Figure out exactly how much fence wire you need, how many posts to buy, and what it will cost. Enter your field dimensions or total perimeter, pick your fence type, and this calculator handles the math — wire in feet and rolls, line posts, corner posts, gate posts, staples, and a material cost estimate.
The math behind a fence wire estimate is straightforward once you know your perimeter and fence type. Start with total perimeter, subtract your gate openings (gates don't need wire), then multiply by the number of strands for wire fence types. For a 5-acre square pasture — roughly 1,470 linear feet per side — your perimeter is 5,880 feet. Three strands of barbed wire means 17,640 feet of wire total, or 14 rolls of standard 1,320-foot barbed wire. Field fence (woven) is different: you buy it by the roll at the full height, so you only need footage equal to the perimeter, not multiplied by strands.
The roll sizes matter. Barbed wire comes in 1,320-foot rolls (quarter-mile), which is the standard for most cattle and pasture fencing. Field fence rolls are shorter — typically 330 feet — because the woven product is heavier and harder to handle. High tensile smooth wire comes in long 4,000-foot rolls specifically because it is installed under very high tension and needs fewer splices over long runs. Electric polywire typically comes on 1,320-foot spools. When you calculate rolls to buy, always round up to the next full roll; you cannot buy partial rolls from most suppliers.
For irregular-shaped properties, walk your boundary with a measuring wheel or use GPS mapping software to get the actual perimeter. Google Earth Pro has a built-in path measurement tool that works well for fence planning. Add 5–10% to your final wire order to account for waste, splice overlaps, tension adjustments, and the occasional broken strand during installation.
Post spacing is the single biggest variable that affects both cost and fence performance. The closer your posts, the stronger your fence — but the more materials and labor required. Recommended spacing depends on your fence type and livestock:
Corner posts are the most critical structural component of any wire fence. Every strand of wire pulls against the corner post continuously, and in a 5-acre pasture with three strands of barbed wire, that's roughly 600–900 lbs of constant horizontal load on each corner. A single wooden post will eventually pull over under that load, which is why proper corner construction matters.
The standard corner assembly for most fence types is an H-brace: two vertical posts set 6–8 feet apart, connected by a horizontal wooden brace at the top, with a diagonal wire running from the top of the end post down to the bottom of the line post, twisted tight. This H-brace assembly distributes the wire tension load down into the ground rather than pulling the post over. For barbed wire and standard woven field fence, one H-brace per corner is usually sufficient. For high tensile wire under full tension, a double H-brace (four posts and two horizontal braces) at each corner is recommended for long fence runs. Gate posts also need H-brace assemblies because of the constant swinging and weight of the gate.
When this calculator shows "corner posts," it shows the primary corner post count. Add 1–2 additional posts per corner if you're building proper H-brace assemblies for high tension wire or woven field fence on large pastures. For barbed wire on typical cattle operations, the single-post corner with good tamping and the right post diameter (at least 5" for wood, 8-foot heavy T-post for metal) often works fine.
For most cattle and pasture applications, 10–12 feet is standard line post spacing. Horse fences should be no wider than 8 feet. High tensile wire can span 14–20 feet. For goats and hogs, use 6–8 foot spacing and consider a bottom wire close to the ground. The 10-foot spacing used as the default in this calculator is the most common choice for general-purpose livestock fencing because it balances material cost with fence rigidity.
A mile of fence is 5,280 linear feet. With 3 strands of barbed wire, you need 15,840 feet of wire. At 1,320 feet per standard roll, that's exactly 12 rolls per mile for 3 strands — or 4 rolls per strand per mile. Add 10% waste and round up. For 4-strand barbed wire on a full mile, you need 17 rolls (16 exact plus 10% buffer). Posts: at 10-foot spacing, 1 mile requires approximately 529 posts plus 4 corner posts and your gate posts.
Barbed wire is smooth or twisted wire with evenly-spaced barbs. It deters animals through discomfort rather than physical barrier — most livestock will challenge it and can push through if motivated. It's cheap, fast to install, and sufficient for beef cattle and horses (with enough strands). Field fence (woven wire, also called stock fence or page wire) is a woven grid of horizontal and vertical smooth wires. The horizontal wires are spaced closer together near the bottom to prevent small animals from ducking under, and wider near the top where pressure is less. It creates a true physical barrier for sheep, goats, hogs, and small livestock that barbed wire cannot contain. Field fence is more expensive per roll but handles a wider variety of animals. Many operations combine woven field fence for the lower portion with one or two strands of barbed wire along the top to deter adult cattle from leaning.
Yes, for any permanent fence with wire under tension. A corner post without a brace assembly will be pulled to a lean within a season by the constant wire tension. The H-brace is not optional for barbed wire, field fence, or high tensile installations — it is a fundamental part of the fence structure. For temporary electric fencing, braced corner posts are less critical because the wire tension is low, but they still extend fence life significantly. Budget the lumber, lag screws or staples, and brace wire into your materials list. A proper H-brace uses two posts set 6–8 feet apart, a 4" or larger horizontal wood brace, and a diagonal wire with a twitch stick to pre-load tension against the fence pull direction. Each corner and each gate post location needs this assembly for a fence that will last 20–30 years.