FASTENERS 1 Inch Bolts & Screws
REFERENCE CHART — DETERMINING THREAD LENGTHS INCH
LENGTH STANDARDS FOR FULL OR PARTIAL THREADS
There is a formula for calculating minimum length of threads on any given hex head cap screw. It is as follows: Minimum thread length equals twice the basic thread diameter plus .250 inches for screw lengths up to and including six inches and twice the basic thread diameter plus .500 inches for lengths over six inches. The chart to the left is also a useful tool for determining at which lengths a given diameter bolt changes from fully threaded to partially threaded, according to industry specifications.
Capscrew Diameter Fully Threaded Max. Length* Capscrew Diameter Fully Threaded Max. Length*
1/4” 5/16” 3/8” 7/16” 1/2” 9/16” 1-1/4 1-3/8 1-1/2 1-3/4 1-7/8 2-1/8
5/8”
3/4” 7/8”
1”
7/8”
1”
1
2-1/4 2-5/8 2-7/8 3-1/4 3-3/4 4
*These lengths and longer = partially threaded
REFERENCE CHART — INCH SIZE TO DECIMAL, THREAD PITCH SIZE TO DECIMAL CONVERSION Nominal Size in No. Basic Major Dia. in. D STANDARD THREAD PITCH Bolt Size No. or Inches Nominal Size in No.
Threads Per Inch (TPI) Coarse Thread UNC Fine Thread UNF
Threads Per Inch (TPI) Coarse Thread UNC Fine Thread UNF
Basic Major Dia. in. D
Bolt Size No. or Inches
0 1 2 3 4 5 6 8
0.0600 0.0730 0.0860 0.0990 0.1120 0.1250 0.1380 0.1640 0.1900 0.2160 0.2500 0.3125 0.3750 0.4375 0.5000
80 72 64 56 48 44 40 36 32 28 28 24 24 20 20 18 18 16
9 8 7 7 6 6 5 4 4 4 4 4 4 4
14 12 12 12 12 12
0 1 2 3 4 5 6 8
7/8
9/16 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2
0.5625 0.6250 0.7500 0.8750 1.0000 1.1250 1.2500 1.3750 1.5000
64 56 48 40 40 32 32 24 24 20 18 16 14 13 12 11 10
1
1-1/8 1-1/4 1-3/8 1-1/2 1-3/4 2-1/4 2-1/2 2 2-3/4 3-1/4 3-1/2 3 3-3/4
10 12
4-1/2 4-1/2
10 12 1/4
1/4 5/16 3/8 7/16 1/2
5/16 3/8 7/16 1/2 9/16 5/8 3/4
4
BIT SELECTION CHARTS
PHILLIPS BITS
SHEET METAL SCREW SIZE FLAT, OVAL, ROUND
WOOD SCREW SIZE
MACHINE SCREW SIZE
BIT SIZE
FLAT, OVAL ROUND TRUSS
FLAT, OVAL ROUND
SQUARE RECESS BITS
TAPPING/ SHEET METAL SCREW SIZE
0 1 2
0, 1
0, 1
0, 1
0, 1
0, 1
0, 1
MACHINE SCREW SIZE
WOOD SCREW SIZE
BIT SIZE
2, 3, 4 5, 6, 7, 8, 9
2, 3, 4
2, 3, 4 2, 3, 4 2, 3, 4, 5 2, 3, 4
5, 6, 7, 8, 9, 10
5, 6, 7, 8, 10
5, 6, 7, 8, 10 6, 8, 10 5, 6, 7, 8, 10
#0 #1 #2 #3
#3, #4
#3, #4
#3, #4
12, 1/4, 5/16
10, 12, 14, 16 12, 14, 16 12, 14 18, 20, 24 18, 20, 24 5/16, 3/8, 7/16, 1/2
3
12, 1/4
12, 14
#5, #6, #7 #5, #6, #7 #5, #6, #7 #8, #10 #8, #9, #10 #8, #10
3/8, 7/16, 1/2
5/16, 3/8, 7/16, 1/2
4
#12, #14 #12, #14
#12, #14
HEX KEYS/BITS
SOCKET HEAD SCREW SIZE
FLAT HEAD SIZE #1, #2 #3, #4 #5, #6
SET SCREW SIZE
SHOULDER SCREWS
PRESSURE PLUGS
BUTTON HEAD SIZE
POINT SIZE
.050 1/16
#0 #1
#1, #2 #3, #4
#1, #2 #3, #4 #5, #6
- - - - -
- - - - - - -
5/64 #2, #3 3/32 #4, #5
#8 #10
TORX KEYS/BITS
#8
#8
BIT SIZE
Socket Set Screw
Socket Cap Screw
Flat Head Screw
7/64 1/8 9/64 5/32 3/16 7/32 1/4 5/16
#6
-
-
-
-
1/4
#10
#10
1/4
T3 T4 T5 T6 T7 T8 T9
#8 #10 1/4 5/16 3/8 -
-
-
-
-
#2
- - - - - - -
- - -
5/16 3/8 7/16 1/2 5/8
1/4 5/16 3/8
1/4 5/16 3/8 7/16
5/16 3/8
1/16 1/8
-
#3 #4
-
-
-
1/2 5/8 3/4
1/4 3/8 1/2
#2 #3 #4 #5 #6 #8
1/2 5/8
1/2, 9/16
#5, #6
3/8 7/16, 1/2 3/4
5/8
#8
METRIC
-
SOCKET HEAD SCREW SIZE
BUTTON HEAD SIZE
SET SCREW SIZE
T10 T15 T20 T25 T27 T30 T40 T45 T50 T55
#10, #12
#4, #5
FLAT HEAD SIZE
SHOULDER SCREWS
POINT SIZE
-
#6
1/4
-
#10 #12
M2 M2.3, M2.5
M4 M5 M6 M8
M3 M4 M5 M6 M8
M3 M4 M5 M6 M8
- -
-
#8
M2.5
M3 M4 M5 M6 M8
5/16
#10, #12
1/4
M3 M4 M5 M6 M8
M6 M8
3/8
1/4
-
7/16
-
5/16, 3/8
M10
M10 M12 M16
1/2
5/16
-
M12, M14
M10 M12
M10 M12
- -
3/8
7/16
M10
M16
7/16, 1/2
1/2
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