How much fence five acres take
Five acres are 217,800 square feet. As a square, each side is 466.7 ft and the fence around it is 1,867 ft, about 0.35 miles. Stretch the same area into a 2:1 rectangle and the sides come out at a round 660 by 330 ft, with 1,980 ft of fence: 113 ft more, or 6%.
Square side = √(acres × 43,560); rectangle width = √(acres × 43,560 ÷ 2), length = 2 × width
The 660 by 330 ft layout is worth knowing because 660 ft is the University of Kentucky's limit for a run held by double H-braces at each end. Beyond 660 ft it adds a braced pull post. A five acre field laid out 660 by 330 needs no pull posts, and neither does the square. Both need 26 wood posts with one 12 ft gate: 4 corners, 2 gate posts and 20 brace posts.
Worked example: five acres of electric fence
Electric fence changes the post count more than any other choice, because its line posts can sit far apart. Around the square with 2 hot wires, posts every 40 ft and a 12 ft gate:
- 1,855 ft of fence after the gate
- 48 T-posts with 10% extra, against 165 for barbed wire at 12 ft
- 26 wood posts, the same as any other wire fence here
- 3,710 ft of wire, 0.70 miles, which is 4,080 ft or 4 rolls of 1,320 ft with the waste allowance
- $2,010 to $11,730 installed
The Iowa Beef Center's guide to permanent electric fence says high tensile electric posts can be "up to 120 feet apart for a single wire", but that "40 - 60 feet spacing is more realistic". At 60 ft the same fence needs 30 T-posts instead of 48. Its wire heights for cows and calves are 1 wire at 28 to 34 in, or 2 wires at 22 and 32 in with posts 40 to 60 ft apart. For sheep, goats or mixed stock it moves to 3 or 4 wires and posts 20 to 40 ft apart, so change the hot wires and spacing in the calculator below to match.
What size energizer for five acres?
NRCS Iowa sizes a fence charger at one joule for each mile of wire, counting every strand. Two wires around the square five acres are 0.70 miles of wire, so a 1 joule energizer covers it. Three wires would be 5,565 ft, just over a mile. The University of Georgia adds 25% to the rating where weeds and grass touch the wire.
NRCS Iowa sets minimum shock at 1,000 V for cattle and horses and 2,000 V for sheep, and 2,500 to 3,000 V for goats. Grounding follows the charger: NRCS Iowa calls for 3 ft of ground rod per joule with rods at least 10 ft apart, and the University of Georgia for at least 24 ft of rod, as three 8 ft rods 6 ft apart.
Comparing the five fences
On the square five acres the table shows a wide spread. Barbed wire needs 165 T-posts and 7 or 8 rolls depending on strand count. Woven wire needs 145 T-posts, 7 rolls of 330 ft mesh and 2 rolls of barbed wire for the top strand, and has the highest low end at $2,930. High tensile at 25 ft needs 80 T-posts and 3 rolls of 4,000 ft wire, and its installed range, $2,380 to $5,240, has the lowest top end. HomeAdvisor's per acre figure of $630 to $5,900 for livestock fence, times five, is $3,150 to $29,500. Our ranges start lower because they are priced by the foot, and fence grows more slowly than area: five acres take 2.2 times the fence of one acre, not five times.
Go smaller with the 2 acre page or larger with the 10 acre page. The electric fence calculator works through an electric fence on its own, and the farm fence calculator covers livestock fence in general.