Fence Calculator
Calculate fence posts, rails, pickets and concrete bags for a wood picket or privacy fence of any length.
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How to Calculate
Sections = fence length ÷ post spacing (rounded up). Posts = sections + 1 for a straight run; add a post for every corner and gate.
Pickets = fence length in inches ÷ (picket width + gap). Privacy fences use no gap.
Set posts about one-third of their above-ground height deep, typically 2–3 ft, with 1–2 bags of concrete each.
See our methodology for how every calculator on this site is built.
Worked Example: A 150 ft Privacy Fence
A 6 ft privacy fence, 150 ft long in a straight line, with posts every 8 ft, 3 rails per section, 5.5 inch pickets set tight with no gap, and 2 bags of concrete per post.
- Sections: 150 ÷ 8 = 18.75, round up to 19
- Posts: 19 + 1 = 20
- Rails: 19 × 3 = 57
- Pickets: (150 × 12) ÷ 5.5 = 1,800 ÷ 5.5 = 327.3, round up to 328
- Concrete: 20 × 2 = 40 bags
Real yards are rarely a straight line. If that fence turns two corners and has a 4 ft walk gate, add a post at each corner and one for the second gate post, then buy 5% to 10% extra pickets for culls. Pressure-treated lumber always has a few boards that are badly twisted or split.
Concrete per Post Hole
Numbers below subtract the volume of the post itself. Bags are 80 lb premix at about 0.6 ft³ each.
| Hole | Post | Concrete volume | 80 lb bags |
|---|---|---|---|
| 8 in diameter × 24 in deep | 4×4 | 0.53 ft³ | 1 |
| 10 in diameter × 30 in deep | 4×4 | 1.15 ft³ | 2 |
| 10 in diameter × 36 in deep | 4×4 | 1.38 ft³ | 2.5 |
| 12 in diameter × 36 in deep | 6×6 | 1.73 ft³ | 3 |
A good rule for hole size: about three times the post width in diameter. Gate posts and end posts carry more load and deserve the bigger hole.
Lessons from the Field
Call before you dig
Dial 811 a few business days before digging. The utility locate is free, and hitting a gas or power line with a post hole digger is not something you want to learn about the hard way.
Find the property line first
Many fence disputes come from guessing where the line is. Find the survey pins or get the survey from your closing papers. A lot of people set the fence a few inches inside their line on purpose.
Set end and corner posts first
Set and brace the end and corner posts, let them cure, then run a string line between them at the top and bottom. Every line post goes to the string. Setting posts one at a time by eye gives you a wavy fence.
Shed water at the base
Slope the top of the concrete away from the post so water runs off, and put a few inches of gravel at the bottom of the hole. Posts usually rot right at ground level, where they stay wet.
Plan for slopes
On a hillside, decide whether you'll step the sections or rack them to follow the grade. Stepped sections leave triangular gaps at the bottom; racked sections need pickets cut to follow the ground line. Both change your material list a bit.
Rough Cost
A DIY pressure-treated wood privacy fence often runs roughly $15 to $30 per linear foot in materials, and $30 to $60 per foot installed by a contractor, depending on height and region. Cedar costs more, and gates are priced separately.
Sources
Common questions
Frequently Asked Questions
How far apart should fence posts be?
6–8 feet. 8 ft is standard for wood fences; use 6 ft for heavy or tall panels and windy areas.
How many rails do I need?
Two rails for fences up to 5 ft tall, three rails for 6 ft privacy fences.
How deep should fence posts be?
At least 2 ft, or below the frost line in cold climates.
Should fence posts be set in concrete or gravel?
Concrete is standard and stiffest. Gravel drains better and makes replacing a rotted post easier; many pros use gravel at the bottom and concrete above.
Do I need a permit for a fence?
Many US towns require one for fences over 6 ft or in front yards, and HOAs often have their own rules. Check with your local building office before you dig.