What the fence estimate page focuses on
Omni's fence estimate page is about material planning rather than pricing. It outputs the number of posts, sections, rails, pickets, and the concrete needed for the post footings so you can prepare a shopping list before building.
Source formulas used in this version
Number of posts = Fence length / Post spacing + 1
Post length = 1.5 x Fence height
Number of rails = Rails per section x Number of sections
Number of pickets = Fence length / (Picket width + Picket spacing)
Concrete volume = Hole volume - Buried post volume
Example highlighted in Omni's FAQ
The source FAQ shows a 300 ft fence with 7 ft post spacing. That gives about 44 posts after rounding up. It also walks through a 4 x 4 post in a 6 ft fence, where the concrete volume for one footing comes out to 4,608 in^3.