Fence post calculator
Work out how many posts a fence run needs and the concrete to set them.
Fence post calculator
Work out how many posts a fence run needs and the concrete to set them.
Enter your fence length and post spacing to see the post count.
Posts needed
Project summary
How it works
These are material estimates, not a structural design. Check local code, property lines and utility locations, and frost depth requirements, before digging.
Fence post calculator
Posts come from length divided by spacing, plus one
A fence run divides into sections by post spacing, and every section needs a post at each end, so the post count is always one more than the number of sections. A 100 foot fence at 8 foot spacing has 13 sections and 14 posts, not 13: it is a detail worth getting right before ordering, since a missing post means a return trip to the supplier.
Concrete accounts for what the post displaces
The concrete figure here is the hole volume minus the volume the post itself takes up, not the full hole, since the post displaces some of what would otherwise be concrete. Hole depth should be set from local frost depth and code requirements rather than assumed, which is why this calculator asks for it directly instead of guessing.
Frequently asked questions
How many fence posts do I need for 100 feet of fence?
At the common 8 foot post spacing, 100 feet of fence needs 14 posts: 13 sections plus one extra post to close both ends. Tighter spacing means more posts; enter your own fence length and spacing above for the exact count.
How deep should a fence post hole be?
Depth depends on the local frost line and the height and load of the fence, and is set by local building code rather than one universal number; many residential fence posts are set 24 to 36 inches deep, but check with your local building department before digging.
How many fence posts do I need for 200 feet of fence?
At 8 foot spacing, you need 26 posts for a straight 200 foot run. The calculator divides the fence length by your chosen spacing, rounds up, and adds one for the end post. For corners, each corner adds one extra post.
What size posts do I need for a fence?
Most wood fences use 4 by 4 posts for sections up to 8 feet tall. Taller privacy fences or those in windy areas benefit from 6 by 6 posts. The calculator counts posts, and you select the size based on your fence height and local wind load conditions.
How deep should fence posts be set?
A common rule of thumb is to bury one third of the post length. For a 6 foot fence, that means a 9 foot post buried 3 feet deep. In frost zones, posts should extend below the frost line. The calculator counts posts, and you choose the post length and depth your conditions require.
Do I need concrete for fence posts?
Concrete at the base of each post adds significant stability, especially for tall fences or loose soil. Many builders use gravel at the bottom for drainage and concrete for the upper portion. In some soil types, compacted gravel alone is sufficient. Check your local building code for post setting requirements.
What is the difference between line, corner and end posts?
Line posts run along a straight section. Corner posts are at a change of direction and receive rails from two directions. End posts are at the start and finish of a fence run and receive rails from one direction only. The calculator counts all posts together, and you can identify which type each post is during installation.
How far apart should gate posts be?
Gate posts should be spaced to match your gate width, typically 3 to 4 feet for a walk gate and 10 to 12 feet for a double drive gate. Gate posts are usually 6 by 6 and set in concrete because they carry the weight of the gate and experience more stress from opening and closing.