 0.00716 0.0083
#6 0.138 40 0.1218 0.1082 0.1109 0.00874 0.01015
#8 0.164 36 0.146 0.1309 0.1339 0.01285 0.01474
#10 0.19 32 0.1697 0.1528 0.1562 0.0175 0.02
#12* 0.216 28 0.1928 0.1734 0.1773 0.0226 0.0258
1/4 0.25 28 0.2268 0.2074 0.2113 0.0326 0.0364
5/16 0.3125 24 0.2854 0.2629 0.2674 0.0524 0.058
3/8 0.375 24 0.3479 0.3254 0.3299 0.0809 0.0878
7/16 0.4375 20 0.405 0.378 0.3834 0.109 0.1187
1/2 0.5 20 0.4675 0.4405 0.4459 0.1486 0.1599
9/16 0.5625 18 0.5264 0.4964 0.5024 0.189 0.203
5/8 0.625 18 0.5889 0.5589 0.5649 0.24 0.256
3/4 0.75 16 0.7094 0.6763 0.6823 0.351 0.373
7/8 0.875 14 0.8286 0.79 0.7977 0.48 0.509
1 1 12 0.9459 0.9001 0.9098 0.625 0.663
1-1/8 1.125 12 1.0709 1.0258 1.0348 0.812 0.856
1 1/4 1.25 12 1.1959 1.1508 1.1598 1.024 1.073
1 3/8 1.375 12 1.3209 1.2758 1.2848 1.26 1.315
1 1/2 1.5 12 1.4459 1.4008 1.4098 1.521 1.581
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.

Bo