Bolt & Screw Thread Lengths
Imperial (inch)
|
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| Diameter (Inch) |
Nominal Thread Length Less Than 6" |
Nominal Thread Length Greater Than 6" |
A325 & A490 Thread Length |
| 1/4" | 0.75 | 1.00 | |
| 5/16" | 0.875 | 1.125 | |
| 3/8" | 1.00 | 1.25 | |
| 7/16" | 1.125 | 1.375 | |
| 1/2" | 1.25 | 1.5 | 1 |
| 9/16" | 1.375 | 1.625 | |
| 5/8" | 1.5 | 1.75 | 1.25 |
| 3/4" | 1.75 | 2 | 1.375 |
| 7/8" | 2 | 2.25 | 1.5 |
| 1" | 2.25 | 2.5 | 1.75 |
| 1-1/8" | 2.5 | 2.75 | 2 |
| 1-1/4" | 2.75 | 3 | 2 |
| 1-3/8" | 3 | 3.25 | 2.25 |
| 1-1/2" | 3.25 | 3.5 | 2.25 |
| 1-3/4" | 3.75 | 4 | |
| 2" | 4.25 | 4.5 | |
| 2-1/4" | 4.75 | 5 | |
| 2-1/2" | 5.25 | 5.5 | |
| 2-3/4" | 5.75 | 6 | |
| 3" | 6.25 | 6.5 | |
| 3-1/4" | 6.75 | 7 | |
| 3-1/2" | 7.25 | 7.5 | |
| 3-3/4" | 7.75 | 8 | |
| 4" | 8.25 | 8.5 | |
Metric Standard Thread Length for Bolts |
||
| Bolt Diameter (mm) | Standard Thread Length (mm) * | |
|---|---|---|
| Bolts 125mm and shorter | Bolts longer than 125mm | |
| 3 | 12 | - |
| 4 | 14 | - |
| 5 | 16 | 22 |
| 6 | 18 | 24 |
| 7 | 20 | 26 |
| 8 | 22 | 28 |
| 10 | 26 | 32 |
| 12 | 30 | 36 |
| 14 | 34 | 40 |
| 16 | 38 | 44 |
| 18 | 42 | 48 |
| 20 | 46 | 52 |
| * Important note: Some bolts may vary from the standard thread length. | ||
Trying to make sense of all the different screw and bolt thread lengths can be a real challenge—even for the most knowledgeable of professionals. Are you finding yourself a little confused, or do you need a quick refresher? Never let thread length get the best of you with our help from ASMC. We’ve put together a handy thread length chart that is certain to make quick work of confusion and increase work production.