How to use the fence calculator
- Measure the full length of the fence line, including where the gates will go.
- Enter the post spacing. Wood fences commonly use 6 to 8 ft (about 1.8 to 2.4 m) between posts.
- Enter the number of gates and their width. Gate openings are not filled with rails or pickets.
- Enter the rails per section (often 2 for short fences and 3 for 6 ft privacy fences), the picket width and any gap between pickets. Use a gap of 0 for a privacy fence.
The formulas
Fence length = total length − (gates × gate width) Sections = fence length ÷ post spacing (rounded up) Posts = sections + 1 + one extra post per gate Rails = sections × rails per section Pickets = fence length ÷ (picket width + gap) (rounded up)Worked example
A 100 ft fence with one 4 ft gate, posts every 8 ft, 3 rails per section and 5.5 in pickets with no gap:
- Fence length: 100 − 4 = 96 ft, which is 96 ÷ 8 = 12 sections.
- Posts: 12 + 1 + 1 for the gate = 14 posts.
- Rails: 12 × 3 = 36 rails.
- Pickets: 96 × 12 = 1,152 in ÷ 5.5 = 209.5, so 210 pickets.
Tips
- Nominal 1×6 fence pickets are usually about 5.5 in wide. Measure the boards you plan to buy.
- Most fence posts are set in concrete. Use the concrete calculator with the post-hole option to estimate bags.
- Check property lines, local fence height rules and underground utilities before you dig.
Frequently asked questions
How far apart should fence posts be?
Wood fence posts are commonly spaced 6 to 8 feet apart. Closer spacing makes a stronger fence, especially in windy areas or for heavy privacy panels.
How many posts do I need for a 100 ft fence?
With posts every 8 ft and no gates, 100 ÷ 8 = 12.5, which rounds up to 13 sections and 14 posts. Each gate adds about one more post.
How deep should fence posts be set?
A common rule of thumb is to bury about one-third of the post's total length. In cold climates the hole should also go below the frost line, so check your local building code.
Should pickets have a gap?
Privacy fences are usually built with no gap, or with boards that overlap. Decorative picket fences usually leave a gap of a couple of inches between pickets for a lighter look.