Cap Screw Fasteners

A cap screw is a screw that has a thick wide head and a flat bottom toward the thread facing site. The hex head cap screw is the most common cap screw and is also the most common fastener in construction and machine assembly.

Our cap screws can be customized to your application and industry. Please review all of our standard cap screw charts below and download the size charts. 

Lag Screws

Hex Head

Hex Head Lag Screws
Basic Product Diameter Threads per Inch E F G H S
Body or Shoulder
Diameter
Width
Across
Flats

Hex Lag Screws

Shoulder Length
Width
Across
Corners
Head
Height
Max. Min. Basic Max. Min. Max. Min. Basic Max. Min. Min.
1/4 0.2500
5/16 0.3125
10
9
0.260
0.324
0.237
0.298
7/16
1/2
0.438
0.500
0.425
0.484
0.505
0.577
0.484
0.552
11/64
7/32
0.188
0.235
0.150
0.195
0.094
0.125
3/8 0.3750
7/16 0.4375
1/2 0.5000
7
7
6
0.388
0.452
0.515
0.360
0.421
0.482
9/16
5/8
3/4
0.562
0.625
0.750
0.544
0.603
0.725
0.650
0.722
0.866
0.620
0.687
0.826
1/4
19/64
11/32
0.268
0.316
0.364
0.226
0.272
0.302
0.125
0.156
0.156
5/8 0.6250
3/4 0.7500
5
4-1/2
0.642
0.768
0.605
0.729
15/16
1-1/8
0.938
1.125
0.906
1.088
1.083
1.299
1.033
1.240
27/64
1/2
0.444
0.524
0.378
0.455
0.312
0.375

Carriage Bolts

Round Head Square Neck Bolts

Hex Head Lag Screws
Basic Bolt
Diameter
E A H 0 P
Body
Diameter
Head
Diameter
Head
Height
Square
Width
Square
Depth
Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.
10 0.1900
1/4 0.2500
5/16 0.3125
3/8 0.3750
0.199
0.260
0.324
0.388
0.182
0.237
0.298
0.360
0.469
0.594
0.719
0.844
0.438
0.563
0.688
0.782
0.114
0.145
0.176
0.208
0.094
0.125
0.156
0.188
0.199
0.260
0.324
0.388
0.185
0.245
0.307
0.368
0.125
0.156
0.187
0.219
0.094
0.125
0.156
0.188
7/16 0.4375
1/2 0.5000
5/8 0.6250
3/4 0.7500
0.452
0.515
0.642
0.768
0.421
0.483
0.605
0.729
0.969
1.094
1.344
1.594
0.907
1.032
1.219
1.469
0.239
0.270
0.344
0.406
0.219
0.250
0.313
0.375
0.452
0.515
0.642
0.768
0.431
0.492
0.616
0.741
0.250
0.281
0.344
0.406
0.219
0.250
0.313
0.375

Dowel Screws

Hex Head Lag Screws
Size A B
Thread Length Collar Length
3/16-11 xl 1/2
  x2
  x2 1/2
  x3
  3/4  
  7/8  
  11/8  
  1 3/8  
   
  1/4  
  1/4  
  1/4  
1/4-10 xl 1/2
  x2
  x2 1/2
  x3
  x3 1/2
  3/4  
  7/8  
  11/8  
  1 3/8  
  1 5/8  
   
  1/4  
  1/4  
  1/4  
  1/4  
5/16-9 xl 1/2
  xl 3/4
  x2
  x2 1/2
  x3
  x3 1/2
  x4
  3/4  
  3/4  
  7/8  
  1 1/8  
  1 3/8  
  1 5/8  
  1 5/8  
   
  1/4  
  1/4  
  1/4  
  1/4  
  1/4  
  3/4  
3/8-7 x2 1/2
  x3
  x3 1/2
  x4
  1 1/8  
  1 3/8  
  1 5/8  
  1 5/8  
  1/4  
  1/4  
  1/4  
  3/4  

