Development, not height
Flatten the mesh out and it is one strip. On the default settings that strip is 24 inches above grade, 10 inches straight down, 12 inches turned outward at the bottom and nothing at the top: 46 inches. Nobody sells 46 inch mesh. A 36 inch roll needs two courses lapped 4 inches, which covers 68 inches, so 22 inches gets trimmed off — 30.6% of every foot of mesh bought, along the entire line.
A 48 inch roll would cover the same 46 inches in one course with 2 inches trimmed, which is about 4%. Same barrier, same job, and the difference is what roll got ordered. That is the one number on this page worth playing with before anything is bought.
The arithmetic reconciles
Two courses of 36 inches is 72 inches of mesh bought. It goes three places and only three: 46 inches of development, 4 inches into the lap between the courses, 22 inches into the bin. 46 + 4 + 22 = 72. If those three do not add to the height bought, something in the input is wrong.
Along the line as well as up it
The default 194 feet of line off 100 foot rolls with a 6 inch end lap takes two rolls per course: the first covers 100 feet, the second covers 99.5 more, and 199.5 clears 194. One roll would not. Two courses of that is four rolls, plus 3.99 cubic yards of trench out of the ground — 4.99 once it has swelled 25% — and 97 pins along the apron.
Related pages
For an enclosed run with walls, a roof and a skirt rather than a single line, the poultry run mesh calculator does the area version of this. For the posts, the fence post calculator handles spacing and concrete and the chain link material page covers rail and fittings. For a trench dug for a different reason, the barn water line trench page and the drain tile trench calculator use the same volume arithmetic.
Questions people ask
How deep should the buried leg be?
That is not a figure this page will supply, and it should not come from a calculator at all. It depends on soil, on the site, and on what the barrier is for, and the sources worth asking are your state extension service, the local conservation office or whoever is doing the work. The field exists so their number drives the take-off.
Does the apron have to be buried?
The page does not care either way and the mesh cost is the same, because the apron uses the same width of material whether it goes under the soil or lies on the surface under pins. What changes is the trench: a surface apron means the trench only has to take the vertical leg, and the pin count becomes the fastener line rather than a nicety. Both are covered above.
Why does the roll height matter more than the roll length?
Because whatever is trimmed off the height is trimmed along every foot of the line, while the length only affects how many joins there are. On the defaults the height mismatch throws away 30.6% of the mesh. No amount of care with the end laps recovers a fraction of that.
Should I add a course or buy a taller roll?
Compare them in this page and the answer is usually obvious. A second course adds the lap, the trimmed excess, and a line of ties along the whole run that somebody has to fit. A taller roll costs more per foot but often less per job. What tips it the other way is when the taller roll is not stocked, which is a supplier question rather than an arithmetic one.
Will this keep animals out?
The page makes no claim of that kind and will not. It is a materials take-off: it converts the dimensions you supply into mesh, courses, rolls, spoil and pins, and it publishes no mesh size, no depth and no view about what any animal can pass or dig under. Those figures come from your state extension service or your supplier. Anything involving an animal already present, or a protected species, belongs with your state wildlife agency and a licensed wildlife control operator.