Fence Calculator

How the fence materials are calculated

Worked example: a 100 ft straight fence, 6 ft high

This uses 8 ft post spacing, three rails per section and tightly spaced 5.5 in pickets.

1. Sections: 100 ÷ 8 = 12.5, so 13 sections.
2. Posts: 13 + 1 = 14.
3. Rails: 13 × 3 = 39.
4. Pickets: 1,200 in ÷ 5.5 in = 218.2. With 5% spare, that's 230 pickets.
5. Each 10 in hole, 24 in deep, holds about 1.09 ft³. A 4×4 post takes up about 0.17 ft³ of that, leaving 0.92 ft³.
6. For all 14 holes: 12.9 ft³, or 35 of the 50 lb bags at 0.375 ft³ each.

Corners and gates

The formula assumes one straight run. A fence with corners has several runs, each ending at its own post. The simplest method is to enter each run separately, then subtract one post for each shared corner. Gates need their own posts, usually stronger ones, and the opening reduces the number of pickets. Pick the gate hardware first, since it sets the opening size.

How deep should fence posts go?

A common rule of thumb is to bury about one-third of the post's total length, but your local frost line and soil conditions come first. In areas with frost, holes generally need to go below the frost line so the ground doesn't heave the posts. Your local building department can give you the required depth, and may also have rules on fence height and setbacks.

Before you dig

• Call your utility locator service first. In the US, dial 811 a few days before digging.
• Confirm your property line. A survey is cheaper than moving a fence.
• Check for HOA rules and permit requirements on height, style and setback.
• Use posts and rails rated for ground contact where they will touch soil or concrete.
• Check picket width by measuring one. Nominal and real widths differ.

Need concrete for something else, such as a gate pad? Try the concrete calculator. Building a deck too? The deck board calculator handles the surface.