Elevator Bolts

Hex Head Lag Screws
Nominal Size or
Basic Bolt
Diameter
EBody
Diameter
A HHead
Height
0 P
Head Diameter Square
Width
Square
Depth
Max.
Edge
Sharp
Min.
Edge
Sharp
Min.
Edge
Flat
Max. Min. Max. Min. Max. Min. Max. Min.
1/4 0.2500
5/16 0.3125
3/8 0.3750
0.260
0.324
0.388
0.237
0.298
0.360
1.008
1.227
1.352
0.969
1.188
1.312
0.938
1.157
1.272
0.098
0.114
0.145
0.087
0.094
0.125
0.280
0.342
0.405
0.245
0.307
0.368
0.219 0.250 0.250 0.188
0.219
0.219

Tap Bolts

Hex Head Lag Screws
Nominal
Or Basic
E F G H
Body Diameter Width Across Flats Width Across Corners Head
Height
Product Diam. Max. Min. Basic Max. Min. Max. Min. Basic Max. Min.
1/4 0.2500
5/16 0.3125
3/8 0.3750
7/16 0.4375
0.2500
0.3125
0.3750
0.4375
0.2450
0.3065
0.3690
0.4305
7/16
1/2

9/16
5/8
0.438
0.500
0.562
0.625
0.428
0.489
0.551
0.612
0.505
0.577
0.650
0.722
0.488
0.557
0.628
0.698
5/32
13/64
15/64
9/32
0.163
0.211
0.243
0.291
0.150
0.195
0.226
0.272
1/2 0.5000
9/16 0.5625
5/8 0.6250
3/4 0.7500
0.5000
0.5625
0.6250
0.7500
0.4930
0.5545
0.6170
0.7410
3/4
13/16
15/16
1-1/8
0.750
0.812
0.938
1.125
0.736
0.798
0.922
1.100
0.866
0.938
1.083
1.299
0.840
0.910
1.051
1.254
5/16
23/64
25/64
15/32
0.323
0.371
0.403
0.483
0.302
0.348
0.378
0.455
7/8 0.8750
1 1.0000
1-1/8 1.1250
1-1/4 1.2500
0.8750
1.0000
1.1250
1.2500
0.8660
0.9900
1.1140
1.2390
1-5116
1-1/2
1-11/16
1-7/8
1.312
1.500
1.688
1.875
1.285
1.469
1.631
1.812
1.516
1.732
1.949
2.165
1.465
1.675
1.859
2.066
35/64
39/64
11/16
25/32
0.563
0.627
0.718
0.813
0.531
0.591
0.658
0.749
1-3/8 1.3750
1-1/2 1.5000
1.3750
1.5000
1.3630
1.4880
2-1/6
2-1/4
2.062
2.250
1.994
2.175
2.382
2.598
2.273
2.480
27/32
15/16
0.878
0.974
0.810
0.902

Head Plow Bolts

No.3

Hex Head Lag Screws
Hex Head Lag Screws
D A L S B
Nominal
Diameter of Bolt
Diameter of Head Feed Thickness Depth of Square and Head Width of Square
Max. Min.
Sharp
Abs. Min. With Flat Max. Max. Min. Max. Min.
(Basic)
3/8
7/16
0.708
0.826
0.671
0.781
0.656
0.766
0.031
0.036
0.312
0.364
0.281
0.328
0.387
0.450
0.375
0.438
1/2
5/8
3/4
0.945
1.147
1.303
0.890
1.094
1.250
0.875
1.063
1.219
0.042
0.050
0.050
0.417
0.506
0.541
0.375
0.456
0.491
0.515
0.640
0.765
0.500
0.625
0.750

