How much fence material do you need?

Divide the run length by your post spacing and round up to get the number of sections, then add one (a fence always needs one more post than sections), plus two extra posts for every gate. With 8-foot spacing, a 100-foot run is 13 sections, so 14 line/end posts plus gate posts. Closer spacing (6 feet) is recommended for tall or high-wind fences.

For a side-by-side privacy fence using 5.5-inch boards with a small 0.5-inch gap, you need roughly 2.2 pickets per linear foot — about 16 per 8-foot section. This calculator subtracts your gate openings from the run first, then adds a 10% lumber waste factor, so a 100-foot privacy run works out to about 220 pickets.

Use the height as your guide: fences up to 4 feet typically use 2 rails, 5 to 7 feet use 3 rails, and 8 feet uses 4 rails (about one rail per 24 inches of height, with a minimum of two). Rails tie the posts together and carry the pickets.

A standard 4×4 post in a 10-inch hole dug 2 to 3 feet deep usually takes about two 60-pound bags of fast-setting concrete. Corner, end, and gate posts carry more load and often get three. This calculator estimates two bags per post as a starting point.

A common rule is to bury about one-third of the post's total length, and always below your local frost line so the posts don't heave. Add a few inches of gravel at the bottom of each hole for drainage. Check local code and call 811 before digging.