CALCULATION METHOD
How much fencing do I need?
Subtract gate openings from the total fence length. For preassembled fencing, divide the remaining length by panel width and round up. For a component-built wood fence, divide the length in inches by picket width plus gap, then calculate sections from the maximum post spacing.
Net fence length = total length − gate openings
Panels = net length ÷ panel width, rounded up
Pickets = net length ÷ (picket width + gap), rounded up
Posts = sections + open fence runs + gates
Rails = sections × rails per section
120 ft fence calculator example
A 120 ft open fence with one 4 ft gate leaves 116 ft of panel coverage. With 8 ft panels, round 14.5 up to 15 panels. Add one ending post for the open run and one gate post to the 15 section posts for an estimate of 17 posts.
Fence panel and post calculator
Common preassembled panels are 6 or 8 ft wide, but use the actual product dimension and its installation instructions. Panel attachment style, brackets, slopes, and corners can change center-to-center post spacing. Never lay out all holes from a nominal label alone.
Fence picket and rail calculator
Individual-board mode combines the visible picket width and desired gap. It also estimates horizontal rails from the selected post spacing and rails per section. Closed privacy fences use a zero gap; board-on-board or alternating layouts require a project-specific takeoff rather than this single-layer formula.
Concrete for fence posts
The optional footing estimate treats each hole as a cylinder, subtracts the square post and gravel depth, then divides the remaining volume by bag yield. Actual footing size depends on the fence, soil, frost line, wind exposure, and local requirements. The Home Depot guide recommends checking utilities, digging below frost depth where applicable, and following local requirements.
Lowe’s / Outdoor Essentials fence estimator for panel and post formulas; The Home Depot fence-building guide for picket calculations, typical 6–8 ft post spacing, gates, holes, gravel, frost depth, and utility precautions. Accessed September 11, 2026.