HowMuchIt / Fence
How much fencing do I need?
A fence is counted in sections: the space between two posts. Measure each straight run, pick the post spacing, and the posts, rails and pickets follow. The hole size comes from the post itself.
Work out your fence
| Part | How |
|---|---|
| Posts | one per section, plus one to end each straight run |
| Rails | 2 per section up to about 4 ft high, 3 for a 6 ft fence |
| Pickets | length in inches / (picket width + gap) |
| Holes | a third of the post's length deep, 3 times its width across |
| Concrete | one 50 lb bag makes about 0.375 cu ft |
The concrete line takes the post's own volume out of the hole. Below the frost line, the local rule wins.
Walk the line first
Before any number, find out where your property line is: your survey shows it, and so does the local assessor's office. Then call 811 a few days before you dig. Buried gas, power and water lines get marked for free, and near a mark you dig by hand. Once you know where the fence goes, stake the corners, stretch a string between them and measure each straight run. A gate is part of a run: measure the run with the gate in it.
Posts, holes and concrete
Wood fence posts usually stand 6 to 8 feet apart, center to center. A straight run needs one post per section plus one to finish it, so five sections take six posts. Where two runs meet at a corner, one post serves both. Each hole goes about a third of the post's total length into the ground, so an 8 foot post needs a hole at least 2 1/2 feet deep, and in cold country it must reach below the frost line. Make the hole about three times as wide as the post. Type your post's real width, measured with a tape, and the calculator works out 50 lb bags of concrete for each hole.
Questions people ask
How many fence posts do I need?
Divide each straight run by the spacing and round up: that is the sections. Add one post per run. A 100 foot run at 8 feet is 13 sections and 14 posts.
How deep should a fence post hole be?
About a third of the post's total length, and below the frost line where the ground freezes. Is 2 feet enough? For a 6 foot post, yes; for an 8 foot post, go at least 2 1/2 feet.
How many pickets do I need?
Fence length in inches divided by the real picket width plus the gap. A 1x6 picket is 5 1/2 inches wide, a 1x4 is 3 1/2: use those, not the name on the tag.
How many bags of concrete per post?
It depends on the hole, which depends on the post. One 50 lb bag makes about 0.375 cubic feet, so the calculator measures each hole, takes the post out, and divides.
Good to know
- Space wood fence posts 6 to 8 feet apart, measured on center (from the center of one post to the center of the next).1,2,3,4
- Dig each post hole about one-third of the post's total length deep (an 8 ft post needs a hole at least 2 1/2 ft deep).2,3,5
- In cold climates, dig post holes below the local frost line, or frost can heave the posts out of the ground.1,2,3
- Make each post hole about 3 times as wide as the post.1,2,5,6
- Fences up to about 4 feet tall need 2 rails per section (top and bottom); taller fences such as a 6 ft privacy fence need a third rail in the middle.2,3,7
- A straight fence run needs one post per section plus one more post to end the run, so 5 sections take 6 posts.4,7
- Pickets sold as 1x4 are about 3 1/2 inches wide and 1x6 pickets about 5 1/2 inches wide; count with the actual width, not the name.1,8,9
- Number of pickets = fence length in inches divided by (actual picket width + gap between pickets).2,7
- Call 811 before digging so buried utility lines get marked, and hand dig within 18 to 24 inches of any mark.1,2,3
- Confirm where your property line is (your survey or the local assessor's office) before you lay out the posts.1,2,3,10
- One 50 lb bag of concrete mix makes about 0.375 cubic feet of concrete, so bags per post = hole volume (minus the post) / 0.375.5,6
How we checked this page
Checked on October 27, 2026. We kept a fact only when two independent publishers agree, and each one is numbered to its sources below. Where sources give different numbers, we keep only what they share. We never write a price. This page was written with an AI assistant and checked against the sources below.
Sources
- How to Build a Wood Fence, Lowe's
- How to Build a Fence, The Home Depot
- How to Build a Wood Privacy Fence in 8 Steps, Angi
- Fence Post Spacing: How Far Apart Should Fence Posts Be?, Decks.com (Trex Company)
- The Fastest (and Most Foolproof) Way to Install Fence Posts, Bob Vila
- QUIKRETE Fast-Setting Concrete #1004-50 (spec data PDF), Quikrete
- Fence Calculator - Building with Pickets (worksheet PDF), UFP Industries (Outdoor Essentials)
- Nominal vs actual lumber dimensions chart (PDF), Family Handyman
- Actual Sizes and Dimensions of Lumber, Hunker
- How to Build a Fence for Privacy (DIY), Family Handyman