Fence Post Calculator
This fence post calculator returns the number of fence posts you need based on total length, post spacing, and gate count. Enter your run length below to get line posts, corner posts, and gate posts broken out separately.
4x4 posts (3.5" actual), 2 ft bury depth.
A fence post calculator answers how many fence posts do I need before you dig a single hole. The number of fence posts depends on total length and post spacing only — not on fence style — but a real order also needs to separate line posts, corner or end posts, and gate posts, since each plays a different structural role. This tool feeds the same post math used across every fence calculator on this site, including the style-specific wood fence calculator.
Line Posts vs Corner, End, and Gate Posts
A line post sits along a straight run and carries rails on both sides — these make up most of a fence's post count and use the formula sections + 1. A corner post sits where two runs meet at an angle and carries rails from two directions, so it takes more load than a line post and should always be set at least as large as your gate posts. An end post caps a run where it stops, similar to a corner but with rails on one side only. A gate post flanks a gate opening and carries the full swing weight and impact of daily use, which is why professionals recommend 6×6 gate posts even on a fence built entirely from 4×4 line posts.
How the Fence Post Calculator Works
- Subtract gate width from total length to get the fence length that needs line posts.
- Divide by post spacing and round up for the number of sections.
- Add 1 to the section count for line posts — a fence needs one more post than it has sections.
- Add 2 posts per gate opening for gate posts, since each side of a gate needs its own post.
- Total posts = line posts + gate posts, plus one extra post at each corner beyond the first in an enclosed layout.
Worked example — 100 feet, 8-ft spacing, one 4-ft gate: 100 − 4 = 96 feet of fence line, or 96 ÷ 8 = 12 sections. Line posts = 12 + 1 = 13, gate posts = 2 × 1 = 2, for 15 posts total.
Fence Post Count Chart by Spacing
Line posts needed for a straight run at three common spacing widths, no gates.
| 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 |
Tighter 6-ft spacing is used for taller fences, high-wind areas, and heavier panel materials; wider 10-ft spacing is standard for chain link. The fence post spacing calculator shows the equal spacing that keeps every section the same width when your total length doesn't divide evenly.
4×4 vs 6×6 Posts
A 4×4 post (3.5 inches actual) is the standard line post for wood fences up to 6 feet tall. Step up to a 6×6 post (5.5 inches actual) for any gate post, any corner post carrying two directions of rail, and every post on a fence over 6 feet tall, since the added height puts more leverage on each post in wind. Vinyl fences use a 5×5 post (5.0 inches actual) instead of dimensional lumber.
Post Length and Depth Rule
Post length follows a simple formula: bury at least a third of the total post height, with a 2-ft minimum, then round the buried depth up to the nearest half foot. A 6-ft-tall fence needs a 2-ft bury (6 ÷ 3 = 2), for an 8-ft post overall; an 8-ft-tall fence needs a 3-ft bury (8 ÷ 3 = 2.67, rounded up to 3), for a 12-ft post.
| Fence height | Bury depth | Post length (stock) |
|---|---|---|
| 4 ft | 2 ft | 8 ft |
| 5 ft | 2 ft | 8 ft |
| 6 ft | 2 ft | 8 ft |
| 7 ft | 2.5 ft | 10 ft |
| 8 ft | 3 ft | 12 ft |
Cold climates need a deeper bury than the height-based minimum if the local frost line runs deeper — check the fence post depth and frost line guide before you cut posts to length.
Posts for an Enclosed Perimeter
Fencing a full property perimeter instead of a single straight run changes the post count slightly: an enclosed rectangle shares its starting and ending post, so total posts equal total sections rather than sections plus one. Add a corner post at each of the four corners of a rectangular lot, sized the same as a gate post since corners carry rails from two directions. Measure each side separately if the lot isn't a true rectangle, then sum the sections before adding corner and gate posts.
Post Depth and Concrete
Once you know your post count and depth, the concrete per fence post calculator sizes the hole and bag count for each post size — typically a 10-inch hole for a 4×4 and a 12-inch hole for a 6×6. Call 811 before digging any hole so utility lines get marked first.
Waste and Ordering
Posts don't carry a waste factor the way pickets and rails do, since you're not cutting them to a non-standard length — order exactly the number the calculator returns, plus one or two spares for a post that arrives split or warped. Buy gate posts and corner posts as a separate line item from line posts if your supplier stocks 6×6 separately from 4×4.
Next Steps
Once you have an exact post count, the fence cost calculator turns that number into an installed cost range including material and labor for setting posts.