Understanding Standard Size Dimensions
The Size Dimension pertains to diameter of screws, bolts, & pins and inner diameter of nuts and washers. You may search for your product based on diameter by selecting a measurement on the Size dropdown. Other size measurements, such as screw, bolts, pin length, the outer diameters of nuts & washers, etc., appear on the search result itself.
A. Parts that Require Matching with a Mating Item
For example: Screws or bolts that drill through nuts, washers
Those parts that require matching with a mating item - screws or bolts with nuts or washers - have diameters that are denominated in actual inches or fractions thereof, followed by the number of threads per inch.
Screws and bolts that mate with a nut, as well as the nuts themselves, are denominated as such. Washers are not.
It is important to note that when matching a washer with a screw or a bolt, the diameter of the shaft of the screw or bolt should be matched to the inner diameter of the washer. For example, a ¾-16 bolt should be matched with a ¾ washer. The inner diameter of the ¾” washer will, in fact, be slightly larger than ¾” thereby enabling the washer to fit around the bolt. Consequently, when ordering a washer for a use other than matching it to a screw or a bolt, one should determine the actual inner iameter of the washer before placing an order.
Examples:
1. A fraction followed by a hyphen, followed by a number:
The fraction is the diameter of the shaft, in fraction of an inch. The number following the hyphen is the number of threads per inch, that is, the number of threads on the shaft itself, per inch of shaft length.
1/4-20: One quarter inch shaft diameter, 20 threads per inch
3/4-16: Three quarter inch shaft diameter, 16 threads per inch
2. For parts 1 inch or larger:
A number 1 or number larger than one, or number one or number larger than one followed by a fraction, then followed by a hyphen then a fraction or whole number:
The number 1 or number larger than one, or number one or number larger than one followed by a fraction, is the diameter of the shaft. The number following the hyphen is the number of threads per inch; that is, the number of threads on the shaft itself, per inch of shaft length. Same as for smaller parts.
1-12: One inch shaft diameter, 12 threads per inch
2-1/4-4-1/2: Two and one quarter inch shaft diameter, four and a half threads per inch
Note: The diameters of some smaller machine screws (though they may take a mating part), are denominated with the industry Numeric Size system described below. See section C below for clarification.
B. Parts that do not Require Matching with a Mating Item
Those parts that do not require matching with a mating item - screws or bolts that simply drill into or through a surface - are often denominated by industry Numeric Sizes preceded by a # sign. These do not show a number of threads-per-inch designation. These industry Numeric Sizes run from #0 through #15, with #0 the smallest and #15 the largest.
These Numeric Sizes are shaft diameters (and inner diameters of some washers) that were standardized years ago by the American Society of Mechanical Engineers (ASME), American Society of Testing & Materials (ASTM), and other standards bodies. These sizes were standardized based on sizes already commonly in use in the market.
1. Examples:
An industry Numeric Size, preceded by a # sign:
#6: A Number 6 size (sheet metal screws, Teks screws, drywall screws, particle board screws, wood screws, U-drive screws)
#8: A Number 8 size (sheet metal screws, Teks screws, drywall screws, particle board screws, wood screws, U-drive screws)
#14: A Number 14 size (sheet metal screws, Teks screws, wood screws)
2. Basic Major Diameters of industry Numeric Size-denominated screws:
(in inches)
#0: 0.0600 or 3/50 in
#1: 0.0730 or 73/1000 in
#2: 0.0860 or 43/500 in
#3: 0.0990 or 99/1000 in
#4: 0.1120 or 14/125 in
#5: 0.1250 or 1/8 in
#6: 0.1380 or 69/500 in
#7: 0.151 or 77/512
#8: 0.1640 or 41/250 in
#9: 0.1770 or 11/64 in
#10: 0.1900 or 19/100 in
#12: 0.2160 or 27/125 in
#14: 0.2500 or 1/4 in
#15: 0.3120 or 5/16 in
#16: 0.3750 or 3/8 in
Numeric Size denominations larger than #16 are uncommon.