Slotted Flat Countersunk

Head Cap Screws

Hex Head Lag Screws

Table 1 Dimensions of Slotted Flat Countersunk Head Cap Screws

Nominal
Size orBasic Screw Diameter
F A H J T R C B
Body Diameter Head Diameter Head Height Slot Width Slot Depth Fillet Radius Protrusion Above Gaging
Diameter
Gaging Dia.
Max, EdgeSharp Min,
Edge Rounded
or 
Flat
Max Min Ref Max Min Max Min Max Max Min
1/4 0.2500
5/16 0.3125
3/8 0.3750
1/16 0.4375
0.2500
0.3125
0.3750
0.4375
0.2450
0.3070
0.3690
0.4310
0.500
0.625
0.750
0.812
0.452
0.567
0.682
0.736
0.140
0.177
0.210
0.210
0.075
0.084
0.094
0.094
0.064
0.072
0.081
0.081
.0.68
0.086
0.103
0.103
0.045
0.057
0.068
0.068
0.100
0.125
0.150
0.175
0.046
0.053
0.060
0.065
0.030
0.035
0.040
0.044
0.424
0.538
0.651
0.703
1/2 0.5000
9/16 0.5625
5/8 0.6250
0.5000
0.5625
0.6250
0.4930
0.5550
0.6170
0.875
1.000
1.125
0.791
0.906
1.020
0.210
0.244
0.281
0.106
0.118
0.133
0.091
0.102
0.116
0.103
0.120
0.137
0.068
0.080
0.091
0.200
0.225
0.250
0.071
0.078
0.085
0.049
0.054
0.058
0.756
0.869
0.982
3/4 0.7500
7/8 0.8750
1 1.0000
0.7500
0.8750
1.0000
0.7420
0.8660
0.9900
1.375
1.625
1.875
1.251
1.480
1.711
0.352
0.423
0.494
0.149
0.167
0.188
0.131
0.147
0.166
0.171
0.206
0.240
0.115
0.138
0.162
0.300
0.350
0.400
0.099
0.113
0.127
0.068
0.077
0.087
1.208
1.435
1.661
1-1/8 1.1250
1-1/4 1.2500
1-3/8 1.3750
1-1/2 1.5000
1.1250
1.2500
1.3750
1.5000
1.1140
1.2390
1.3630
1.4880
2.062
2.312
2.562
2.812
1.880
2.110
2.340
2.570
0.529
0.600
0.665
0.742
0.196
0.211
0.226
0.258
0.178
0.193
0.208
0.240
0.257
0.291
0.326
0.360
0.173
0.197
0.220
0.244
0.450
0.500
0.550
0.600
0.141
0.155
0.169
0.183
0.096
0.105
0.115
0.124
1.826
2.052
2.279
2.505

Reliant Frame Bolts

Grade 8 Alloy

Hex Head Lag Screws
Nominal
Size Or Basic Major Dia. Of Thread
E F G B U H LT
Body Dia. Width Across Flats Width
Across
Corners
Flange
Dia.
Flange Thickness Head Height Thread Lngth.
L<6 In. L>6 In.
  Max. Min. Basic Max. Min. Max. Min. Max. Min. Max. Min. Basic
3/8 0.3750
1/2 0.5000
5/8 0.6250
3/4 0.7500
0.3750
0.5000
0.6250
0.7500
0.3690
0.4930
0.6170
0.7410
9/16
3/4
15/16
1-1/8
0.5625
0.7500
0.9375
1.1250
0.551
0.736
0.922
1.100
0.650
0.866
1.083
1.299
0.618
0.825
1.034
1.234
0.81
1.07
1.33
1.59
0.06
0.08
0.10
0.11
0.39
0.51
0.62
0.73
0.25
0.34
0.42
0.51
1.000
1.250 1.500 1.750
1.250
1.500
1.750
2.000

