Results update as you type. Round up when ordering.
Concrete based on about two 50 lb bags of fast-setting concrete per post (e.g. Quikrete Fast-Setting). Check the bag label.
Formula checked against manufacturer specs
Rounded up to whole units
Runs in your browser
How to plan a wood fence
Sections = fence length ÷ post spacing (rounded up); posts = sections + 1 for a straight run (add one for every corner, gate and end of a separate run). Rails = sections × rails per section. Pickets = fence length in inches ÷ (picket width + gap).
Example: 100 ft with 8 ft spacing: 13 sections, 14 posts, 39 rails (3 per section), and 100 × 12 ÷ 5.5 = 218.2 → 219 pickets for a privacy fence.
Rails: 2 or 3?
Fences up to about 4 ft usually use 2 rails; 6 ft privacy fences typically use 3 to reduce warping.
Setting posts
A common rule is to bury one-third of the post's above-ground height, and below the frost line in cold climates. Call 811 before you dig, and check HOA rules and local height limits.
It uses the standard formula shown on this page and rounds bags, boxes and pieces up to whole units. Product sizes vary by brand, so confirm with the label or your supplier before you buy.
Should I buy extra material?
Yes. A 5–10% allowance covers cuts, spills and uneven surfaces; running short mid-job usually costs more than a few leftovers.
Is this calculator free?
Yes. Every PorchMath calculator is free, needs no account and runs entirely in your browser.