UNC/UNRC - Coarse 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)

#1* 0.073 64 0.0629 0.0544 0.0561 0.00218 0.00263
#2 0.086 56 0.0744 0.0648 0.0667 0.0031 0.0037
#3* 0.099 48 0.0855 0.0741 0.0764 0.00406 0.00487
#4 0.112 40 0.0958 0.0822 0.0849 0.00496 0.00604
#5 0.125 40 0.1088 0.0952 0.0979 0.00672 0.00796
#6 0.138 32 0.1177 0.1008 0.1042 0.00745 0.00909
#8 0.164 32 0.1437 0.1268 0.1302 0.01196 0.014
#10 0.19 24 0.1629 0.1404 0.1449 0.0145 0.0175
#12* 0.216 24 0.1889 0.1664 0.1709 0.0206 0.0242
1/4 0.25 20 0.2175 0.1905 0.1959 0.0269 0.0318
5/16 0.3125 18 0.2764 0.2464 0.2524 0.0454 0.0524
3/8 0.375 16 0.3344 0.3005 0.3073 0.0678 0.0775
7/16 0.4375 14 0.3911 0.3525 0.3602 0.0933 0.1063
1/2 0.5 13 0.45 0.4084 0.4167 0.1257 0.1419
9/16 0.5625 12 0.5084 0.4633 0.4723 0.162 0.182
5/8 0.625 11 0.566 0.5168 0.5266 0.202 0.226
3/4 0.75 10 0.685 0.6309 0.6417 0.302 0.334
7/8 0.875 9 0.8028 0.7427 0.7547 0.419 0.462
1 1 8 0.9188 0.8512 0.8647 0.551 0.606
1 1/8 1.125 7 1.0322 0.9549 0.9704 0.693 0.763
1 1/4 1.25 7 1.1572 1.0799 1.0954 0.89 0.969
1 3/8 1.375 6 1.2667 1.1766 1.1946 1.054 1.155
1 1/2 1.5 6 1.3917 1.3016 1.3196 1.294 1.405
1 3/4 1.75 5 1.6201 1.5119 1.5335 1.74 1.9
2 2 4.5 1.8557 1.7353 1.7594 2.3 2.5
2 1/4 2.25 4.5 2.1057 1.9853 2.0094 3.02 3.25
2 1/2 2.5 4 2.3376 2.2023 2.2294 3.72 4
2 3/4 2.75 4 2.5876 2.4523 2.4794 4.62 4.93
3 3 4 2.8376 2.7023 2.7294 5.62 5.97
3 1/4 3.25 4 3.0876 2.9523 2.9794 6.72 7.1
3 1/2 3.5 4 3.3376 3.2023 3.2294 7.92 8.33
3 3/4 3.75 4 3.5876 3.4523 3.4794 9.21 9.66
4 4 4 3.8376 3.7023 3.7294 10.61 11.08
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.