Fence Calculator
This fence calculator works out how many posts, rails and pickets you need for a wood fence, plus the bags of concrete to set the posts. Enter the fence length, post spacing and number of gates.
Result
15 posts, 39 rails, 234 pickets
| Sections | 13 |
|---|---|
| Pickets per section | 18 |
| Concrete, 80 lb bags | 38 |
| Or 60 lb bags | 50 |
| Post concrete (incl. 10%) | 0.83 yd³ (22.5 ft³) |
Results update as you type.
How Much Fencing Material Do I Need?
A wood fence is a row of identical sections. Work out how many sections fit along the fence line and you can count everything else from that: one post per section plus an end post, rails per section, and pickets per section. The calculator also works out the concrete to set every post.
How to Calculate Fence Materials by Hand
1. Sections
Sections = fence length ÷ post spacing, rounded up
2. Posts
Posts = sections + 1 + number of gates
3. Rails
Rails = sections × rails per section
4. Pickets
Pickets per section = (post spacing × 12) ÷ (picket width + gap), rounded up Pickets = pickets per section × sections
5. Post concrete
Each hole is a cylinder: 3.1416 × (diameter (in) ÷ 24)² × depth (ft) cubic feet. Multiply by the number of posts, add 10%, and divide by 0.6 for 80 lb bags.
Worked example: a 48 ft picket fence
A front-yard picket fence with posts 6 feet apart, no gates, 2 rails, 3.5 inch pickets with 2.5 inch gaps, and 10 inch holes 2.5 feet deep:
- Sections: 48 ÷ 6 = 8
- Posts: 8 + 1 = 9
- Rails: 8 × 2 = 16
- Pickets: 72 ÷ 6 = 12 per section, × 8 = 96 pickets
- Concrete: 1.36 ft³ × 9 posts × 1.10 = 13.5 ft³, ÷ 0.6 = 22.5, rounded up to 23 bags of 80 lb mix
Tips & Common Mistakes
Call before you dig
In the US, call 811 or file a request online a few days before you dig. Utility lines are marked for free. Hitting a gas or power line while digging post holes is dangerous and expensive.
Know where your property line is
Fences built on the wrong side of the line cause neighbor disputes and can be ordered removed. Find your survey pins or check your plat, and many people set the fence a few inches inside the line. HOAs often control height and style, too.
Corners: run each side separately
The calculator treats the fence as one straight run. For a fence with corners, run each straight side through it and add the results, then subtract one post for each shared corner. One 100 ft entry instead of two 50 ft sides undercounts posts.
Gate openings
If you know the gate widths, subtract them from the fence length so you don’t buy pickets for the gap. Buy gate hardware and any prebuilt gate panels separately.
Gravel in the bottom of the hole
A few inches of gravel at the bottom of each hole lets water drain away from the end of the post. Our gravel calculator handles the stone. For deeper or wider holes than usual, the concrete calculator lets you work out post holes on their own.
Frequently Asked Questions
How many fence posts do I need for 100 feet?
With posts 8 feet apart, 100 feet makes 13 sections and needs 14 posts, plus one more for each gate. With 6 foot spacing it is 17 sections and 18 posts. If the fence has corners, count each straight run separately.
How far apart should fence posts be?
Six to eight feet on center is standard for wood fences. Eight feet suits standard 8 foot rails. Use closer spacing for tall privacy fences in windy areas or on slopes, and for heavy materials. Check your local code and any HOA rules.
How deep should fence posts be set?
A common rule is to bury about a third of the post's total length. For a 6 foot fence on 8 foot posts, that is about 2.5 to 3 feet. Where local code requires it, go below the frost line, which is deeper in cold climates.
How many bags of concrete do I need per fence post?
A 10 inch wide, 2.5 foot deep hole holds about 1.4 cubic feet. With 10% extra, that is 1.5 cubic feet, so plan on 3 bags of 80 lb concrete per post. For a whole fence, enter all your posts here. The total rounds up once, which avoids buying a part-used extra bag for every hole.
How many pickets are in an 8 foot fence section?
For a privacy fence with 5.5 inch pickets butted tight, an 8 foot section takes 18 pickets. With 3.5 inch pickets and a 2.5 inch gap, it takes 16. Use your own picket width and gap in the calculator.
How many rails does a fence need?
Two rails per section is common for fences up to about 4 feet tall. Six foot privacy fences usually use three rails, which keep the pickets from warping. Very tall fences may need four.
Do gates need extra fence posts?
Yes. A gate splits a run, so each gate adds a post, and gate posts carry more load than line posts. Set gate posts deeper and with more concrete than line posts.
Related Calculators
Sources & Assumptions
- Sections = fence length ÷ post spacing, rounded up; posts = sections + 1 + gates; rails = sections × rails per section; pickets = ceil(section width ÷ (picket width + gap)) × sections.
- Post concrete uses the same bag yields as our concrete calculator (Quikrete Concrete Mix No. 1101 data sheet — 0.60 ft³ per 80 lb bag, 0.45 ft³ per 60 lb bag) with 10% waste.
- HGTV, How Deep Should I Dig Fence Posts? — set about one third of the post's length in the ground
- Concrete volume ignores the space taken up by the post, which gives a small extra margin.
- Counts always round up.
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