Nut & Bolt Dimensions & Hardness Grade Identification

How to measure dimensions and determine
the hardness grade of hex bolts and nuts
Click on one of the tabs below to help you determine how to measure
the dimensions and hardness grade of hex bolts and nuts for SAE
sizes ¼” through 1½”.

  • Graded Nuts
    Dimensions
  • Graded Hex Bolt Dimensions –
    Partially Threaded
  • Graded Hex Bolt Dimensions –
    Fully Threaded
Nut Dimensions
Nominal Size or
Basic Major
Thread Diameter
(F) Width Across Flats
(G) Width Across
Corners
(H) Thickness
Basic
Max
Min
Max
Min
Basic
Max
Min
1/4
.2500
7/16
.438
.428
.505
.488
7/32
.226
.212
5/16
.3125
1/2
.500
.489
.577
.557
17/64
.273
.258
3/8
.3750
9/16
.562
.551
.650
.628
21/64
.337
.320
7/16
.4375
11/16
.688
.675
.794
.768
3/8
.385
.365
1/2
.5000
3/4
.750
.736
.866
.840
7/16
.448
.427
9/16
.5625
7/8
.875
.861
1.010
.982
31/64
.496
.473
5/8
.6250
15/16
.938
.922
1.083
1.051
35/64
.559
.535
3/4
.7500
1-1/8
1.125
1.088
1.299
1.240
41/64
.665
.617
7/8
.8750
1-5/16
1.312
1.269
1.516
1.447
3/4
.776
.724
1
1.0000
1-1/2
1.500
1.450
1.732
1.653
55/64
.887
.831
1-1/8
1.1250
1-11/16
1.688
1.631
1.949
1.859
31/32
.999
.939
1-1/2
1.500
2-1/4
2.250
2.175
2.598
2.480
1-9/32
1.317
1.245

Hex Bolt Dimensions
Nominal or Basic
Product Dia.
(E) Body
Diameter
(F) Width
Across Flats
(G) Width Across Corners
Max
Min
Basic
Max
Min
Max
Min
1/4
5/16
3/8
7/16
0.2500
0.3125
0.3750
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
1/2
9/16
5/8
3/4
0.5000
0.5625
0.6250
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
7/8
1
1-1/8
1-1/4
0.8750
1.0000
1.1250
1.2500
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
1-3/8
1-1/2
1.3750
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

(H) Head Height
(R) Radius of Fillet
Thread Length
Basic
Max
Min
Min
For Screws Lengths < 6 in.
For Screw Lengths > 6 in.
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
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
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
27/32
15/16
0.878
0.974
0.810
0.902
0.060
0.060
3.000
3.250
3.250
3.500

Fully Threaded Hex Bolt Dimensions

Nominal or Basic Product Dia.
(E) Body Diameter
(F) Width Across Flats
(G) Width Across Corners
(H) Head Height
Max
Min
Basic
Max
Min
Max
Min
Basic
Max
Min
1/4
5/16
3/8
7/16
0.2500
0.3125
0.3750
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
9/16
5/8
3/4
0.5000
0.5625
0.6250
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
1
1-1/8
1-1/4
0.8750
1.0000
1.1250
1.2500
0.8750
1.0000
1.1250
1.2500
0.8660
0.9900
1.1140
1.2390
1-15/16
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
1-3/8
1-1/2
1.3750
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