Fence Calculator
Plan your fence build without surprises. Enter total fence length, post spacing, and picket details to get exact counts of posts, rails, pickets, and concrete bags.
Post height: 8 ft (6 ft fence + 2 ft buried). Post size: 4x4.
How to use Fence Calculator
The fence calculator estimates the number of posts, rails, pickets and concrete bags needed for any fence length. Enter the total run, post spacing, picket width and rails per bay to get a complete materials list with waste factor.
- Enter total fence length in feet.
- Set post spacing (6 or 8 ft on-centre is standard).
- Enter picket width and gap between pickets.
- Choose number of rails per section.
- Review posts, rails, pickets and concrete bags.
Your data never leaves your device — 100% private processing.
Post sizing, depth and concrete
Post diameter and depth depend on fence height. For a 6-ft privacy fence, use 4×4 posts set 2 ft deep (or below frost line, whichever is deeper). Use 8-ft posts to allow a 2-ft bury plus a 6-ft above grade. In frost zones (most northern US), set posts 42"+ deep to prevent heaving. Each post hole requires 1–2 bags of fast-setting concrete (50–60 lbs each) depending on hole diameter.
| Fence height | Post size | Bury depth | Post length needed |
|---|---|---|---|
| 3 ft (garden) | 4×4 | 18" | ~5 ft |
| 4 ft (picket) | 4×4 | 24" | ~6.5 ft |
| 6 ft (privacy) | 4×4 or 6×6 | 24–30" | ~8.5 ft |
| 8 ft (tall privacy) | 6×6 | 30–36" | ~11 ft |
Gate framing and hardware
Gates require extra-strong posts (at least 6×6 for a double gate) and gate-specific hardware: heavy hinges (3 minimum for a 6-ft gate), a gate latch, and a drop rod for double gates. Gates wider than 4 ft need diagonal bracing to prevent racking. Allow a 1/2" gap all around for seasonal wood movement.
Glossary
- On-centre (OC)
- Distance from the centre of one post to the centre of the next.
- Frost line
- The depth below which soil does not freeze; posts must be set below this level.
- Picket
- The vertical boards forming the fence face; can be flat, dog-eared or pointed.
- Racking
- Lateral leaning or distortion of a gate or fence panel under side loads.
Related reading
Frequently Asked Questions
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Why use Fence Calculator?
- Accurate material estimates reduce waste and over-ordering
- Supports both metric and imperial measurements
- Covers common materials: concrete, lumber, flooring, paint
- Results include waste factor buffers for professional accuracy
Common use cases
- Calculate concrete needed for a driveway
- Estimate flooring tiles for a room renovation
- Work out paint quantity for interior walls
- Calculate lumber needs for a deck project
- Estimate roofing material for a pitched roof
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