To fence 80 acres how many t-post and wire?

80 acres is 880 x 440 feet. Depends on how many cattle and how rough they are on your post settings. Most people around here in Oklahoma put their t-posts roughly 16' apart. This will take 164 posts. A roll of barbed wire will usually run a quarter of a mile of fence. So on a typical 5 wire fence it will take 30 rolls of barbed wire.