Diameters are based on ASME Coarse Thread Series (UNC/UNRC) and ASME Fine Thread Series (UNF/UNRF)
C. Machine Screw Diameters denominated with the industry Numeric Size system
The diameters of smaller machine screws are denominated with the same Basic Major Diameters of industry Numeric Size-denominated screws noted in section B. 2. above, but with a number of threads per inch count as well. Here follows a list, in inches:
2-56: 0.0860 or 43/500 in diameter; 56 threads per inch
4-40: 0.1120 or 14/125 in diameter; 40 threads per inch
5-40: 0.1250 or 1/8 in diameter; 40 threads per inch
6-32: 0.1380 or 69/500 in diameter; 32 threads per inch
8-32: 0.1640 or 41/250 in diameter; 32 threads per inch
10-32: 0.1900 or 19/100 in diameter; 32 threads per inch
10-24: 0.1900 or 19/100 in diameter; 24 threads per inch
12-24: 0.2160 or 27/125 in diameter; 24 threads per inch
Guide to Fastener Materials |
Note: Steel low-carbon is generally the default steel selection when no other steel grade is specified, or when no higher grade steel is required. Please check your application needs if you are not certain.
Mechanical Guidelines for Fasteners - Screws, Nuts, Bolts, Washers, Pins
| Steel Grade |
Material & Treatment |
Proof Load Stress |
Yield Strength |
Tensile Strength |
Core Hardness, Rockwell |
Standards Authority |
|
|
ksi (1000 lbs/sq inch) Min. |
ksi (1000 lbs/sq inch) Min. |
ksi (1000 lbs/sq inch) Min. |
|
|
Low-carbon grade 2 |
Low/medium carbon steel, cold-forged |
55 |
57 |
74 |
B70-B100 |
Society of Automotive Engineers |
Grade A |
Low/medium carbon steel |
90-100 |
95-105 |
60 |
B69-B100 |
American Society for Testing & Materials |
Grade B |
Low/medium carbon steel |
70-133 |
76-139 |
60-100 |
B69-B95 |
American Society for Testing & Materials |
Grade 5 |
Medium carbon steel, quenched & tempered |
74-85 |
81-82 |
105-120 |
C19-C34 |
Society of Automotive Engineers |
Grade 8 |
Medium carbon alloy steel, quenched & tempered |
120 |
130 |
150 |
C33-C39 |
Society of Automotive Engineers |
Grade C |
Medium carbon steel |
144 |
154 |
N/A |
B78-C38 |
American Society for Testing & Materials |
2-H |
Medium carbon steel |
144 |
154 |
N/A |
B78-C38 |
Society of Automotive Engineers |
Strength guidelines may vary by part thickness, number of threads/inch, finish, and other design or production factors. |
InStock Fasteners publishes this list to serve as a guideline to the materials we market. InStock Fasteners makes no warranty of any kind as to the certification of parts sold meeting these specifications. |
Guide to Screw Points |
Type A: Found on Sheet Metal (Tapping) Screws
Type A tapping screws have coarse threads and gimlet points. They are used in thin metal, resinous plywood, and various composite boards.
Type AB: Found on Sheet Metal (Tapping) Screws
Type AB tapping screws have spaced threads and gimlet points. Like the Type A, they are used in thin metal, resinous plywood, and various composite boards. Type AB screws offer a wider range of applications over Type A screws.
Type B: Found on Sheet Metal (Tapping) Screws
Type B tapping screws have spaced threads and a blunt point with incomplete entering threads. They are used in thin metal, nonferrous castings, resinous plywood, plastics, and various composite boards.
Type 25: Found on Thread Cutting Screws
Also known as Type BT, Type 25 screws have spaced, incomplete tapered threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. They are used in plastic, asbestos compositions, and other composites.
Type F: Found on Thread Cutting Screws
Type F screws have machine screw threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. They are used in nonferrous castings, steel sheets, plastics, brass, cast iron, etc.
Type 23: Found on Thread Cutting Screws
Also known as Type T, Type 23 screws have machine screw threads with a blunt point and tapered entering edges, with one or more cutting edges and chip removal indentations. In this sense they are similar to Type F screws. The cutting edge on the point, however, is broader and deeper than that of the Type F. Type 23 screws are also used in nonferrous castings, steel sheets, plastics, brass, cast iron, etc.
