Fence Post Sizes: Which Size Is Right for Your Fence?

Fence posts offer stability and support for your fence—and often, the bigger they are, the stronger they are. So, how do you know which size is right for your fence? Here’s how to choose from the most common fence post sizes.

What Is the Standard Fence Post Size?

Fence post sizes depend on the fencing material. For example, on a wood fence, the posts are often 4 by 4 inches or 6 by 6 inches. Meanwhile, chain link fence posts are circular and are often 1 5/8 inches or 2 3/8 inches in diameter.

Fence Post Sizes by Type

Fence posts are often between 4 and 16 feet in length, but the other dimensions depend on the type of fence. Let’s look at the most common fence post sizes of different kinds of fences.

Wood Fence Post Sizes

For the most part, wood fence posts are square-shaped, with the most popular sizes being 4 by 4 inches and 6 by 6 inches. You can also find circular wood fence posts in similar sizes.

Vinyl Fence Post Sizes

Like wood fences, vinyl fence posts are often square as well. The most common size for these types of fence posts is 5 by 5 inches.

Aluminum Fence Post Sizes

Aluminum fence posts also come in a variety of sizes, but 2 by 2 inches and 3 by 3 inches are among the most common. 

Chain-Link Fence Post Sizes

Chain-link fence posts are circular—rather than square—so they’re a little bit different than the others on this list. They’re available in a range of sizes, but they’re often 1 5/8 or 2 3/8 inches in diameter.

How to Measure the Size of a Fence Post

If you have fence posts on your property but aren’t sure which size they are, you can measure them to find out. It depends on the design of your fence, but you’ll likely need to measure the fence posts at their tallest point (or where they rise above the other parts of the fence). If so, you may need a ladder.

Whichever way you approach it, here’s how to measure the size of a fence post:

• Square fence posts: With a tape measure, measure the width and depth of the fence post. In most cases, these measurements will be somewhere between 2 and 8 inches.

• Circular fence posts: Wrap your tape measure around the post to determine its circumference. Then, divide that figure by 3.14 to get its diameter. Again, most circular fence posts are 1 5/8 or 2 3/8 inches in diameter.

Heads up, though: If you need to measure a post’s height, you might have a hard time. Fence posts are often buried several feet deep, so it’s difficult to determine a post’s height if it’s partially underground.

Factors That Influence Fence Post Size

With multiple post sizes available for each kind of fence, how do you know which one is best for your fence? Here are the factors to consider when selecting a fence post size.

Type of Fence

As we’ve covered, fence post sizes are highly dependent on the type of fence you have. Wood and vinyl fence posts are bigger than aluminum and chain link ones. However, each type comes in a range of sizes, so there may be exceptions.

Type of Fence Post

Just like there are different kinds of fences, there are also multiple types of fence posts. These include:

• Line posts: These posts connect straight sections of your fence. 

• Corner posts: Placed at 90-degree angles, corner posts connect fencing that runs in different directions.

• Gate posts: These posts are designed to support the weight of a fence gate.

Corner and gate posts need to be more supportive than line posts—and as a result, they’re larger.

Also, in the case of gate posts: The wider the gate, the bigger the gate post should be. For example, gates between 3 and 6 feet wide should have 4-by-4-inch fence posts, while 10-foot-wide gates need 6-by-6-inch posts.

Spacing Between Posts

The spacing between your fence posts will also impact the size of the posts. For most types of fences, the gaps between posts should be 6 to 8 feet wide. If the space between your posts is wider than this, you’ll need thicker (and therefore stronger) fence posts.

What to Do If You Have the Wrong Size Fence Posts

Let’s say you’re planning to build a new fence on your property, and you’ve realized that your posts aren’t the right size. Depending on when and where you bought them, you may be able to exchange them for another size. Check the company’s return policy to find out.

If that’s not an option, see if you can redesign your fence to use the posts you purchased. For example, if the posts are smaller than you need, you might still be able to use them if you reduce the amount of spacing between posts.

If the fence is already up, your options may be more limited. While it’s possible to remove fence posts by yourself, it can be a rather difficult job—especially if they’re set in concrete. Plus, in order to remove the posts, you’ll have to take down most (if not all) of the other parts of the fence, too. In situations like these, it’s easier to call a fencing pro near you rather than trying to fix it alone.