Hex Cap Screws

Hex Head Lag Screws
Nominal
Or Basic Product Dia.
E F G H R LT
Body Diameter Width Across Flats Width
Across
Corners
Head Height Radius of Fillet Thread Lngth.
For Screw Lengths< 6 In. For Screw Lengths > 6 In.
  Max. Min. Basic Max. Min. Max. Min. Basic Max. Min Min. Basic Basic
1/4 0.2500
5/16 0.3125
3/8 0.3750
7/16 0.4375
0.2500
0.3125
0.3750
0.4375
0.2450
0.3065
0.3690
0.4305
7/16
1/2
9/16
5/8
0.438
0.500
0.562
0.625
0.428
0.489
0.551
0.612
0.505
0.577
0.650
0.722
0.488
0.557
0.628
0.698
5/32
13/64
15/64
9/32
0.163
0.211
0.243
0.291
0.150
0.195
0.226
0.272
0.015
0.015
0.015
0.015
0.750
0.875 1.000 1.125
1.000
1.125
1.250
1.375
1/2 0.5000
9/16 0.5625
5/8 0.6250
3/4 0.7500
0.5000
0.5625
0.6250
0.7500
0.4930
0.5545
0.6170
0.7410
3/4
13/16
15/16
1-1/8
0.750
0.812
0.938
1.125
0.736
0.798
0.922
1.100
0.866
0.938
1.083
1.299
0.840
0.910
1.051
1.254
5/16
23/64
25/64
15/32
0.323
0.371
0.403
0.483
0.302
0.348
0.378
0.455
0.015
0.020
0.020
0.020
1.250
1.375
1.500
1.750
1.500
1.625
1.750
2.000
7/8 0.8750
1 1.0000
1-1/8 1.1250
1-1/4 1.250
0.8750
1.0000
1.1250
1.2500
0.8660
0.9900
1.1140
1.2390
1-5/16
1-1/2
1-11/16
1-7/8
1.312
1.500
1.688
1.875
1.285
1.469
1.631
1.812
1.516
1.732
1.949
2.165
1.465
1.675
1.859
2.066
35/64
39/64
11/16
25/32
0.563
0.627
0.718
0.813
0.531
0.591
0.658
0.749
0.040
0.060
0.060
0.060
2.000
2.250
2.500
2.750
2.250
2.500
2.750
3.000
1-3/8 1.3750
1-1/2 1.5000
1.3750
1.5000
1.3630
1.4880
2-1/6
2-1/4
2.062
2.250
1.994
2.175
2.382
2.598
2.273
2.480
27/32
15/16
0.878
0.974
0.810
0.902
0.060
0.060
3.000
3.250
3.250
3.500

HEX HEAD CAP SCREWS MECHANICAL AND MATERIAL REQUIREMENTS

GRADES 2, 5 & 8

Abstract of SAE J429 1985

Grade
Designa
tion
Products Nominal Size Dia.,
In.
Full Size
Bolts, Screws
Studs, Sems
Machine Test Specimens of
Bolts, Screws and Studs
Surface
Hardness
Core
Hardness
Grade
Identification
Marking L
Proof
Load (Stress)
psi
Tensile
Strength
(Stress)
Min.,psi
Yield
Strength
(Stress)
Min.,psi
Tensile
Strength
(Stress)
Min.,psi
Elonga-
tion Min., %
Reduction
of Area
Min, %
Rockwell
30N
Max.
Rockwell
Min. Max.
2 Bolts,
Screws, Studs
1/4 thru 3/4
Over 3/4 to 1-1/2
55,000

 

 

33,000

74,000

 

 

60,000

57,000

 

 

36,000

74,000

 

 

60,000

18

 

 

18

35

 

 

35

 

 

B80

 

 

B70

B100

 

 

B100

None
5 Bolts,
Screws, Studs
1/4 thru 3/4
Over 3/4 to 1-1/2
85,000

 

 

74,000

120,000

 

 

105,000

92,000

 

 

81,000

120,000

 

 

105,000

14

 

 

14

35

 

 

35

54

 

 

50

C25

 

 

C19

C34

 

 

