Fence Calculator
Use this fence calculator to estimate sections, posts, rails, pickets, concrete bags, waste, and optional material cost for a wood or picket fence. Enter the fence length, post spacing, gate details, board size, and concrete bags per post.
Results
Fence layouts vary in the field. This calculator treats each gate as adding two gate posts, and it estimates pickets as full sections. A shorter last section can make the picket count a little high, which is usually better than coming up short.
How to use this calculator
- 01Enter the total fence length, including gate openings.
- 02Set post spacing, fence height, number of gates, and gate width.
- 03Enter rails per section, picket width, picket gap, waste, and concrete bags per post.
- 04Add material prices if you want a cost estimate.
- 05Read the sections, posts, rails, pickets, concrete bags, and material cost.
Understanding the math
The calculator starts with total fence length, subtracts gate openings, then divides the remaining run into post-spaced sections. It treats each gate as adding two gate posts. Picket count is based on full sections, so a shorter last section may leave a few extra boards.
Total gate width = gate count x gate width Adjusted fence length = max(total length - total gate width, 0) Sections = adjusted fence length / post spacing Posts = sections + 1 + gate count x 2 Rails = sections x rails per section Pickets per section = post spacing / (picket width + gap) Pickets to buy = pickets before waste x (1 + waste / 100) Concrete bags = posts x bags per post
Example: a 100 ft fence with one 4 ft gate has 96 ft of fence run. With 8 ft post spacing, that makes 12 sections, 15 posts, 24 rails at two rails per section, and 225 pickets with 10 percent waste.
Fence quick reference
Use these common fence values as a starting point, then adjust the calculator to match your material and site.
| Item | Value | Notes |
|---|---|---|
| Common post spacing | 6 to 8 ft | Shorter spacing gives a stiffer fence and more posts |
| Typical privacy fence height | 6 ft | Check local rules before building near a property line |
| Common picket width | 5.5 in | Use actual board width, not the nominal lumber name |
| Typical picket gap | 0 to 0.25 in | Privacy fences often use little or no visible gap |
| Rails per section | 2 to 3 | Tall or heavy fences often use three rails |
| Default waste factor | 10% | Covers cuts, damaged boards, and layout variation |
| Concrete bags per post | 1 to 2 bags | Hole diameter, depth, and soil conditions change this number |
Frequently asked questions
How to calculate linear feet for fence?
Measure the fence line along the planned layout. Add each straight run together, including the spaces where gates will go. The calculator subtracts gate width from the board run, but the full measured length is still the starting point.
How many fence posts do I need?
Divide the fence length after gate openings by post spacing, then round up for sections. Posts are sections plus one, with two added posts for each gate. Real gate layouts vary, so confirm the final post plan before digging.
How far apart should fence posts be?
Most wood fences use 6 to 8 ft post spacing. Shorter spacing makes a stiffer fence and adds posts. Taller fences, windy sites, and heavy boards may need tighter spacing.
How many rails do I need for a fence?
Multiply fence sections by rails per section. A common 6 ft privacy fence uses two rails per section, while taller or heavier fences often use three.
How many pickets do I need for a fence?
Add the picket width and gap, then divide post spacing by that combined width. Round up for pickets per section, multiply by sections, and add waste. The last section may be shorter, so this can slightly overcount.
How many bags of concrete do I need for fence posts?
Multiply the number of posts by the bags per post, then round up. One to two bags per post is a common estimate, but hole diameter, depth, soil, and local frost depth can change the amount.
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