Type 17: Found on Thread Cutting Screws
A thread cutting screw especially for wood, with a coarse tapping screw thread and a special long sharp point fluted to capture chips.
Teks screw (Self-Drilling Screw) |
|
|
Type 2 |
Type 3 |
Teks screws, also known as self drilling screws, drill their own hole in thin sheet metal, heavier gauge metals and other materials, then form close mating threads in the hole. The Teks screw is ideal for automated assembly and reduces or eliminates the need for drill bits or taps. Once the hole is drilled, Teks screws (self drilling screws) tap the hole in the same way as thread forming or thread cutting screws do in a pre-drilled hole. They are also designed to eliminate paint build-up, weld flash, or foreign material that may occur in pre-drilled or pre-punched holes.
Type U-drive:
U-Drive screws are round head metallic drive screws having multiple start threads of large helix angle, with a pivot. Featuring case-hardened threads, designed to be harder than the mating part. The Type U-Drive Screw is used when an attachment is not meant to be removed. It is driven into an undersized hole for great adherence, usually in metals or plastics. U-Drive Screws also have a round, unslotted head, again intended for a permanent fixture.
Fasteners' Inches to Metric Conversion Chart |
|
Inches |
Inches |
Millimeters |
Centimeters |
Meters |
|
Fractional |
Decimal |
|
|
|
|
1/64 |
0.0156 |
0.3969 |
0.03969 |
0.000397 |
|
1/32 |
0.0312 |
0.7925 |
0.07925 |
0.000793 |
|
3/64 |
0.0469 |
1.1906 |
0.11906 |
0.001191 |
1/16 |
1/16 |
0.0625 |
1.5875 |
0.15875 |
0.001588 |
|
5/64 |
0.0781 |
1.9844 |
0.19844 |
0.001984 |
|
3/32 |
0.0938 |
2.3813 |
0.23813 |
0.002381 |
|
7/64 |
0.1094 |
2.7781 |
0.27781 |
0.002778 |
1/8 |
1/8 |
0.1250 |
3.1750 |
0.3175 |
0.003175 |
|
9/64 |
0.1406 |
3.5719 |
0.35719 |
0.003572 |
|
5/32 |
0.1562 |
3.9675 |
0.39675 |
0.003968 |
|
11/64 |
0.1719 |
4.3656 |
0.43656 |
0.004366 |
3/16 |
3/16 |
0.1875 |
4.7625 |
0.47625 |
0.004763 |
|
13/64 |
0.2031 |
5.1594 |
0.51594 |
0.005159 |
|
7/32 |
0.2188 |
5.5563 |
0.55563 |
0.005556 |
|
15/64 |
0.2344 |
5.9531 |
0.59531 |
0.005953 |
1/4 |
1/4 |
0.2500 |
6.3500 |
0.635 |
0.00635 |
|
17/64 |
0.2656 |
6.7469 |
0.67469 |
0.006747 |
|
9/32 |
0.2812 |
7.1425 |
0.71425 |
0.007143 |
|
19/64 |
0.2969 |
7.5406 |
0.75406 |
0.007541 |
5/16 |
5/16 |
0.3125 |
7.9375 |
0.79375 |
0.007938 |
|
21/64 |
0.3281 |
8.3344 |
0.83344 |
0.008334 |
|
11/32 |
0.3438 |
8.7313 |