C30

8 Bolts,
Screws, Studs
1/4 thru 1-1/2 120,000 150,000 130,000 150,000 12 35 58.6 C33 C39

Step Bolts

Hex Head Lag Screws
Nominal
Size
or Basic
Bolt Diameter
E A H O P
Body
Diameter
Head
Diameter
Head
Height
Square
Width
Square
Depth
Max. Min. Max. Min Max. Min Max. Min Max. Min
10 0.1900
1/4 0.2500
0.199
0.260
0.182
0.237
0.656
0.844
0.625
0.813
0.114
0.145
0.094
0.125
0.199
0.260
0.185
0.245
0.125
0.156
0.094
0.125
5/16 0.3125
3/8 0.3750
0.324
0.388
0.298
0.360
1.031
1.219
1.000
1.188
0.176
0.208
0.156
0.188
0.324
0.388
0.307
0.368
0.187
0.219
0.156
0.188

Hanger Bolts

Size A B C D
Standard
Length
Machine
Length
Lag
Thread Length
Center
Space
10-24 x1-1/2
  x1-3/4
  x2
  x2-1/2
  x3
  1-1/2  
  1-3/4  
  2  
  2-1/2  
  3  
  5/8  
  3/4  
  1  
  1  
  1-1/2  
  7/8  
  1  
  1  
  1-1/2  
  1-1/2  
   
   
   
   
   
1/4-20 x1-1/2
  x1-3/4
  x2
  x2-1/4
  x2-1/2
  x3
  x3-1/2
  x4
  x4-1/2
  x5
  x6
  1-1/2  
  1-3/4  
  2  
  2-1/4  
  2-1/2  
  3  
  3-1/2  
  4  
  4-1/2  
  5  
  6  
  1/2  
  3/4  
  1  
  1  
  1  
  1-1/2  
  1-1/2  
  2  
  1-1/8  
  1-1/8  
  1-1/4  
  3/4  
  1  
  1  
  1-1/4  
  1-1/2  
  1-1/2  
  2  
  2  
  3  
  3  
  3  
   
   
   
   
   
   
   
   
  3/8  
  7/8  
  1-3/4  
5/16-18 x1-1/2
  x1-3/4
  x2
  x2-1/4
  x2-1/2
  x2-3/4
  x3
  x3-1/2
  x4
  x4-1/2
  x5
  x5-1/2
  x6
  1-1/2  
  1-3/4  
  2  
  2-1/4  
  2-1/2  
  2-3/4  
  3  
  3-1/2  
  4  
  4-1/2  
  5  
  5-1/2  
  6  
  5/8  
  3/4  
  1  
  1  
  1  
  1-1/4  
  1-1/2  
  1-1/2  
  2  
  1-1/8  
  1-1/8  
  1-1/8  
  1-1/4  
  7/8  
  1  
  1  
  1-1/4  
  1-1/2  
  1-1/2  
  1-1/2  
  2  
  2  
  2  
  3  
  3  
  3  
   
   
   
   
   
   
   
   
   
  7/8  
  7/8  
  1-3/8  
  1-3/4  
3/8-16 x2
  x2-1/2
  x3
  x3-1/2
  x4
  x4-1/2
  x5
  x5-1/2
  x6
  x8
  x10
  2  
  2-1/2  
  3  
  3-1/2  
  4  
  4-1/2  
  5  
  5-1/2  
  6  
  8  
  10  
  1  
  1  
  1-1/2  
  1-1/2  
  2  
  1-1/8  
  1-1/8  
  1-1/8  
  1-1/4  
  2-1/2  
  2-1/2  
  1  
  1-1/2  
  1-1/2  
  2  
  2  
  3  
  3  
  3  
  3  
  3  
  3  
   
   
   
   
   
  3/8  
  3/8  
  1-3/8  
  1-3/8  
  2-1/2  
  4-1/2  

Serrated Flange Screws

Whiz-Lock® Equivalents

®Whiz-Lock is a registered trademark of the MacLean-Fogg Co.

Size W F
Width Across
Flats
Flange
Data
6
8
10
1/4
5/16
3/8
.187
.250
.312
.375
.500
.562
.260
.348
.433
.522
.696
.782