Fence Calculator & Deck Calculator
Planning a fence or a deck? Enter your dimensions and get a complete materials list — pickets, posts, rails, and concrete for a fence; boards, joists, and screws for a deck. Two calculators in one page, free, running entirely in your browser.
Estimates assume a straight run with standard materials. Gates, slopes, stairs, ledger boards, and permits add materials not counted here — confirm local fence-height and permit rules before you dig.
Frequently Asked Questions
How many fence pickets do I need?
Convert your fence length to inches and divide by (picket width + gap). A 100-ft privacy fence with 5.5-inch pickets and no gap needs (100 × 12) ÷ 5.5 = 218.2, rounded up to 219 pickets. Wider gaps shrink the count fast — a 1-inch gap on the same fence drops it to 185 pickets.
How many fence posts do I need?
Divide the fence length by your post spacing, round up, and add one for the end post. A 100-ft fence with 8-ft sections needs ceil(100 ÷ 8) + 1 = 13 + 1 = 14 posts (the last section comes up a little short). Add extra posts for corners and gates.
How many deck boards do I need?
Boards run along the deck's length, so divide the deck's width (in inches) by (board width + gap). A 12-ft-wide deck with 5.5-inch boards and ¼-inch gaps needs (12 × 12) ÷ 5.75 = 25.04, rounded up to 26 boards — each as long as the deck itself. Buy 5–10% extra for cuts and defects.
How far apart should deck joists be?
16 inches on center is the standard for 5/4-inch decking and most composite boards. Use 12-inch spacing for diagonal decking patterns or thinner boards. The calculator above counts joists for either spacing.
How much concrete per fence post?
One 80-lb bag per post is the common rule for a typical 4×4 post in a 10-inch-diameter, 3-ft-deep hole. Softer soil or taller fences (6 ft+) deserve two bags per post for stability.
How many screws do I need for a deck?
A good rule is 2 screws per board at every joist. Multiply your board count by your joist count by 2. A 26-board deck on 13 joists needs 676 screws — sold in 5-lb boxes of roughly 350–400, so two boxes covers it with spares.