Fence posts are the backbone of any fence, and getting the count right matters for both your budget and your build. Order too few and you are back at the store mid-project. The count comes down to two things: the length of your fence and how far apart you set the posts.
Choose your post spacing
Most residential fences use posts spaced 6 or 8 feet apart, measured center to center. Which one you pick depends on the fence:
- 8 feet is the common default for wood privacy and picket fences, and it matches standard 8 foot rail lengths.
- 6 feet gives a stronger fence for tall privacy panels, heavy gates, or windy sites.
- 10 feet is sometimes used for wire and ranch fencing where the load is light.
Closer spacing means a sturdier fence and more posts. Wider spacing saves posts but can let rails sag over time. When in doubt, 8 feet is a safe standard for most yards.
The formula
The core formula is simple, and it hinges on one detail people forget: a straight run of fence always needs one more post than the number of sections.
Posts = (fence length ÷ spacing) + 1
For a straight 80 foot fence at 8 foot spacing: 80 divided by 8 is 10 sections, plus 1, which is 11 posts. If the length does not divide evenly, round the number of sections up before adding the end post.
Add posts for corners and gates
The basic formula covers a single straight line. Real fences turn corners and have gates, and each of those needs attention:
- Corners: every time the fence changes direction, that corner shares a post. If you calculate each straight run separately and add them, do not double count the shared corner post.
- Gates: a gate needs a sturdy post on each side. A gate in the middle of a run adds one extra post, since you now have a post on both sides of the opening. Wide or heavy gates often call for beefier posts set deeper.
- Ends: each free end of the fence gets its own post, which is the plus one in the formula.
For a simple rectangular yard, calculate the perimeter, divide by spacing, and add posts for each of the four corners. A gate replaces a section rather than adding much length.
How deep and how much concrete
Once you know the count, each post needs a hole. The rule of thumb is to bury one third of the post length, so a 6 foot tall fence uses an 8 or 9 foot post set about 2 to 3 feet deep. In cold climates, go below the frost line so the posts do not heave.
Most posts are set in concrete. A standard 6 foot fence post in a 10 inch hole takes about two 50 pound bags of fast-setting concrete per post. Multiply that by your post count to size the concrete order. Our fence post concrete calculator works this out per hole.
Let the calculator handle the layout
Our fence calculator takes your fence length and spacing and returns posts along with rails and pickets, so the whole material list comes out together. If you just want to compare spacings and see the post count, the fence post spacing calculator does exactly that. Plan the layout once, order the right count, and you will not be making a second trip halfway through the build.