Choosing the right size for lag and carriage bolts is key to ensuring your construction projects are strong and stable. This size chart will guide you in selecting the perfect bolts, considering various factors like diameter and length. Balancing these aspects helps avoid common issues and ensures optimal performance.
Lag & Carriage Bolts Size Chart
Carriage Bolt Dimensions
Here’s the table content formatted for clarity:
| Bolt Diameter | Body Diameter (E) Max | Body Diameter (E) Min | Head Diameter (A) Max | Head Diameter (A) Min | Head Height (H) Max | Head Height (H) Min | Square Width (O) Max | Square Width (O) Min | Square Depth (P) Max | Square Depth (P) Min | Corner Radius on Square (Q) Max | Fillet Radius (R) Max |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. 10 | 0.199 | 0.159 | 0.469 | 0.436 | 0.114 | 0.094 | 0.199 | 0.185 | 0.125 | 0.094 | 0.031 | 0.031 |
| 1/4″-0.1900 | 0.26 | 0.213 | 0.594 | 0.563 | 0.145 | 0.125 | 0.26 | 0.245 | 0.156 | 0.125 | 0.031 | 0.031 |
| 5/16″-0.2500 | 0.324 | 0.272 | 0.719 | 0.688 | 1.176 | 0.156 | 0.324 | 0.307 | 0.187 | 0.156 | 0.031 | 0.031 |
| 3/8″-0.3750 | 0.388 | 0.329 | 0.844 | 0.782 | 0.208 | 0.188 | 0.388 | 0.368 | 0.219 | 0.188 | 0.047 | 0.031 |
| 7/16″-0.4375 | 0.452 | 0.388 | 0.969 | 0.907 | 0.239 | 0.219 | 0.452 | 0.431 | 0.25 | 0.219 | 0.047 | 0.031 |
| 1/2″-0.500 | 0.515 | 0.444 | 1.094 | 1.032 | 0.27 | 0.25 | 0.515 | 0.492 | 0.281 | 0.25 | 0.047 | 0.031 |
| 5/8″-0.6250 | 0.642 | 0.559 | 1.344 | 1.219 | 0.344 | 0.313 | 0.642 | 0.616 | 0.344 | 0.313 | 0.078 | 0.062 |
| 3/4″-0.7500 | 0.768 | 0.678 | 1.594 | 1.469 | 0.406 | 0.375 | 0.768 | 0.741 | 0.406 | 0.375 | 0.078 | 0.062 |
| 7/8″-0.8750 | 0.895 | 0.795 | 1.844 | 1.719 | 0.459 | 0.438 | 0.895 | 0.895 | 0.469 | 0.438 | 0.094 | 0.062 |
| 1″-1.0000 | 1.022 | 0.91 | 2.094 | 1.969 | 0.531 | 0.5 | 1.022 | 0.99 | 0.531 | 0.5 | 0.094 | 0.062 |
Pilot Hole Diameter for Lag Bolts
| Bolt Dia | Shank (Unthreaded) | Pilot Hole Dia |
|---|---|---|
| 3/8 | 3/8 | 15/64 |
| 7/16 | 7/16 | 9/32 |
| 1/2 | 1/2 | 5/16 |
| 9/16 | 9/16 | 23/64 |
| 5/8 | 5/8 | 13/32 |
| 3/4 | 3/4 | 1/2 |
| 7/8 | 7/8 | 39/64 |
| 1 | 1 | 23/32 |
| 11/8 | 11/8 | 53/64 |
| 11/4 | 11/4 | 15/16 |
Hex Lag Screws Dimensions
| Bolt Diameter | Body/Shoulder Diameter (E) | Width Across the Flats (F) | Width Across Corners (G) | Head Height (H) | Shoulder Length (S) | Radius of Fillet (R) | ||||||||
| Max | Min | Basic | Max | Min | Max | Min | Basic | Max | Min | Min | Max | Min | ||
| No. 10 | 0.199 | 0.178 | 9/32 | 0.281 | 0.271 | 0.323 | 0.309 | 1/8 | 0.14 | 0.11 | 0.094 | 0.03 | 0.01 | |
| 1/4 | 0.26 | 0.237 | 7/16 | 0.438 | 0.425 | 0.505 | 0.484 | 11/64 | 0.188 | 0.15 | 0.094 | 0.03 | 0.01 | |
| 5/16 | 0.324 | 0.298 | 1/2 | 0.5 | 0.484 | 0.577 | 0.552 | 7/32 | 0.235 | 0.195 | 0.125 | 0.03 | 0.01 | |
| 3/8 | 0.388 | 0.36 | 9/16 | 0.562 | 0.544 | 0.65 | 0.62 | 1/4 | 0.268 | 0.226 | 0.125 | 0.03 | 0.01 | |
| 7/16 | 0.425 | 0.421 | 5/8 | 0.625 | 0.603 | 0.722 | 0.687 | 19/64 | 0.316 | 0.272 | 0.156 | 0.03 | 0.01 | |
| 1/2 | 0.515 | 0.482 | 3/4 | 0.75 | 0.725 | 0.866 | 0.826 | 11/32 | 0.364 | 0.302 | 0.156 | 0.03 | 0.01 | |
| 5/8 | 0.642 | 0.605 | 15/16 | 0.938 | 0.906 | 1.083 | 1.033 | 27/64 | 0.444 | 0.378 | 0.312 | 0.06 | 0.02 | |
| 3/4 | 0.768 | 0.729 | 1-1/8 | 1.125 | 1.088 | 1.299 | 1.24 | 1/2 | 0.524 | 0.455 | 0.375 | 0.06 | 0.02 | |
| 7/8 | 0.895 | 0.852 | 1-5/16 | 1.312 | 1.269 | 1.516 | 1.447 | 37/64 | 0.604 | 0.531 | 0.375 | 0.06 | 0.02 | |
| 1 | 1.022 | 0.976 | 1-1/2 | 1.5 | 1.45 | 1.732 | 1.653 | 43/64 | 0.7 | 0.591 | 0.625 | 0.09 | 0.03 | |
| 1-1/8 | 1.149 | 1.098 | 1-11/16 | 1.688 | 1.631 | 1.949 | 1.859 | 3/4 | 0.78 | 0.658 | 0.625 | 0.09 | 0.03 | |
