Fence Calculator

How to use the fence calculator

1. Enter the length of each side in feet. Side 1 is required; add sides 2 to 4 for an L, U or full enclosure. Tick Closed loop if the last side returns to the first post (needs at least three sides).
2. Set the post spacing (8 ft is common; match it to your panel width for prefab panels) and the height above ground.
3. Enter the number of gates and their width.
4. Choose the style: privacy boards touching, picket with a gap, or panel. For boards, enter rails per section, board width and, for pickets, the gap.
5. Enter the actual post width: a nominal 4×4 measures 3.5 in.
6. Pick the concrete bag. In Advanced options you can set the hole diameter, depth and gravel base yourself.
7. Add unit prices if you want a total cost.

How the calculator works

• Fence length = sum of the sides − gates × gate width
• Sections = each side ÷ post spacing, rounded up, then added
• Posts = sections + 1 + one per gate (− 1 for a closed loop)
• Rails = sections × rails per section; the gate opening is not subtracted, which keeps the count on the safe side
• Boards = fence length × 12 ÷ (board width + gap), rounded up; panels = sections
• Post length = height above ground + hole depth

Concrete per post

Quikrete's post-setting instructions call for a hole 3 times the post width, a depth of 1/3 to 1/2 of the post height above ground, and about 6 in of gravel in the bottom. The calculator uses 3 × the post width and the 1/3 depth by default. Concrete fills the ring between the post and the hole above the gravel, and each hole is rounded up to whole bags because each hole is filled separately. Bag yields: about 0.375 cu ft for Quikrete Fast-Setting 50 lb, and about 0.30, 0.45 and 0.60 cu ft for Concrete Mix 40, 60 and 80 lb. Quikrete fills to 3 to 4 in below grade; the calculator fills to the top, so it leans slightly high.

Worked examples

100 ft privacy fence with one gate

6 ft tall, posts every 8 ft, a 4 ft gate, 3 rails, 5.5 in boards and 4×4 posts. The fence itself is 96 ft: 13 sections, 15 posts, 39 rails and 210 boards. Holes are 10.5 in wide and 24 in deep, so you need 8 ft posts. Each hole takes 3 bags of Fast-Setting mix, 45 bags in all. Narrow the hole to 10 in and the count drops to 2 bags per post (30 bags), which matches Quikrete's own figure of two 50 lb bags for a 10 in hole 2 ft deep. Digging 36 in deep instead needs 9 ft posts and 4 bags per hole.

U-shaped picket fence

Sides of 60, 120 and 60 ft, 4 ft tall, one 4 ft gate, 2 rails, 3.5 in pickets with a 2.5 in gap. That is 236 ft of fence, 31 sections, 33 posts, 62 rails and 472 pickets, with holes 16 in deep and 66 bags of Fast-Setting mix.

Closed yard with panels

Four sides of 50, 30, 50 and 30 ft, closed loop, 8 ft panels, one gate: 22 sections, so 22 panels and 23 posts, plus 69 bags.

Before you dig

Local frost depth, setbacks, height limits and HOA rules override any rule of thumb; check with your city or county and your HOA. Contact 811, the free national call-before-you-dig service, a few business days before digging and wait until buried utility lines have been marked. Slopes and stepped sections, bracing, post caps, hardware, gate kits and board-on-board overlap are not modeled. Our concrete and gravel calculators cover slabs and stone strips elsewhere in the yard.