The diagram below can be used to calculate the number of rods required to enclose fields of various sizes. These are suggested guidelines using the square area to be fenced.  http://www.redbrand.com/FenceBasics/AcreageGuideAndTable.aspx

 

Acreage Guide

1 rod = 16 1/2 ft.
10 rods = 165 ft.
20 rods = 330 ft.
1/4 mile = 1,320 ft. or 80 rods
1/2 mile = 2,640 ft. or 160 rods
1 mile = 5,280 ft. or 320 rods

The table below helps calculate the number of rolls of fence required to enclose various acreage sizes. These are suggested guidelines assuming the square area to be fenced.

Acres Fence
330 ft.
Rolls		 Fence
100 ft.
Rolls		 Barb Wire
1320 ft.
Rolls
1 Strand		 Acres Fence
330 ft.
Rolls		 Fence
100 ft.
Rolls		 Barb Wire
1320 ft.
Rolls
1 Strand
1 3 9 1 65 21 68 6
2 4 12 1 70 22 70 6
3 5 15 1 75 22 75 6
4 5 17 2 80 23 75 6
5 6 19 2 85 24 77 6
6 7 21 2 90 24 80 6
7 7 22 2 95 25 82 7
8 8 24 2 100 26 84 7
9 8 25 2 105 26 86 7
10 8 26 2 110 27 88 7
11 8 28 2 115 28 90 7
12 9 29 3 120 28 92 7
13 10 31 3 125 28 94 7
14 10 31 3 150 31 103 8
15 10 33 3 175 34 111 8
16 11 34 3 200 36 118 9
17 11 35 3 225 38 126 10
18 11 36 3 250 40 132 10
19 11 37 3 275 42 139 11
20 12 38 3 300 44 145 11
25 13 42 4 325 46 151 12
30 14 46 4 350 48 157 12
35 15 50 4 375 49 162 13
40 16 53 4 400 51 167 13
45 17 56 5 425 53 173 13
50 18 60 5 450 54 177 14
55 19 62 5 475 56 182 14
60 20 65 5