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.

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Lag Screws

Hex Head

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Basic Product Diameter

Threads per Inch

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.

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

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Basic Bolt
Diameter

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

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Size

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

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Nominal Size or
Basic Bolt
Diameter

EBody
Diameter

HHead
Height

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

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Nominal
Or Basic

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

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D	A			L	S		B
Nominal Diameter of Bolt	Diameter of Head			Feed Thickness	Depth of Square and Head		Width of Square
Nominal Diameter of Bolt	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

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Table 1 Dimensions of Slotted Flat Countersunk Head Cap Screws

Nominal
Size orBasic Screw Diameter

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

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

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Nominal
Size Or Basic Major Dia. Of Thread

^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

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Nominal
Or Basic Product Dia.

^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

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

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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.

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

—

B80

B70

B100

None

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

C25

C19

C34

C30

Bolts,
Screws, Studs

1/4 thru 1-1/2

120,000

150,000

130,000

150,000

58.6

C33

C39

Step Bolts

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Nominal
Size
or Basic
Bolt Diameter

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

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Size

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.

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Download Size Chart

Size	W	F
Size	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

Cap Screw Fasteners

Lag Screws

Hex Head

Carriage Bolts

Round Head Square Neck Bolts

Dowel Screws

Elevator Bolts

Tap Bolts

Head Plow Bolts

No.3

Slotted Flat Countersunk

Head Cap Screws

Reliant Frame Bolts

Grade 8 Alloy

Hex Cap Screws

HEX HEAD CAP SCREWS MECHANICAL AND MATERIAL REQUIREMENTS

GRADES 2, 5 & 8

Step Bolts

Hanger Bolts

Serrated Flange Screws

Whiz-Lock® Equivalents

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