Lag screws are designed to bite deeply into wood, but how well they perform depends heavily on the pilot hole beneath them. A pilot hole that’s too small can split the wood or make installation unnecessarily difficult, while one that’s too large can reduce holding strength. This chart focuses specifically on lag screw pilot hole diameters, giving recommended sizes based on common lag screw diameters and typical wood conditions.
| Lag Screw Size | Softwood Pilot Hole | Hardwood Pilot Hole |
|---|---|---|
| 1/4″ | 1/8″ | 3/16″ |
| 5/16″ | 3/16″ | 1/4″ |
| 3/8″ | 1/4″ | 5/16″ |
| 7/16″ | 5/16″ | 3/8″ |
| 1/2″ | 3/8″ | 7/16″ |
| 9/16″ | 7/16″ | 1/2″ |
| 5/8″ | 1/2″ | 9/16″ |
| 3/4″ | 5/8″ | 11/16″ |
| 7/8″ | 11/16″ | 3/4″ |
| 1″ | 3/4″ | 7/8″ |
| 1-1/8″ | 7/8″ | 15/16″ |
| 1-1/4″ | 15/16″ | 1″ |
MISUMI USA carries a wide range of industrial manufacturing components – including Lag Screws– for your next project or machine fix. If you have any questions about measurement or sizing for your Lag Screw needs, feel free to connect with our product experts, and engineers. Also, if you are looking for more insights be sure to check out our other blog articles, including: Wood Screw Pilot Hole Sizes, Wood Screw Diameter Table, and more.
Author: Scott Bredemann | Updated: 12/30/2025
Disclaimer:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements.