Turn a fence line into a shopping list: posts (including gate posts), rails sized to the fence height, pickets or privacy boards for your width and gap, 50-pound concrete bags per post, and fasteners — with an optional cost estimate. Gates are subtracted from the fenced length, and a hole-size helper works out how much concrete each post really takes.
Setting posts in a lot of concrete? The concrete calculator handles bulk orders, and the gravel calculator covers drainage gravel under each post. Building a deck beside the fence? Try the deck calculator. How many bags make a yard, and when ready-mix beats bags, is covered in cubic yards, tons, and density.
Frequently asked questions
How many fence posts do I need?
Subtract gate openings from the total length, divide by the post spacing, and round up to get the number of sections. A gate splits the fence into two pieces that each usually end in a short section, so the calculator allows one extra section per gate and per separate run. You need one more post than sections for each piece of fence. A 100-foot fence with posts every 8 feet and one 4-foot gate works out to 13 sections and 15 posts (for example 50 ft + 46 ft either side of the gate = 7 + 6 sections). Corners land on posts already counted. Gate posts are often upgraded to 6×6 or set deeper.
How many pickets do I need for a fence?
Divide the fenced length in inches by the picket width plus the gap. For a privacy fence of 5½" boards butted tight, 100 feet takes 1,200 ÷ 5.5 = 219 boards. A picket fence of 3½" pickets with 2½" gaps takes 1,200 ÷ 6 = 200. Board-on-board (shadowbox) styles overlap alternating boards, so they need roughly one and a half to two times as many. Add about 5% for splits and bad boards. Wood shrinks as it dries, so boards installed tight can open small gaps within a season; spaced styles leave room for that movement. If you are matching an existing fence, measure a few boards, since actual widths vary by mill.
How many rails does a fence need?
Most wood fences use two horizontal rails (stringers) per section up to 4 feet tall, three for a 6-foot fence, and four for 8 feet, so the boards stay flat and resist warping. Rails usually span one post spacing, which is why 8-foot spacing pairs well with 8-foot 2×4s. You can override the count per section if your design uses a cap rail or a kick board. Rails are usually 2×4s set on edge or flat, fastened into or onto each post.
How much concrete do I need per fence post?
A common rule is two 50-pound bags per post for a 4×4 in a 10–12" wide hole. Quikrete recommends a hole about three times the post width and a third to half of the post's above-ground height deep — and always below your local frost line. The hole-size helper computes the fill volume (hole minus post) and divides by the 0.375 cubic-foot yield of a 50-pound bag, then you can apply that figure to every post. Many builders put a few inches of gravel in the bottom of each hole for drainage.
Should fence posts be 6 or 8 feet apart?
Eight feet is the most common spacing for wood privacy fences because rails come in 8-foot lengths. Six feet is stiffer and better for windy sites, heavy board-on-board fences, taller fences, and vinyl or picket panels sold in 6-foot widths. Shorter spacing means more posts and concrete but less sag. Check your local code and HOA rules for height limits, setbacks from the property line, and pool-barrier requirements. Whatever the spacing, call 811 a few days before digging so buried utility lines are marked, and set the corner and end posts first, then string a line between them to place the rest.