Fence Post Calculator
Posts, H-braces, wire rolls and concrete for acreage and farm fencing.
1 acre = 43,560 sq ft.
Tighten on hills, curves and soft soil.
Spacing, roll lengths and concrete are typical figures (University of Missouri Extension, Red Brand, Stay-Tuff). Brace rule: 2 H-braces per corner, 1 per gate post and open end, plus an in-line brace on any straight pull over 650 ft. Check your wire maker and local conditions.
About the Fence Post Calculator
A square 2-acre field has about 1,181 ft of perimeter, so a barbed wire fence with posts every 12 ft needs roughly 104 posts: 92 line posts, 4 corner posts and 8 brace posts for the H-braces. Enter your land in acres (square or rectangular), as a total fence length in feet or meters, or as individual side lengths. Pick the fence type to load a typical post spacing, set the strands, gates and concrete option, and the calculator returns line, corner, gate and brace posts, H-brace assemblies, rolls of wire or panels, and 50 lb concrete bags for set posts.
How many fence posts do I need for 2 acres?
About 104 posts for a square 2-acre field fenced with barbed wire at 12 ft spacing. Here is where that number comes from:
- Area: 2 acres × 43,560 sq ft = 87,120 sq ft.
- Side: √87,120 ≈ 295.2 ft, so the perimeter is about 1,181 ft.
- Quick estimate: 1,181 ÷ 12 ≈ 99 post positions around the loop, 4 of them corners.
- With H-braces: each corner gets a brace in both directions, so 8 brace posts sit 8 ft out from the corners. The remaining 279 ft on each side needs 23 line posts at 12 ft or less.
- Total: 92 line + 4 corner + 8 brace = 104 posts, plus 2 more posts and 2 more braces for every gate.
Four strands of barbed wire on 1,181 ft is 4,722 ft of wire, or 4 rolls of 1,320 ft with a small allowance for wraps. These are the calculator's default inputs.
Acres to fence perimeter
The shape of the field matters more than most people expect. A square has the shortest perimeter for a given area; long, narrow fields need more fence and more posts.
| Acres | Square side | Square perimeter | 1:2 rectangle | 1:2 perimeter | 1:3 perimeter |
|---|---|---|---|---|---|
| 1 | 208.7 ft | 835 ft | 295.2 × 147.6 ft | 885 ft | 964 ft |
| 2 | 295.2 ft | 1,181 ft | 417.4 × 208.7 ft | 1,252 ft | 1,363 ft |
| 3 | 361.5 ft | 1,446 ft | 511.2 × 255.6 ft | 1,534 ft | 1,670 ft |
| 5 | 466.7 ft | 1,867 ft | 660.0 × 330.0 ft | 1,980 ft | 2,156 ft |
| 10 | 660.0 ft | 2,640 ft | 933.4 × 466.7 ft | 2,800 ft | 3,048 ft |
| 20 | 933.4 ft | 3,734 ft | 1,320.0 × 660.0 ft | 3,960 ft | 4,311 ft |
| 40 | 1,320.0 ft | 5,280 ft | 1,866.8 × 933.4 ft | 5,600 ft | 6,097 ft |
A square 40 acres is exactly a quarter mile on each side, so it takes one mile of fence.
Fence posts per acre by fence type
Total posts for a square field with no gates, using the typical spacing for each fence type and the brace rules below. Board and panel fences have no H-braces, just a post at every corner.
| Fence type (spacing) | 1 acre | 2 acres | 5 acres | 10 acres | 40 acres |
|---|---|---|---|---|---|
| Barbed wire (12 ft) | 76 | 104 | 160 | 228 | 448 |
| Woven / field fence (10 ft) | 88 | 120 | 192 | 268 | 532 |
| High-tensile smooth (25 ft) | 40 | 56 | 84 | 116 | 232 |
| Electric polywire (40 ft) | 24 | 32 | 48 | 68 | 132 |
| Board or 8 ft panels (8 ft) | 108 | 148 | 236 | 332 | 660 |
Typical post spacing, strands and roll sizes
| Fence type | Line post spacing | Typical strands | Roll or unit |
|---|---|---|---|
| Barbed wire | 8–12 ft (MU Extension allows 15–20 ft) | 4–5 | 1,320 ft (80 rods) |
| Woven / field fence | 10 ft or less | 1 row, often + 1–2 barbed | 330 ft (20 rods) |
| High-tensile smooth | 15–25 ft (wider with stays) | 5–8 | ~4,000 ft per 12.5-ga coil |
| Electric polywire / tape | 30–50 ft | 1–3 | 1,320 ft polywire |
| Wood board | 8 ft | 3–4 boards | 16 ft boards (2 bays) |
| Welded / privacy panel | Panel width (8 ft) | n/a | 1 panel per bay |
H-braces: how the calculator counts them
Wire fences are stretched tight, and the pull has to be held by braced assemblies, not line posts. The calculator uses these common rules:
- Corners: 2 H-braces per corner, one in each direction. Each adds a brace post 8 ft from the corner post.
