Fence calculator

Work out the posts, rails, boards and concrete you need for a wood fence, and the materials cost if you add local prices.

How the numbers work

The fence is split into sections between posts. A straight run needs one more post than sections, and each corner adds another. Rails run between posts, two or three per section. Boards are the fence length divided by the board width plus any gap. Concrete is the volume of each post hole minus the post itself. We assume 4x4 posts (3½ in actual) and 80 lb bags that make 0.6 cubic feet each; see the concrete calculator for other bag sizes.

Questions

How many fence posts do I need?

Divide the fence length by the post spacing and round up to get the number of sections, then add one post to finish the run, plus one for each corner. A 100 ft straight fence with posts every 8 ft has 13 sections and 14 posts.

How many boards for a privacy fence?

Multiply the length in feet by 12 to get inches, then divide by the board width plus any gap. A 100 ft fence of 1x6 boards (5½ in actual width) with no gaps needs 219 boards.

How far apart should fence posts be?

6 to 8 feet is standard, with 8 ft the most common because rails come in 8 ft lengths. Use 6 ft spacing in windy areas or for heavy materials.

How deep should fence posts be?

A common rule is to bury about a third of the post's above-ground height, so roughly 2 ft for a 6 ft fence, and below the frost line in cold climates. Check local building requirements.

How much concrete per fence post?

For a 10 in hole 2 ft deep around a 4x4 post, about 0.92 cubic feet, which is roughly one and a half 80 lb bags.

Do I need to call before digging?

Yes. In the US, call 811 a few days before you dig so buried utility lines can be marked. It's free and it's the law in most states. Also check your property line and any HOA rules.

Materials estimate for a simple wood fence on level ground. Add 5–10% for waste, and add gate posts and hardware separately.