How to determine the Thread Length of your Hex Cap Screws (Imperial/Metric) and Structural Bolts
Looking for the length of the bolt that would be the best for your project? We are here to help.
IMPERIAL (INCH) STANDARD THREAD LENGTH CHART FOR BOLTS |
|||
DIAMETER |
|||
NOMINAL THREAD LENGTH |
NOMINAL THREAD LENGTH |
A325 & A490 |
|
| (Inch) | 6″ and Less | Greater Than 6″ | Thread Length |
| 1/4″ | 0.75 | 1 | – |
| 5/16″ | 0.875 | 1.125 | – |
| 3/8″ | 1 | 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 (MM) STANDARD THREAD LENGTH CHART FOR BOLTS |
|||
BOLT DIAMETER |
STANDARD THEAD LENGTH (MM) * |
||
| (mm) | Bolts 125mm and shorter | Bolts >125mm and <125 | Bolts >200mm |
| M3 | 12 | – | – |
| M4 | 14 | – | – |
| M5 | 16 | 22 | 35 |
| M6 | 18 | 24 | 37 |
| M7 | 20 | 26 | 39 |
| M8 | 22 | 28 | 41 |
| M10 | 26 | 32 | 45 |
| M12 | 30 | 36 | 49 |
| M14 | 34 | 40 | 53 |
| M16 | 38 | 44 | 57 |
| M18 | 42 | 48 | 61 |
| M20 | 46 | 52 | 65 |
| M24 | 54 | 60 | 73 |
| M30 | 66 | 72 | 85 |
| M36 | 78 | 84 | 97 |
| M42 | 90 | 96 | 109 |
| M48 | 102 | 108 | 121 |
| M56 | – | 124 | 137 |
| M64 | – | 140 | 153 |
| M72 | – | 156 | 169 |
| M80 | – | 172 | 185 |
| M90 | – | 192 | 205 |
| M100 | – | 212 | 225 |
| *Please note: Per norm ANSI/ASME B18.2.3.5M-1989 | |||
Here are the maths you will need to do to determine the thread length you will get on standard Hex cap screws.
Tap bolts with full thread length might also be available in Imperial and Metric sizes.
Different type of Bolts : EG: Structural Bolts, Carriage Bolts and Lag Bolts will also have different rules for their respective thread length.
When in doubt , contact us at Boulonseclair@boulonseclair.com our team of professionnal will be more than happy to help you.