0.87313 |
0.008731 |
|
23/64 |
0.3594 |
9.1281 |
0.91281 |
0.009128 |
3/8 |
3/8 |
0.3750 |
9.5250 |
0.9525 |
0.009525 |
|
25/64 |
0.3906 |
9.9219 |
0.99219 |
0.009922 |
|
13/32 |
0.4062 |
10.3175 |
1.03175 |
0.010318 |
|
27/64 |
0.4219 |
10.7156 |
1.07156 |
0.010716 |
7/16 |
7/16 |
0.4375 |
11.1125 |
1.11125 |
0.011113 |
|
29/64 |
0.4531 |
11.5094 |
1.15094 |
0.011509 |
|
15/32 |
0.4688 |
11.9063 |
1.19063 |
0.011906 |
|
31/64 |
0.4844 |
12.3031 |
1.23031 |
0.012303 |
1/2 |
1/2 |
0.5000 |
12.7000 |
1.27 |
0.0127 |
|
33/64 |
0.5156 |
13.0969 |
1.30969 |
0.013097 |
|
17/32 |
0.5312 |
13.4925 |
1.34925 |
0.013493 |
|
35/64 |
0.5469 |
13.8906 |
1.38906 |
0.013891 |
9/16 |
9/16 |
0.5625 |
14.2875 |
1.42875 |
0.014288 |
|
37/64 |
0.5781 |
14.6844 |
1.46844 |
0.014684 |
|
19/32 |
0.5938 |
15.0813 |
1.50813 |
0.015081 |
|
39/64 |
0.6094 |
15.4781 |
1.54781 |
0.015478 |
5/8 |
5/8 |
0.6250 |
15.8750 |
1.5875 |
0.015875 |
|
41/64 |
0.6406 |
16.2719 |
1.62719 |
0.016272 |
|
21/32 |
0.6562 |
16.6675 |
1.66675 |
0.016668 |
|
43/64 |
0.6719 |
17.0656 |
1.70656 |
0.017066 |
11/16 |
11/16 |
0.6875 |
17.4625 |
1.74625 |
0.017463 |
|
45/64 |
0.7031 |
17.8594 |
1.78594 |
0.017859 |
|
23/32 |
0.7188 |
18.2563 |
1.82563 |
0.018256 |
|
47/64 |
0.7344 |
18.6531 |
1.86531 |
0.018653 |
3/4 |
3/4 |
0.7500 |
19.0500 |
1.905 |
0.01905 |
|
49/64 |
0.7656 |
19.4469 |
1.94469 |
0.019447 |
|
25/32 |
0.7812 |
19.8425 |
1.98425 |
0.019843 |
|
51/64 |
0.7969 |
20.2406 |
2.02406 |
0.020241 |
13/16 |
13/16 |
0.8125 |
20.6375 |
2.06375 |
0.020638 |
|
53/64 |
0.8281 |
21.0344 |
2.10344 |
0.021034 |
|
27/32 |
0.8438 |
21.4313 |
2.14313 |
0.021431 |
|
55/64 |
0.8594 |
21.8281 |
2.18281 |
0.021828 |
7/8 |
7/8 |
0.8750 |
22.2250 |
2.2225 |
0.022225 |
|
57/64 |
0.8906 |
22.6219 |
2.26219 |
0.022622 |
|
29/32 |
0.9062 |
23.0175 |
2.30175 |
0.023018 |
|
59/64 |
0.9219 |
23.4156 |
2.34156 |
0.023416 |
15/16 |
15/16 |
0.9375 |
23.8125 |
2.38125 |
0.023813 |
|
61/64 |
0.9531 |
24.2094 |
2.42094 |
0.024209 |
|
31/32 |
0.9688 |
24.6063 |
2.46063 |
0.024606 |
|
63/64 |
0.9844 |
25.0031 |
2.50031 |
0.025003 |
1 inch |
1 |
1.0000 |
25.4000 |
2.54 |
0.0254 |
6 inches |
6 |
6.0000 |
152.4000 |
15.24 |
0.1524 |
12 inches |
12 |
12.0000 |
304.8000 |
30.48 |
0.3048 |
24 inches |
24 |
24.0000 |
609.6000 |
60.96 |
0.6096 |
36 inches |
36 |
36.0000 |
914.4000 |
91.44 |
0.9144 |
Fasteners' Metric to Inches Conversion Chart |
Millimeters |
Inches |
Inches |
Centimeters |
Meters |
|
