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Fence Calculator

Enter total fence length for post count, rails, boards, concrete bags and gate hardware — for any fence style.

Total fence length
Fence style
Post spacing
Rails per span
Board width
Gate sets
Waste allowance10%

14 posts · 29 rails · 378 boards · 28 concrete bags

You'll need
14 posts
fence posts needed
+ 28 bags of 60 lb bags

100 lin ft · 8 ft post spacing · 2 rails · 10% waste.

Materials list

Concrete bags (60 lb)28 bags
2 bags per post hole · set posts in concrete for stability
Fence rails (8 ft)29 rails
8 ft rails · 2 rails per span · use pressure-treated lumber
Privacy boards378 boards
3.5 in wide · use pressure-treated or cedar for longevity
Post caps14 capsoptional
Caps prevent water from sitting on end grain — extends post life significantly
Gate hardware kits1 kit
Each kit includes 2 hinges + 1 latch — use heavy-duty hardware for larger gates
Fence stain / sealer2 galoptional
~300 sq ft per gallon · both sides of a 6 ft fence · apply within first season
Fence screws / nails16 lboptional
~4 fasteners per board (2 per rail) · 1-5/8 in or 2 in deck screws
Gravel for post drainage14 bagsoptional
4–6 in of gravel at bottom of post hole before setting post extends life

Tools you'll want

Buy-once items — skip any you already own.

Post hole digger
Rent a gas auger for more than 6 posts — saves hours.

Where to buy (optional)

Happy with your list? Tap any item below to open it at a retailer. These are affiliate links that support the site at no extra cost — but shop wherever you like.

Estimates only — verify quantities before buying.

How to calculate fence materials

Fence material quantities start with post count, then derive rails and boards from post spacing:

posts = ceil(fence length ÷ post spacing) + 1
spans = posts − 1
rails = spans × rail count × ceil(spacing ÷ 8 ft)
boards = ceil(fence length × 12 in ÷ board width) × (1 + waste%)

Concrete: 2 × 60 lb bags per post. Rails are priced as 8 ft treated lumber; privacy boards as 1×4 dog-ear boards. Always add extra boards for future repairs.

Common mistakes

  • Setting posts too shallow — must go below frost depth to prevent heaving in cold climates.
  • Installing before calling 811 — always request a utility locate before digging post holes.
  • Not checking property lines — a fence on the neighbour's property is a legal problem.
  • Using non-ground-contact lumber for posts — use UC4B or UC4C rated PT for in-ground use.

Frequently asked questions

How many fence posts do I need for 100 feet of fence?+

At 8 ft post spacing, a 100 ft fence needs 13 posts (100 ÷ 8 = 12.5 sections, plus the final end post = 13 posts). Add one more for each gate opening and always round up — running out of posts mid-project means extra trips.

How deep should fence posts be set?+

The standard rule is one-third of the total post length below ground. For a 6 ft fence you need 8 ft posts with at least 2 ft in the ground (deeper in cold climates to get below the frost line). Check your local frost depth — shallow posts heave out of the ground over winter.

How many concrete bags do I need per fence post?+

Two 60 lb bags per post hole is standard for 4×4 posts in 10-in diameter holes at 2 ft depth. For 6×6 posts or deeper holes, use 2–3 bags of 80 lb concrete. Dry-set method (pouring dry concrete in the hole and watering from the top) works well for fence posts.

How many pickets are in a privacy fence for 100 feet?+

With standard 3.5 in dog-ear boards and no gap (butted tight), a 100 ft privacy fence needs about 343 boards (100 ft × 12 in/ft ÷ 3.5 in). Adding 10% waste gives 378 boards. The calculator handles this automatically based on your picket width.

How long does a fence post last in the ground?+

Pressure-treated pine posts rated for ground contact (UC4B or UC4C) typically last 20–40 years. Cedar posts last 15–20 years. Setting the post in concrete actually shortens life slightly because water pools at the concrete-wood interface. Use concrete only at the surface; pack gravel at the bottom for drainage.

Do I need a permit to build a fence?+

Many municipalities require a permit for fences over 6 ft tall, for fences near property lines, or in front yards. Some areas have HOA rules too. Always check with your local building department and HOA before installing. A fence in the wrong location can be costly to move.

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Reviewed by the RenoSheets team for calculation accuracy. Method: linear fence length divided by post spacing plus 1; rails and boards derived from span count. Last updated 2026-05-26. Estimates only — verify quantities before purchasing.