How many fence posts do I need?
Split the fence into straight stretches between corners, ends and gates. Each stretch is divided into equal sections no longer than your post spacing, and each section needs a post at its far end. Corners are shared by the two stretches that meet there, and every gate gets a post on each side.
Sections per stretch = stretch length ÷ spacing, rounded up · Posts on one straight run = sections + 1
For a fence that closes on itself, such as a square paddock, the last section ends at the first post, so the post count equals the section count.
A worked example
The calculator opens on 150 ft of wood privacy fence with two corners, a 4 ft walk gate and 8 ft maximum spacing:
- Two corners split 150 ft into three 50 ft sides.
- The gate goes in one side and leaves two 23 ft pieces. Each needs 3 sections (23 ÷ 8 = 2.9, rounded up), with 2 line posts between them.
- Each plain 50 ft side needs 7 sections (50 ÷ 8 = 6.25, rounded up) and 6 line posts.
- Line posts: 2 + 2 + 6 + 6 = 16. Add 2 corner posts, 2 end posts and 2 gate posts for 22 posts.
At 6 ft spacing the same fence takes 28 posts; at 10 ft, 18.
For a 6 ft fence, the calculator also gives the post length: 10 ft line posts in 42 in holes, and 10 ft corner, end and gate posts in 54 in holes. Those depths come from the fence post depth calculator: half the height above ground plus 6 in of gravel, and 12 in more for posts that carry a gate or the pull of a run.
Posts needed by fence length
Straight runs with no corners or gates, from the calculator:
| Fence length | 6 ft spacing | 8 ft spacing | 10 ft spacing |
|---|---|---|---|
| 50 ft | 10 | 8 | 6 |
| 100 ft | 18 | 14 | 11 |
| 150 ft | 26 | 20 | 16 |
| 200 ft | 35 | 26 | 21 |
| 300 ft | 51 | 39 | 31 |
| 1 mile (5,280 ft) | 881 | 661 | 529 |
| 1 acre, square (835 ft around) | 140 | 108 | 84 |
Each corner you add can add a post, because a corner splits one stretch into two and each is rounded up on its own. Gates add two posts each but take their width out of the fence.
Which spacing should I use?
The fence type menu fills in the spacing the rest of this site uses. Wood privacy and picket fences use 8 ft, the standard Family Handyman gives for wood, composite and solid vinyl. Vinyl and aluminum follow their panels, 6 or 8 ft. Chain link line posts are set no more than 10 ft apart, per the Chain Link Fence Manufacturers Institute. Farm fences spread out much further: University of Tennessee Extension lists 12 to 14 ft for barbed wire, 14 to 16 ft for woven wire, and 40 ft or more for high tensile and electric fence. The fence post spacing calculator shows how to space a single run evenly.
Line, corner, end and gate posts
The count splits posts by job because they are not the same post:
- Line posts hold the rails, panels or wire along a stretch.
- Corner and end posts take the strain where the fence turns or stops. Penn State Extension sets them deeper than line posts; the calculator adds 12 in.
- Gate posts carry the gate. Chain link calls corner, end and gate posts terminal posts, and the CLFMI product manual says they are generally one size larger than line posts.
- On wire fences, University of Tennessee Extension asks for corner and gate posts at least 8 in across, and the line posts are often steel T-posts.
What length of post should I buy?
Quikrete's rule puts a third of the post in the ground, so the post is 1.5 times the fence height. The gravel under it adds to the hole, not to the post. A 4 ft fence takes 6 ft posts, a 6 ft fence 10 ft posts (9 ft needed, rounded up to stock), and an 8 ft fence 12 ft posts. Corner and gate posts may need the next length up.
What to work out next
Turn the post count into bags with the fence post concrete calculator, or get the posts together with rails, boards or panels from the fence calculator.