SAE Bolts, Nuts & Washers

This table presents the most commonly used small to medium size varieties of SAE hardware. There are two general types of SAE bolts (sometimes referred to as machine screws). UNF (fine thread pitch) has more threads per inch than the same diameter bolt in the UNC (coarse thread pitch). Nut dimensions are maximums per SAE. Washer dimensions are for the regular size (vs. narrow or wide). All dimensions are in inches. Be aware that a search for hardware dimensions will yield variable results since many reported dimensions are manufacturers' production values, not necessarily the official SAE/ANSI values.

Note: For critical applications, consult official SAE/ANSI manuals to obtain dimensions.

Click here for a table of metric hardware sizes.

Size -

Threads

/Inch

Series Tap

Drill

Clearance Drill Nut

Points

Nut

Flats

Washer

I.D.

Washer

O.D.

Decimal (inches) Number
0-80 UNF 0.046 0.070 50 0.180 0.156 0.068 0.188
1-64 UNC 0.056 0.081 46 0.180 0.156 0.084 0.219
1-72 UNF 0.058 0.081 46 0.180 0.156 0.084 0.219
2-56 UNC 0.067 0.096 41 0.217 0.187 0.094 0.250
2-64 UNF 0.069 0.096 41 0.217 0.187 0.094 0.250
3-48 UNC 0.076 0.110 35 0.217 0.187 0.109 0.312
3-56 UNF 0.080 0.110 35 0.217 0.187 0.109 0.312
4-40 UNC 0.085 0.129 30 0.289 0.250 0.125 0.375
4-48 UNF 0.089 0.129 30 0.289 0.250 0.125 0.375
5-40 UNC 0.098 0.136 29 0.289 0.250 0.141 0.406
5-44 UNF 0.100 0.136 29 0.289 0.250 0.141 0.406
6-32 UNC 0.104 0.150 25 0.361 0.312 0.156 0.438
6-40 UNF 0.111 0.150 25 0.361 0.312 0.156 0.438
8-32 UNC 0.130 0.177 16 0.397 0.344 0.188 0.500
8-36 UNF 0.134 0.177 16 0.397 0.344 0.188 0.500
10-24 UNC 0.145 0.201 7 0.433 0.375 0.203 0.562
10-32 UNF 0.156 0.201 7 0.433 0.375 0.203 0.562
12-24 UNC 0.171 0.228 1 0.433 0.438 0.234 0.625
12-28 UNF 0.177 0.228 1 0.433 0.438 0.234 0.625
1/4-20 UNC 0.196 0.266 H 0.505 0.438 0.281 0.734
1/4-28 UNF 0.211 0.266 H 0.505 0.438 0.281 0.734
5/16-18 UNC 0.252 0.332 Q 0.577 0.500 0.344 0.875
5/16-24 UNF 0.267 0.332 Q 0.577 0.500 0.344 0.875
3/8-16 UNC 0.307 0.397 X 0.650 0.562 0.406 1.000
3/8-24 UNF 0.330 0.397 X 0.650 0.562 0.406 1.000
7/16-14 UNC 0.360 0.469 15/32 0.794 0.688 0.469 1.125
7/16-20 UNF 0.383 0.469 15/32 0.794 0.688 0.469 1.125
1/2-13 UNC 0.417 0.531 17/32 0.866 0.750 0.531 1.250
1/2-20 UNF 0.446 0.531 17/32 0.866 0.750 0.531 1.250
9/16-12 UNC 0.472 0.594 19/32 1.010 0.875 0.594 1.469
9/16-18 UNF 0.502 0.594 19/32 1.010 0.875 0.594 1.469
5/8-11 UNC 0.527 0.656 21/32 1.083 0.938 0.656 1.750
5/8-18 UNF 0.565 0.656 21/32 1.083 0.938 0.656 1.750
3/4-10 UNC 0.642 0.781 25/32 1.299 1.125 0.812 2.000
3/4-16 UNF 0.682 0.781 25/32 1.299 1.125 0.812 2.000
7/8-9 UNC 0.755 0.906 29/32 1.516 1.312 0.938 2.250
7/8-14 UNF 0.798 0.906 29/32 1.516 1.312 0.938 2.250
1-8 UNC 0.865 1.031 1 1/32 1.732 1.500 1.062 2.500
1-12 UNF 0.910 1.031 1 1/32 1.732 1.500 1.062 2.500
1-14 UN   1.031 1 1/32 1.732 1.500 1.062 2.500
1 1/8-7 UNC 0.970 1.156 1 5/32 1.949 1.688 1.188 2.750
1 1/8-8 UN   1.156 1 5/32 1.949 1.688 1.188 2.750
1 1/8-12 UNF 1.035 1.156 1 5/32 1.949 1.688 1.188 2.750
1 1/4-7 UNC 1.095 1.281 1 9/32 2.165 1.875 1.310 3.000
1 1/4-8 UN   1.281 1 9/32 2.165 1.875 1.310 3.000
1 1/4-12 UNF 1.160 1.281 1 9/32 2.165 1.875 1.310 3.000
1 3/8-6 UNC 1.195 1.406 1 13/32 2.382 2.062 1.438 3.250
1 3/8-8 UN   1.406 1 13/32 2.382 2.062 1.438 3.250
1 3/8-12 UNF 1.285 1.406 1 13/32 2.382 2.062 1.438 3.250
1 1/2-6 UNC 1.320 1.531 1 17/32 2.598 2.250 1.562 3.500
1 1/2-8 UN   1.531 1 17/32 2.598 2.250 1.562 3.500
1 1/2-12 UNC 1.410 1.531 1 17/32 2.598 2.250 1.562 3.500
1 5/8-8 UN   1.656 1 21/32 2.815 2.438 1.750 3.750
1 3/4-5 UNC 1.534 1.781 1 25/32 3.031 2.625 1.875 4.000
1 3/4-8 UN   1.781 1 25/32 3.031 2.625 1.875 4.000
1 7/8-8

2-4 1/2

2-8

2 1/4-4.5

2 1/4-8

UN

UNC

UN

UNC

UN

             
2 1/2-4

2 1/2-8

2 3/4-4

2 3/4-8

3-4

UNC

UN

UNC

UN

UNC

             
3-8

3 1/4-4

3 1/4-8

3 1/2-4

3 1/2-8

UN

UNC

UN

UNC

UN

             
3 3/4-4

3 3/4-8

4-4

4-8

UNC

UN

UNC

UN

             

1) See Drill Sizes page for cross reference.

2) Nut Points is the distance between opposite corners of hex nuts.

3) Nut Flats is the distance between opposite sides of hex nuts.