Decimal |
Fractional |
|
|
0.3969 |
0.0156 |
1/64 |
0.04 |
0.0004 |
0.7925 |
0.0312 |
1/32 |
0.08 |
0.0008 |
1.0000 |
0.0394 |
|
0.10 |
0.0010 |
1.5875 |
0.0625 |
1/16 |
0.16 |
0.0016 |
2.0000 |
0.0788 |
|
0.20 |
0.0020 |
3.1750 |
0.1251 |
1/8 |
0.32 |
0.0032 |
3.0000 |
0.1182 |
|
0.30 |
0.0030 |
4.0000 |
0.1576 |
|
0.40 |
0.0040 |
5.0000 |
0.1970 |
|
0.50 |
0.0050 |
6.3500 |
0.2502 |
1/4 |
0.64 |
0.0064 |
7.0000 |
0.2758 |
|
0.70 |
0.0070 |
8.0000 |
0.3152 |
|
0.80 |
0.0080 |
9.0000 |
0.3546 |
|
0.90 |
0.0090 |
9.5250 |
0.3753 |
3/8 |
0.95 |
0.0095 |
10.0000 |
0.3940 |
|
1.00 |
0.0100 |
11.0000 |
0.4334 |
|
1.10 |
0.0110 |
12.0000 |
0.4728 |
|
1.20 |
0.0120 |
12.7000 |
0.5004 |
1/2 |
1.27 |
0.0127 |
13.0000 |
0.5122 |
|
1.30 |
0.0130 |
14.0000 |
0.5516 |
|
1.40 |
0.0140 |
15.0000 |
0.5910 |
|
1.50 |
0.0150 |
15.8750 |
0.6255 |
5/8 |
1.59 |
0.0159 |
16.0000 |
0.6304 |
|
1.60 |
0.0160 |
17.0000 |
0.6698 |
|
1.70 |
0.0170 |
18.0000 |
0.7092 |
|
1.80 |
0.0180 |
19.0500 |
0.7506 |
3/4 |
1.91 |
0.0191 |
20.0000 |
0.7880 |
|
2.00 |
0.0200 |
22.2250 |
0.8757 |
7/8 |
2.22 |
0.0222 |
25.4000 |
1.0000 |
1 inch |
2.54 |
0.0254 |
30.0000 |
1.1820 |
|
3.00 |
0.0300 |
35.0000 |
1.3790 |
|
3.50 |
0.0350 |
40.0000 |
1.5760 |
|
4.00 |
0.0400 |
45.0000 |
1.7730 |
|
4.50 |
0.0450 |
50.0000 |
1.9700 |
|
5.00 |
0.0500 |
60.0000 |
2.3640 |
|
6.00 |
0.0600 |
70.0000 |
2.7580 |
|
7.00 |
0.0700 |
80.0000 |
3.1520 |
|
8.00 |
0.0800 |
90.0000 |
3.5460 |
|
9.00 |
0.0900 |
100.0000 |
3.9400 |
|
10.00 |
0.1000 |
110.0000 |
4.3340 |
|
11.00 |
0.1100 |
120.0000 |
4.7280 |
|
12.00 |
0.1200 |
130.0000 |
5.1220 |
|
13.00 |
0.1300 |
140.0000 |
5.5160 |
|
14.00 |
0.1400 |
150.0000 |
5.9100 |
|
15.00 |
0.1500 |
160.0000 |
6.3040 |
|
16.00 |
0.1600 |
170.0000 |
6.6980 |
|
17.00 |
0.1700 |
180.0000 |
7.0920 |
|
18.00 |
0.1800 |
190.0000 |
7.4860 |
|
19.00 |
0.1900 |
200.0000 |
7.8800 |
|
20.00 |
0.2000 |
220.0000 |
8.6680 |
|
22.00 |
0.2200 |
240.0000 |
9.4560 |
|
24.00 |
0.2400 |
260.0000 |
10.2440 |
|
26.00 |
0.2600 |
280.0000 |
11.0320 |
|
28.00 |
0.2800 |
300.0000 |
11.8200 |
|
30.00 |
0.3000 |
320.0000 |
12.6080 |
|
32.00 |
0.3200 |
340.0000 |
13.3960 |
|
34.00 |
0.3400 |
360.0000 |
14.1840 |
|
36.00 |
0.3600 |
400.0000 |
15.7600 |
|
40.00 |
0.4000 |
440.0000 |
17.3360 |
|
44.00 |
0.4400 |
480.0000 |
18.9120 |
|
48.00 |
0.4800 |
500.0000 |
19.7000 |
|
50.00 |
0.5000 |
750.0000 |
29.5500 |
|
75.00 |
0.7500 |
1000.0000 |
39.4000 |
|
100.00 |
1.0000 |
|
|
|
|
|
