Fence Calculator

The calculator divides your total fence length by the post spacing and rounds up to get the number of spans. For an open run, it adds one post for the far end. For a closed loop, the span count equals the post count because the path closes back on itself. Each gate adds two posts to hold the gate hardware, regardless of run type.

An open run has two free ends, like a fence along one side of a yard. A closed loop wraps a full perimeter and meets itself, so the last span shares the starting post. The calculator uses one fewer post for a closed loop. For a 200 ft perimeter at 8 ft spacing, an open run needs 26 posts while a closed loop needs 25.

The calculator subtracts 4 ft per gate from the total fence length to get the picketed run, converts that to inches, and divides by the picket pitch (picket width plus gap), rounding up. For a 200 ft fence with no gates, 5.5 in pickets, and a 0.25 in gap: 2,400 in / 5.75 in = 418 pickets.

Two rails works for most residential 4 ft and 6 ft fences. Use three rails for fences 8 ft or taller, high-wind locations, or anywhere the fence needs to resist lateral pressure from livestock or soil. Three rails also reduce the chance of pickets warping or bowing over time.

The calculator counts one 50 lb bag of concrete per post, which is a common residential estimate for a small to mid-size hole. Gate posts, corner posts, and end posts carry more load, so plan on two bags at those locations. Check with your local building department if you are in a high-wind or frost-prone area, since minimum hole depth and concrete needs vary.