Free tool · for homeowners, fence installers and contractors
Fence Calculator: How Many Posts, Pickets and Bags of Concrete Do I Need?
Enter each side of your fence, pick the fence type, height and gates, and get every post, rail, board or panel, the concrete for the post holes and the cost, in feet or meters.
Fence Calculator
- Fence line
Posts: one per section plus one at the end, with corners shared and one extra for each gate. Concrete follows Quikrete’s post-setting guide: concrete 1/3 of the post’s overall length deep (half the height above ground) on 6 in of gravel; holes default to 10 in for 4×4 wood posts (about 3× the post), 12 in for vinyl and 8 / 6 in for chain-link terminal / line posts. Dig below your frost line, call 811 before digging, and check your town’s fence height and setback rules.
How Do I Calculate How Much Fence I Need?
Measure each side of the fence line, divide by the post spacing and round up for the sections, then add one post at the end and one for each gate. 100 feet of fence with posts 8 feet apart needs 14 posts, 39 rails for a 6-foot fence, and about 230 privacy boards with 5% extra.
Checked against the sources below · How we build and test our calculators
Fence Post Calculator: Posts and Boards by Fence Length
One straight run, 6 ft wood privacy fence, posts 8 ft apart, 5.5 in boards with 5% extra.
| Fence length | Posts | Rails | Privacy boards | 80 lb concrete bags |
|---|---|---|---|---|
| 50 ft | 8 | 21 | 115 | 19 |
| 100 ft | 14 | 39 | 230 | 33 |
| 150 ft | 20 | 57 | 344 | 47 |
| 200 ft | 26 | 75 | 459 | 60 |
| 300 ft | 39 | 114 | 688 | 90 |
How to Calculate Fence Materials
- Measure each straight side of the fence line in feet.
- Sections: side length ÷ post spacing, rounded up. Add the sides together.
- Posts: sections + 1 for an open fence (corners are shared), + 1 for each gate.
- Rails: sections × 2 (up to 4 ft high), × 3 (5–6 ft) or × 4 (8 ft).
- Boards: fence length in inches ÷ (board width + gap), plus 5% extra.
- Concrete: hole volume minus the post, times the number of posts, ÷ the bag yield.
Concrete per Fence Post
| 4×4 post, 10 in hole | Cu ft | 40 lb bags | 50 lb bags | 60 lb bags | 80 lb bags |
|---|---|---|---|---|---|
| 24 in deep | 0.92 | 3.1 | 2.5 | 2 | 1.5 |
| 30 in deep | 1.15 | 3.8 | 3.1 | 2.6 | 1.9 |
| 36 in deep | 1.38 | 4.6 | 3.7 | 3.1 | 2.3 |
Bag yields: 50 lb about 0.375 cu ft (Quikrete Fast-Setting), 60 lb about 0.45, 80 lb about 0.6. Depth and gravel base from Quikrete’s post-setting guide.
Fence Types: Spacing and Materials
| Fence type | Typical post spacing | What you buy |
|---|---|---|
| Wood privacy | 6–8 ft | 4×4 posts, 2×4 rails, boards set edge to edge |
| Wood picket | 6–8 ft | 4×4 posts, 2 or 3 rails, pickets with gaps |
| Vinyl | Panel width, often 6 or 8 ft | 5×5 posts and ready-made panels |
| Chain link | Up to 10 ft (line posts) | Terminal and line posts, top rail, fabric rolls, tension bars and bands |
| Split rail | 10–11 ft | Mortised posts and 2 or 3 rails per section, often set without concrete |
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Questions
How many fence posts do I need?
Divide each side’s length by the post spacing, round up for the number of sections, and add one post at the end; corners are shared and each gate adds one more post. 100 feet of fence with posts 8 feet apart has 13 sections and needs 14 posts.
How many pickets do I need for 100 feet of fence?
For a privacy fence of 5.5-inch boards set edge to edge, 1,200 inches ÷ 5.5 = 219 boards, or 230 with 5% extra. For 3.5-inch pickets with 2.5-inch gaps it is 200 pickets, or 210 with 5% extra.
How much concrete do I need per fence post?
A 4×4 post in a 10-inch hole takes about 0.46 cubic feet of concrete per foot of depth. At 36 inches deep that is about 1.4 cubic feet: 2.3 bags of 80 lb or 3.7 bags of 50 lb fast-setting concrete. At 24 inches it is about 0.9 cubic feet, roughly 1.5 bags of 80 lb.
How deep should fence posts be?
Quikrete’s guide says the hole should be one-third of the post’s overall length, plus 6 inches for a gravel base. For a 6-foot fence that is about 3 feet of post in the ground, a 9-foot post. Always go below your area’s frost line and call 811 before digging.
How far apart should fence posts be?
Wood privacy, picket and vinyl fences usually have posts 6 to 8 feet apart (vinyl panels set the spacing, often 6 or 8 feet). Chain-link line posts are typically up to 10 feet apart, and split rail sections are usually 10 or 11 feet.
How many rails does a fence need?
Two rails per section for a fence up to 4 feet high, three for a 5- to 6-foot fence, and four for an 8-foot fence. Split rail fences use two or three rails per section.
How many posts for 30 meters of fence?
With posts 2.4 meters apart, 30 m ÷ 2.4 = 12.5, so 13 sections and 14 posts. Switch the calculator to meters to get posts, rails, boards and concrete for metric fencing.