- Gates: 1 H-brace on each gate post, so 2 per gate.
- Open ends: 1 H-brace at each end post of a straight run.
- Long runs: University of Missouri Extension recommends a braced line assembly every 650 ft when corners are farther apart than that. Some builders use 660 ft (40 rods). An in-line brace uses 2 posts.
Polywire, board and panel fences carry little or no tension, so the calculator counts corner and gate posts only.
Worked example: 10 acres of woven wire with 2 gates
A 10-acre field laid out as a 1:2 rectangle is 933.4 × 466.7 ft, with 2,800 ft of perimeter. Fence it with woven wire at 10 ft spacing and two 12 ft gates, one on each long side.
- Fence length: 2,800 − 24 ft of gates = 2,776 ft.
- Terminal posts: 4 corner posts + 4 gate posts.
- H-braces: 8 at corners + 4 at gates = 12, adding 12 brace posts. The gates split each long side into runs of about 461 ft, so no in-line brace is needed.
- Line posts: 266 at 10 ft or less.
- Total: 266 + 4 + 4 + 12 = 286 posts.
- Woven wire: 2,776 ft × 1.05 ÷ 330 = 9 rolls.
- Concrete: 20 corner, gate and brace posts × 2 bags = 40 bags of 50 lb.
Panel fences: posts = panels + 1
For privacy, welded wire or corral panels, the panel width sets the spacing. On one straight run, count the panels (fence length ÷ panel width, rounded up) and add one post. A 100 ft run of 8 ft panels needs 13 panels and 14 posts. Every separate run or corner adds a post, because each run starts and ends on its own post.
Concrete or driven posts?
Steel T-posts and many line posts are driven, not set in concrete. Farm corner and brace posts are often set with well-tamped soil instead, which drains better around wood posts. If you do use concrete, a typical 4 in post in an 8 to 10 in hole about 2 to 2.5 ft deep takes about 1.5 to 2 bags of 50 lb mix. Large 6 to 8 in brace posts in 12 in holes 3.5 to 4 ft deep take 4 bags or more, so raise the bags-per-post figure for those.
Sources and limits
All figures are typical estimates. Sources: University of Missouri Extension G1192, Constructing Wire Fences (line post spacing and braced line assemblies every 650 ft); Red Brand installation guides (barbed wire posts 8 to 12 ft, woven wire 10 ft or less); Stay-Tuff post spacing guide (8 to 25 ft depending on fence and terrain); NRCS electric and high-tensile fence specifications and Kencove installation guides (electric line posts 30 to 50 ft and more). Roll lengths are common retail sizes and vary by brand. Terrain, livestock pressure, soil and local codes can all call for closer spacing or extra braces.
How to use the Fence Post Calculator
- 01Choose how to enter the fence: acres with a field shape, a total fence length in feet or meters, or a list of side lengths.
- 02Pick the fence type. It loads a typical post spacing and strand count, which you can override for hills, curves or soft soil.
- 03Enter the number of gates and their width so gate posts and gate braces are counted and gate openings are removed from the wire.
- 04Choose whether corner, gate and brace posts (or every post) are set in concrete, then read total posts, H-braces, wire rolls and concrete bags.
Frequently asked questions
How many fence posts do I need for 1 acre?
A square acre is 208.7 ft on a side with 835 ft of perimeter. With barbed wire and posts every 12 ft that is about 76 posts: 64 line posts, 4 corner posts and 8 brace posts. Woven wire at 10 ft needs about 88, and high-tensile at 25 ft about 40.
How many fence posts do I need for 10 acres?
A square 10-acre field is 660 ft on a side, 2,640 ft around. Barbed wire at 12 ft spacing takes about 228 posts, including 16 brace posts, because each 660 ft side is just over the 650 ft pull where an in-line brace is recommended. A 1:2 rectangle has 2,800 ft of fence and needs more posts.
How many fence posts do I need for 100 ft?
For a straight 100 ft run with posts every 8 ft you need 14 posts (100 ÷ 8 = 12.5, round up to 13 bays, plus 1). A barbed wire run at 12 ft needs about 10: 2 end posts, 2 brace posts and 6 line posts.
How many fence posts per panel?
On a straight run you need one more post than panels: posts = panels + 1. Thirteen 8 ft panels cover 100 ft and need 14 posts. Each extra corner or separate run adds one more post.
How far apart should fence posts be?
Typical line post spacing is 8 to 12 ft for barbed wire, 10 ft or less for woven field fence, 15 to 25 ft for high-tensile wire, 30 to 50 ft for electric polywire, and 8 ft for board and panel fences. Space posts closer on hills, curves and soft ground.
How many bags of concrete per fence post?
About 1.5 to 2 bags of 50 lb concrete for a typical 4 in post in an 8 to 10 in hole about 2 to 2.5 ft deep. Large corner and brace posts in 12 in holes 3.5 to 4 ft deep can take 4 or more bags. Driven T-posts need none.