Barbed Wire Fence Calculator

Barbed Wire Fence Calculator works from a fence line, a field's sides or its acreage to give the wire length, rolls, weight by wire size, posts, staples and the full material cost.

Barbed Wire Fence Calculator Modes

The Barbed Wire Fence Calculator starts from whatever you know about the job. You can enter a fence line from end post to end post, the length and width of a rectangular field, or the field area in acres or hectares with a length-to-width ratio. The last two modes put a braced post at all four corners.

From there it works out the total wire length with an allowance for wraps and splices, and the rolls to buy at your roll length. It also gives the wire weight for your wire size, the line, corner, gate and pull posts, the H-brace posts and rails, the clips or staples, and the material cost at your own prices. Gate openings come off the wired length, since no wire crosses a gate.

Take the default 660 ft fence line with 4 strands, posts every 10 ft and one 12 ft gate. The wired line is 648 ft, so you need 2,851 ft of wire with 10% extra. That is 3 rolls of 1,320 ft with 1,109 ft left over, weighing about 172 lb in 12.5 ga wire.

The line itself takes 67 posts: 63 line posts, 2 end posts and 2 gate posts. Each end and gate post gets an H-brace, which adds 4 brace posts and 4 rails, for 71 posts in all. The 63 line posts take 252 clips or staples, one per strand on each post.

Barbed Wire Formula for a Fence

Start with the wired length. Take the gate openings out of the fence line, where P is the fence line, g is the number of gates and w_g is the width of each gate.

$$L_w=P-g\times w_g$$

Multiply the wired length by the number of strands n, then add your extra allowance e for wraps at the braces, ties and splices. Most estimates use 5% to 10%.

$$W=L_w\times n\times (1+e)$$

Divide the wire length by the roll length R and round up to get whole rolls. Rolls in the US are usually 1,320 ft, which is a quarter mile or about 402 m.

$$N_r=\lceil \frac{W}{R}\rceil$$

For a straight line, posts equal the wired length divided by the post spacing d, rounded up, plus one for the far end. Each gate adds one more post, since the gate splits the run and no post stands in the opening.

$$N_p=\lceil \frac{L_w}{d}\rceil +1+g$$

A rectangular field counts each side the same way without the extra post, since the corners are shared. Braces come on top. The tool sets 2 H-braces at each corner, 1 at each end or gate post and 2 at each pull post, and every brace adds one brace post and one rail.

How Much Barbed Wire to Fence 1 Acre

One acre is 43,560 sq ft. Fenced as a square, each side is 208.7 ft and the fence line is about 835 ft. A 2:1 rectangle of the same acre needs 886 ft of fence, and a long 4:1 strip needs 1,044 ft, so the field shape matters as much as its size.

The table uses square fields, posts every 10 ft, 10% extra and 1,320 ft rolls. Enter your own field in rectangle or area mode to get exact figures.

So one 1,320 ft roll runs a single strand about one and a half times around a square acre. A 4-strand fence on 1 acre takes 3 rolls, and the same fence on 20 acres takes 13 rolls and 392 posts, counting the 8 corner brace posts. The Rectangle Fence Perimeter Calculator gives the fence line for any other field shape.

The post count for 1 acre drops as the spacing opens up. A square acre takes 84 posts at 10 ft, 72 at 12 ft and 56 at 16 ft. The two H-braces at each corner add 8 brace posts in every case, so the tool shows 92, 80 and 64.

Fence Posts for 100 ft and 200 ft of Fence

A straight run needs one post more than the number of spaces. For 100 ft of fence at 10 ft spacing, that is 10 spaces and 11 posts. For 200 ft, it is 21 posts. The table counts posts in the line only; an H-brace at each end adds 2 brace posts, so the tool shows 13 and 23.

The USDA NRCS Ohio standard for barbed wire fence caps line post spacing at 16 ft. It sets wood line posts 34 in deep and steel T-posts 21 in deep. The tool warns when you space posts wider than that 16 ft limit.

Braces carry the wire tension, so plan them before you count line posts. The NRCS standard calls for a corner brace wherever the fence turns more than 15 degrees and a pull assembly at least every 660 ft on standard barbed wire. The Max Run Between Pull Braces field defaults to 660 ft, so a 1-mile straight line gets 7 pull posts. High-tensile wire needs no pulls, and the field hides when you pick it. The Fence Post Depth Calculator sets hole depth and concrete for each post.

Barbed Wire Weight and Length per Kg

Wire weight depends on the wire size and how closely the barbs are spaced. The Barbed Wire Fence Calculator defaults to US 12.5 ga 4-point wire, gives the weight for whichever size you pick, and lists how far 1 kg and 50 kg of each size will reach.

Bekaert lists its 15.5 ga high-tensile barbed wire at 41.5 lb per 1,320 ft roll, which works out to about 47 g/m. A 12.5 ga roll of the same length weighs about 80 lb, so it carries roughly twice the steel. The IS 278 masses come from the Indian standard's own size table for barbed wire.

So 1 kg of barbed wire covers anywhere from 20 ft for heavy 12 x 12 gauge to 70 ft for 15.5 ga high-tensile. A 50 kg lot of IS 278 Size 1 runs about 344 m, or 1,127 ft. Where wire is sold by weight, multiply the kilograms by the meters per kilogram to get the length.

Barbed Wire Fence Cost

Fence cost is wire plus posts plus labor. In the Barbed Wire Fence Calculator you can price wire per roll, per kilogram, per pound, or per meter or foot, and pick US dollars, Indian rupees, euros or pounds. Corner and gate posts take their own price, because braced posts cost far more than line posts.

With the tool's sample prices of 95 dollars a roll, 5 dollars per line post and 25 per braced or brace post, 200 ft of 4-strand fence comes to about 290 dollars. That covers 1 roll, 19 line posts, 2 end posts and 2 H-brace posts, or 1.45 dollars per foot before labor. Brace rails and brace wire are listed but not priced, so add them from your supplier's quote.

To price 100 m of barbed wire, work out the weight first. One strand of 100 m weighs about 9 kg in 12.5 ga wire and about 14.6 kg in IS 278 Size 1. A 4-strand fence with 10% extra needs 440 m of wire, which is 40 kg to 64 kg, and that weight times your price per kg is the wire cost.

The cost per foot or per meter result lets you scale the price up to a whole field. The Print Results button saves the full material list as a PDF estimate, and Copy Results pastes it into a spreadsheet.

Barbed Wire Strands for Cattle, Horses and Sheep

That NRCS standard sets 5 strands for a standard barbed wire fence, with the top wire 48 in above the ground. It allows 3 or 4 strands for interior and exclusion fences. The same standard says barbed wire fence is not for horses, sheep, swine or goats. 48 in 39 in 30 in 21 in 12 in NRCS 5-strand spacing above the ground line

For cattle, 4 or 5 strands is the usual choice. Ask Extension's barbed wire strand spacing guide gives common layouts for 3 to 6 strands and line posts 12 to 20 ft apart.

Horses can tear their legs and hides on barbs, so smooth high-tensile wire, board or mesh fences suit them better. For a horse pen, the Round Pen Calculator sizes panels and gates. Sheep and goats push through gaps between strands, and woven wire stops them; the Fence Calculator handles posts, rails and panels for other fence types.