| 1-1/2 | 1.277 | 1.223 | 1-7/8 | 1.875 | 1.812 | 2.165 | 2.066 | 27/32 | 0.876 | 0.749 | 0.625 | 0.09 | 0.03 | |
What Are Lag Bolts?
Lag bolts, often called lag screws, are robust fasteners designed for heavy-duty tasks in woodworking and construction. These bolts excel in securing large wooden beams and other materials due to their impressive holding strength. However, it’s crucial to balance factors like size and thread type to avoid issues such as insufficient grip or damage to the materials.
By understanding these trade-offs, you can ensure that your projects are not only secure but also durable. Making informed decisions about lag bolts helps prevent costly mistakes and enhances overall stability in your construction efforts.
Comparing Lag Bolts and Carriage Bolts
While lag and carriage bolts both secure materials effectively, they have unique features that make them suitable for different uses. Lag bolts are ideal for heavy-duty tasks due to their strong grip, but they require pre-drilling, which can be time-consuming.
On the other hand, carriage bolts, with their rounded heads and square shoulders, are easier to install and prevent rotation, but they may not handle as much load as lag bolts.
Understanding these trade-offs helps you choose the best fastener for your project’s needs, ensuring strength and efficiency while avoiding potential issues like inadequate holding power or installation difficulties.
Choosing the Right Bolt for Your Project
Selecting the right lag or carriage bolt hinges on several key factors, including the type of material you’re working with, the load requirements, and the installation environment. For instance, lag bolts are better for heavy loads but require pre-drilling, while carriage bolts are easier to install but may not support as much weight.
Balancing these factors involves weighing the strength and ease of installation against the specific demands of your project. By carefully considering these elements, you can make an informed choice that ensures durability and performance while minimizing potential issues.
FAQs
1: What is the difference between lag bolts and carriage bolts?
Answer: Lag bolts are heavy-duty fasteners used primarily for securing large wooden beams or heavy materials. They have a hexagonal head and require a pre-drilled hole. Carriage bolts, on the other hand, have a rounded head with a square shoulder underneath that prevents rotation once installed. They are often used in metal-to-wood or wood-to-wood connections. While lag bolts offer superior holding power, carriage bolts are easier to install and less likely to rotate.
FAQ 2: How do I choose the right size lag bolt for my project?
Answer: To select the appropriate size lag bolt, consider the material type, load requirements, and the thickness of the material. Measure the diameter and length of the bolt to ensure it fits well and provides the necessary holding strength. Larger diameters and longer lengths generally offer more holding power, but you must also consider if the material can accommodate the size without splitting. Consulting a size chart can help you match the bolt size to your specific project needs.
FAQ 3: Can carriage bolts be used in place of lag bolts?
Answer: While carriage bolts can be used in various applications, they may not always be a direct substitute for lag bolts. Carriage bolts are better suited for applications requiring easy installation and resistance to rotation, such as securing metal to wood. However, if you need a bolt with high holding power for heavy loads, lag bolts are more appropriate. Always assess the requirements of your project to determine which bolt type best meets your needs.