A post in a fence is an upright support structure that holds everything else up. Fence posts are typically installed by digging a hole and setting them in the ground, or by using concrete footings for added stability. Burying them partially underground is an important step in building a strong and stable fence.

Rails are the horizontal bars that are attached between the fence posts . They act like connecting beams, creating the actual barrier or enclosure of the fence.

How to calculate number of post for fence?

Fence length and post spacing information needed to calculate the number of fence posts are:

• Fence Length: This is the total linear distance the fence will cover.
• Post Spacing: This refers to the center-to-center distance between two fence posts.

Once you have the fence length and desired post spacing, you can use this formula to calculate the number of posts:

$\text{Number of posts}=\left(\frac{\text{Fence length}}{\text{Post spacing}}\right)+1$

Example:

Let's say your fence will be 50 feet long, and you decide on a post spacing of 8 feet.

• Number of posts = (50 feet / 8 feet) + 1
• Number of posts = 6.25 (we only care about whole posts, so we round up) + 1
• Number of posts = 7 + 1

Therefore, you would need 8 fence posts for this scenario.

Calculating the Number of Rails Needed for Your Fence

For standard fences (6 feet tall): Two rails are common, placed one near the top and another near the bottom for stability. 

For taller fences (8 feet or above): Three or even four rails might be needed, spaced evenly throughout the height.

First determine the number of fence sections: Once you've decided on post spacing (refer to previous discussion on calculating fence posts), you can calculate the number of sections.

Formula for determine the number of fence sections:

$\text{Number of sections}=\text{Number of posts}-1$

This is because there's one less section than the total number of posts since one post will be at the beginning and another at the end of the fence line, not requiring rails in between them.

Multiply the number of rails per section by the number of sections: This will give you the total number of rails needed for your fence.

Formula for rails:

$\text{Total number of rails}=\text{Number of rails per section}\times \text{Number of sections}$

Example:

Let's say your fence is 50 feet long, you'll use 8 feet post spacing, and you decide to go with two rails per section for a 6-foot tall fence.

Calculate number of post:

Number of posts = (50 feet / 8 feet) + 1

Number of posts = 6.25 (we only care about whole posts, so we round up) + 1

Number of posts = 7 + 1 = 8 posts

Calculate number of sections:

Number of sections = Number of posts - 1

Number of sections = 8 posts - 1

Number of sections  = 7 sections

Total number of rails = Number of rails per section × Number of sections = 2 rails/section × 7 sections = 14 rails

Therefore, you would need 14 rails for this scenario (assuming two rails per section).