Lag Bolt vs. Carriage Bolt

It is always essential to know the different kinds of bolts perfect for your construction. Being aware of their differences and benefits will reduce your workload, making it faster and easier.

Lag bolts look like screws, and they have long lengths, which helps to fasten lumber pieces together in a construction project. Their sturdiness makes it possible for them to screw heavy materials with intense loads.

Carriage bolts can also be called plow bolts. These bolts are used in the fastening of wood to metal or metal to metal. They are designed so that the bolts cannot be removed through a wooden construction.

When picking between a lag bolt and a carriage bolt, you should know that they look different and can be used for various purposes. Lag bolts have round necks with hexagonal heads, while carriage bolts have square necks with domed heads.

Lag Bolt vs Carriage Bolt
 Lag BoltCarriage Bolt
Physical appearanceIt has a tapered threaded portion that stops at a particular part (half) of the bolt. They are steel with a hexagonal head (because of the strength needed to fix them) and round necks.It has a square neck, a rounded head, and a flat bottom. The threaded portion goes along part of its shank and is shaped like a cylinder. The shape of the bolt helps to keep it fastened after being installed.
PurposeIt is used to connect heavy pieces of lumber and other heavy-loaded materials.This is commonly used for fastening two pieces of wood together. You can also useit toattach metal to metal and wood to metal.
StrengthLag bolts are strong and can hold up to a thousand pounds when used in different applications, but they are less stronger than carriage bolts.A carriage bolt is also strong and can handle a higher weight capacity when compared to lag bolts.
RequirementLag bolts do not require washers or nuts. You do not need a drill as they can be directly screwed on.This requires a drilled hole before it can be inserted. It also requires washers and nuts.
UsesLag bolts can be used in the construction of decks and rafters. It is also commonly used in furniture, large timber construction, doorway constructions, etc.Carriage bolts are the better option for heavy-duty constructions. It can be used to wield heavy metal machines together and is also used in the construction of adock, and a swing set.

Related Articles

Stihl Wood Boss vs Farm Boss Chainsaw
Most Powerful Shop Vacs
Dust Collector Vs Shop Vac
Dewalt VS Ridgid Planer

Key Differences Between Lag Bolts and Carriage Bolts

To know which bolt is the best for your construction, you should know their differences. Some of them are listed below:


Since we know the different ways you can use these two bolts, it is essential to understand how to use them, which is easy and difficult. Lag bolts are easier to install because they have a pointed mouth and can be directly screwed on.

To install lag bolts, you should first mark your materials then drill a pilot hole through the materials. The smaller the pilot hole, the easier it will be for the lag screw to get in. You can also use a ‘lag screwdriver drill bit,’ allowing faster installations.

Carriage bolts require washers and nuts for proper installation because of their size. To install carriage bolts, you need to drill an appropriately sized hole into the wood, use a hammer to set the bolt in, and put a washer that helps to tighten the bolt.


The higher the strength of the bolt, the more weight it can support. Regarding power, lag bolts and carriage bolts are relatively high, but carriage bolts tend to be stronger because they use nuts and washers, which increases the tightness.

Lag bolts are powerful and durable, making them a good option for heavy-duty constructions. They are also ideal for woodworking as they were initially used to fasten wooden lags. The long length of lag bolts helps to provide a long-lasting connection.

Carriage bolts are equally as vital as Lag bolts, with the washers and nuts providing additional strength and support. Grade five carriage bolts have a tensile strength of 120,000 psi and are made from carbon steel. They are also capable of holding together large amounts of weight.

It all comes down to the application used by both bolts. This determined their level of capacity.

Similarities Between Lag Bolts and Carriage Bolts

A similar thing we can pinpoint between these two bolts is that they are usually used for the same purpose: to fasten things together. They are also used for woodworking purposes.

Other than that, they are entirely different regarding their appearance and application.


The purpose of a bolt is to fasten or hold materials together. They are used to position these materials in one place. Lag bolts are used to secure lumber pieces together, and they can also be used to attach steel shapes to wood structures.

Carriage bolts are also used to hold materials together. They are perfect for attaching metal materials to wooden structures and metal structures. Both bolts can be used for the same purpose but in different applications.

Pros and Cons of Lag Bolts


  • They are thicker than regular wood screws.
  • They are available in a wide variety of sizes and lengths.
  • The length of lag bolts makes them long-lasting.
  • They are highly durable and can handle heavyweight.
  • They offer a high level of performance because of their thickness and height.


  • Majority of the Lag screws are generic.
  • The wood can split if the lag screws are not installed correctly.

Pros and Cons of Carriage Bolts


  • The washers and nuts provide additional strength.
  • Carriage bolts are strong and can handle a lot of weight.
  • They are used for the effective fastening of two different metal components.
  • They have an excellent aesthetic appeal.


  • Their flat bottoms make fastening them slightly difficult.
  • Their round head shape makes them wrong for drill adaptors and torque wrenches.


Now you know the differences between Lag bolts and Carriage bolts. When choosing bolts, you should always consider the size, material, and purpose. This way, you know which is the best choice for your construction.

Leave a Comment

Your email address will not be published.