# Fence Calculator

To estimate a fence, divide the length by the post spacing and round up for sections, then add one post plus one per gate. Rails are sections × rails per section; pickets are the fenced length in inches ÷ (picket width + gap). 150 ft of 6 ft privacy fence at 8 ft spacing takes 21 posts and 319 pickets.

## Key takeaways

- Posts = ⌈length ÷ spacing⌉ + 1, plus one latch post per gate.
- Pickets = picketed length (in) ÷ (picket width + gap). A nominal 1×6 picket is 5.5 in wide.
- QUIKRETE's rule: post holes about 3× the post width, and 1/3 of the post's total length in the ground (half the above-ground height), plus 6 in of gravel.
- A 6 ft fence on 4×4 posts needs 36 in of embedment and about 1.4 cu ft of concrete per post.
- Frost depth, wind exposure and local code can require deeper holes. Check before you dig.

## How do you calculate fence materials?

Work from the fence line out: sections from the post spacing, posts from the sections and gates, rails from the sections, pickets from the length you'll actually cover, then post holes and concrete from the post size and fence height.

**Formula**

```
Posts = ⌈L ÷ S⌉ + 1 + G;  Pickets = ⌈(L − G × Wg) × 12 ÷ (P + gap)⌉
```

Where:
- L = fence length in feet, including gates
- S = post spacing on center in feet
- G, Wg = number of gates and gate width in feet
- P = actual picket width in inches
- gap = space between pickets in inches (0 for privacy)

1. **Measure the fence line.** Walk the line and measure each straight run. Corners, ends and gate posts are fixed points; lay out spacing between them.
2. **Count sections and posts.** Divide each run by the post spacing and round up. Add one post to close the run and one extra for each gate's latch side.
3. **Count rails.** Multiply sections by rails per section. Many 6 ft privacy fences use 3 rails; shorter fences often use 2.
4. **Count pickets.** Subtract gate openings, convert to inches and divide by picket width plus gap. Add a few for culls.
5. **Size the holes and concrete.** Hole diameter about 3× the post width, embedment half the above-ground height, plus 6 in of gravel. Work out concrete from the hole volume minus the post.

> **Worked example: 150 ft privacy fence**
>
> 150 ft of 6 ft wood privacy fence with posts every 8 ft and one 4 ft gate. Sections: 150 ÷ 8 = 18.75, round up to **19**. Posts: 19 + 1 + 1 for the gate = **21**.
>
> Rails: 19 × 3 = **57** rails of 8 ft.
>
> Pickets: 146 ft (less the gate) × 12 ÷ 6 in = **319 pickets**, plus the gate's own.
>
> Post holes for 4×4 posts: 10.5 in across, 36 in of embedment plus 6 in of gravel, so dig 42 in. Concrete fills to 3 in below grade: 1.42 cu ft per post, or **4 bags of 50 lb fast-setting mix** (84 total). With 80 lb concrete mix it's 3 bags per post, 63 total.

## How deep should fence posts be?

QUIKRETE's guidance is to set posts 1/3 of their overall length in the ground, which works out to half the fence height above ground: 36 in for a 6 ft fence on a 9 ft post. Its how-to video gives 1/3 to 1/2 of the above-ground height, with at least 2 ft for a 6 ft fence. Add 6 in for a gravel base. Where the ground freezes, local code or the inspector may require holes below the frost line.

**Post-hole size and concrete per post (50 lb fast-setting mix)**

| Post | Fence height | Hole diameter | Hole depth | Bags per post |
| --- | --- | --- | --- | --- |
| 4×4 | 4 ft | 10.5 in | 24 in + 6 in gravel | 3 |
| 4×4 | 6 ft | 10.5 in | 36 in + 6 in gravel | 4 |
| 4×4 | 8 ft | 10.5 in | 48 in + 6 in gravel | 6 |
| 6×6 | 6 ft | 16.5 in | 36 in + 6 in gravel | 10 |
| 6×6 | 8 ft | 16.5 in | 48 in + 6 in gravel | 13 |

_Computed with the calculator above using QUIKRETE's 3× diameter and 1/3-of-post-length rules and 0.375 cu ft per 50 lb bag._

