Fence Calculator

Posts, rails, pickets or panels, concrete bags and gate hardware for a wood, vinyl or chain-link fence. Enter the length, height, corners and gates, and get a shopping list with stain and labour estimates.

A wood privacy fence being built: posts set in concrete, rails on, pickets going up A fence line on 8 ft post spacing, shown with the ground cut away so each post can be seen in its concrete footing on a gravel base. The first bay is finished with dog-ear pickets and post caps, pickets are being nailed one by one to the three rails of the second bay, and in the third bay a string line runs between the posts while the last post is braced, brought to plumb with a post level, then concreted. A post-hole digger stands in the spoil pile next to bags of fast-setting concrete. FAST-SETTINGCONCRETE MIX50 LB FAST-SETTINGCONCRETE MIX50 LB

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Fence reference

6′3′6″10–12″ POST CAP KEEPS END GRAIN DRY2×4 RAIL, 2–3 SCREWS EACH END4×4 POST: ⅓ OF ITS LENGTH IN GROUNDCONCRETE CROWNED TO SHED WATERHOLE ≈ 3× POST WIDTHFROST LINE: HOLE GOES BELOW4–6″ GRAVEL: POST END DRAINS1×6 PICKETS, 2 NAILS PER RAIL2″ CLEAR
Typical detail for a 6 ft wood fence. Post depth and footing size follow local code and frost depth.

Posts

Spacing
6–8 ft on center
Line, corner, end
4×4 (6×6 at 8 ft tall)
Gate posts
6×6, hole 2 in wider
In the ground
⅓ of post length
Hole diameter
3× post width
Hole bottom
below frost depth

Rails and pickets

Rails, 4 ft fence
2 per bay
Rails, 5–8 ft fence
3 per bay
Rail stock
2×4, joints on posts
Pickets above grade
about 2 in
Picket fasteners
2 per rail
Rail to post
2–3 screws per end

Concrete and gravel

50 lb fast-setting
≈ 0.375 ft³
60 lb / 80 lb mix
0.45 / 0.60 ft³
Fast-setting
sets in 20–40 min
Rails and pickets on
after about 4 h
Gravel under post
4–6 in
Collar top
crowned above grade

Finish and paperwork

Lumber
ground-contact rated
Nails and screws
hot-dip galv. or stainless
Stain coverage
≈ 150–200 ft²/gal
Stain treated wood
once it is dry
Call 811
a few days before digging
Height limits
check code, HOA

Before you dig Call 811 a few working days ahead so buried lines are marked. Confirm the property line (survey pins or a plat), and check permit, height and HOA rules before you buy materials. Concrete is caustic: wear gloves and eye protection.

Full notes
  • Count corners, ends and gate posts separately: they take the load of the fence and the gate, so they get bigger holes and, for gates, 6×6 posts.
  • Rule of thumb for post depth: about one third of the post length in the ground (2 ft for a 4 ft fence, 3 ft for 6 ft), and always below your local frost depth.
  • Set the end and corner posts first, run a string line between them, and set the line posts to the string so the fence is straight and the posts are in plane.
  • Pour fast-setting concrete dry into the hole around a braced, plumb post, then add about a gallon of water per 50 lb bag. Crown the top above grade so water runs away from the post.
  • Put 4–6 inches of gravel in the bottom of each hole so the end grain of the post can drain instead of sitting in a cup of water.
  • Let pressure-treated lumber dry before staining (water should soak in, not bead). Use hot-dip galvanized or stainless fasteners: treated wood corrodes plain steel.

Planning a bigger project?

Concrete CalculatorHow many cubic yards of concrete, or how many 40, 60 and 80 lb bags, you need for a slab, patio, walkway, footing pad or round pier.Gravel CalculatorCubic yards and tons of gravel for a driveway, path, drainage trench or patio base.Paint CalculatorHow many gallons of paint and primer a room needs from its size, ceiling height, doors, windows and coats, rounded to what you actually buy.