How much fence one acre takes
An acre is 43,560 square feet. Fenced as a square, each side is the square root of that, 208.7 ft, and the fence around it is four times the side: 835 ft, or 0.16 miles. That is the least fence that can hold one acre, because a square has the shortest boundary of any four sided field.
Square perimeter = 4 × √(acres × 43,560 sq ft)
Most one acre lots are not square. The shape changes the answer more than people expect:
| Shape of 1 acre | Sides | Fence around it |
|---|---|---|
| Square | 208.7 × 208.7 ft | 835 ft |
| 2:1 rectangle | 295.2 × 147.6 ft | 886 ft |
| 4:1 strip | 417.4 × 104.4 ft | 1,044 ft |
The 2:1 field needs 51 ft more fence than the square, about 6% extra. A long 4:1 strip, the kind you get behind a house on a narrow lot, needs 209 ft more, a quarter more wire and posts for the same grass. If your acre is an odd shape, draw it on the map in the calculator above rather than guessing from the acreage.
A worked example: barbed wire around a square acre
For four strands of barbed wire with steel T-posts every 12 ft and one 12 ft drive gate, the calculator counts:
- 823 ft of fence once the gate is cut out
- 74 T-posts, including 10% extra
- 22 wood posts: 4 corners, 2 gate posts and 16 brace posts
- 3 rolls of barbed wire (1,320 ft each) for 3,621 ft of strand
- $1,180 to $5,540 installed
Shape matters for the bracing too. The University of Kentucky's rule is a single H-brace for a run up to 165 ft and a double H-brace beyond that. Every side of the square acre is 208.7 ft, so every corner gets a double brace. The short sides of the 2:1 field are only 147.6 ft, so they get single braces, and the rectangle needs 18 wood posts instead of 22 even though its fence is longer. Switch the table above to the 2:1 rectangle to see both.
Fencing one acre for horses
If the acre is a horse paddock, this is where the table's cheapest options stop being right. NRCS California advises considering avoiding barbed wire and steel T-posts for horses. Penn State Extension sets horse fence at 54 to 60 in, with the top at wither height, the bottom about 8 in off the ground, and gaps of 12 in or less between rails or strands (18 in for electric). It also sets line posts 36 in deep and corner and gate posts about 48 in deep. For horses, look at the electric row as a hot wire on the inside of a wood or mesh fence, not as barbed wire on T-posts. Penn State puts horse and handler gates at 4 ft minimum, 5 ft preferred.
Fencing one acre for goats or sheep
Sheep and goats need wires close to the ground, so the 2 wire electric row is too thin for them. NRCS Iowa's minimum for a sheep and goat cross fence is 3 electric wires at 8, 20 and 32 in, and its predator resistant perimeter uses 8 wires starting 4 in off the ground. The woven row in the table assumes 47 in fence on 14 ft T-post spacing with one barbed strand on top, which takes 3 rolls of 330 ft woven wire plus 1 roll of barbed wire for the square acre.
What does it cost to fence one acre?
Our installed range comes from per foot prices in HomeAdvisor's and Fixr's cost guides. It lines up with HomeAdvisor's own per acre figure of $630 to $5,900 for livestock fence, with an average of $1,700. High tensile has the narrowest range at $1,140 to $2,660, because its posts sit 25 ft apart and two 4,000 ft rolls cover all five strands.
Growing past one acre? The 2 acre page shows where roll sizes start to matter, the farm fence calculator covers livestock fence in general, and the fence calculator covers every other style.