## How much fence for common jobs?

**Fence materials by job (one 4 ft gate each, 4×4 posts unless noted, 50 lb fast-setting mix)**

| Fence | Length | Posts | Rails | Pickets | Concrete bags |
| --- | --- | --- | --- | --- | --- |
| 6 ft privacy, 8 ft spacing, 1×6 | 100 ft | 15 | 39 | 210 | 60 |
| 6 ft privacy, 6 ft spacing, 1×6 | 100 ft | 19 | 51 | 210 | 76 |
| 4 ft picket, 1×4 with 2.5 in gap | 100 ft | 15 | 26 | 192 | 45 |
| 6 ft privacy, backyard | 200 ft | 27 | 75 | 428 | 108 |
| 8 ft privacy, 6×6 posts | 150 ft | 21 | 57 | 319 | 273 |

_Computed with the calculator above. Pickets don't include the gate itself._

## What post spacing should I use?

Most wood privacy fences use posts 6 to 8 ft on center, set so 8 ft rails and panels land on posts. University of Georgia Extension's farm fencing guide shows 4-rail board fence with posts spaced 8 ft and line posts set at least 2 ft deep. Tighter spacing adds posts and concrete but stiffens tall fences in windy, exposed yards.

## Common fence estimating mistakes

1. **Forgetting the extra post.** Sections + 1, not sections. Every gate adds a latch post.
2. **Using nominal picket widths.** A 1×6 is 5.5 in. Using 6 in under-counts by about 8%.
3. **Not checking the property line and utilities.** Call 811 before digging and confirm the line before setting the first post.
4. **Shallow holes.** A post with too little embedment leans in the first wind. Follow the 1/3 rule at minimum, deeper where frost or code requires.
5. **Skipping hardware and fasteners.** Gate hinges, latches, rail brackets and nails or screws are a real line on the quote.

BRIX turns the post, picket and concrete counts into a quote you can send from the driveway, then follows up until the homeowner signs.

- [Quotes and estimates](https://www.brix.so/features/quotes-estimates): Builds accurate quotes on site and follows up on every open estimate.
- [Sales automation](https://www.brix.so/features/sales-automation): Follows up every lead and open estimate automatically by text and email, and asks every customer for a review after the job.

## Frequently asked questions

### How many fence posts do I need for 100 feet?

At 8 ft spacing, 100 ft is 12.5 sections, rounded up to 13, so you need 14 posts plus one for each gate. At 6 ft spacing it's 17 sections and 18 posts.

### How many bags of concrete per fence post?

It depends on hole size. For a 6 ft fence on a 4×4, a 10.5 in hole with 36 in of embedment takes about 1.4 cu ft of concrete: 4 bags of 50 lb fast-setting mix or 3 bags of 80 lb concrete mix. QUIKRETE says two 50 lb bags set a 3 in post in a 9 in hole 30 in deep.

### How deep should a 6 foot fence post be?

QUIKRETE's rule is 1/3 of the post's overall length, which is 36 in for a 6 ft fence on a 9 ft post, plus 6 in of gravel. Its video guidance allows at least 2 ft. Go below the frost line where code requires it.

### How many pickets do I need for a privacy fence?

Divide the fenced length in inches by the actual picket width. For 100 ft of 5.5 in pickets with no gap, that's 1,200 ÷ 5.5 = 219 pickets. Add a few extra for split or warped boards.

### How far apart should fence posts be?

Usually 6 to 8 ft on center for wood fences, matched to your rail or panel length. Use closer spacing for tall fences, heavy gates or windy sites.

## Related

- [Concrete Calculator](https://www.brix.so/tools/concrete-calculator)
- [Gravel Calculator](https://www.brix.so/tools/gravel-calculator)
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## Sources

- [QUIKRETE — Fast-Setting Concrete Mix data sheet (yield, hole size and depth)](https://www.quikrete.com/PDFs/DATA_SHEET-Fast%20Setting%20Concrete%20Mix%201004-50.pdf) (checked 2026-10-12)
- [QUIKRETE — Setting Posts project guide](https://www.quikrete.com/PDFs/Projects/SettingPosts.pdf) (checked 2026-10-12)
- [QUIKRETE — Setting Posts without Mixing](https://www.quikrete.com/AtHome/Video-Setting-Posts.asp) (checked 2026-10-12)
- [QUIKRETE — Concrete Mix No. 1101 data sheet (80 lb yield)](https://www.quikrete.com/PDFs/DATA_SHEET-Concrete%20Mix%201101.pdf) (checked 2026-10-12)
- [University of Georgia Extension — C774, Fences for the Farm](https://fieldreport.caes.uga.edu/publications/C774/) (checked 2026-10-12)

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Written by BRIX Editorial Team. Last updated 2026-10-12.
Canonical: https://www.brix.so/tools/fence-calculator