Free calculator
Fence calculator
Enter the run, the height and the post spacing, pick privacy, picket or post-and-rail, and get posts, rails, boards, screws and the bags of concrete for the post holes.
Result
- Posts
- 14
- Post length to buy
- 8 ft (needs 8 ft)
- Rails (8 ft pieces)
- 43 (39 + waste)
- Boards
- 241 (219 + waste)
- Screws or nails
- 1,314
- Concrete per post
- 1.01 cu ft, 2 × 80 lb bag
- Concrete bags in total
- 28
Sections are rounded up, so the last one is shorter. Board counts use the face width you enter; rails are counted as one piece per section. Concrete per hole includes 10% for uneven digging.
Quoting this job for a client? Pro builds the quote for you.
Labour, extra items, margin and tax on top of the material list. Printed with your logo, saved as PDF. Works from the 3D room planner.
How it works
The run is divided into sections at the post spacing (8 ft is usual for a privacy fence, 6 ft where the panels are heavy or the wind is strong) and rounded up, so the last section is shorter. A straight run has one more post than sections; each gate takes its opening out of the boards and adds a post. Rails are counted as one piece per section per rail, and boards as the fenced length divided by the board width plus the gap, with the waste you allow for cuts and rejects.
Post depth follows the usual rule of a third of the height in the ground and never less than 2 ft, which the field suggests from the height you type; go deeper where the frost line is lower, which your local code sets. The post length to buy is height plus depth, rounded up to the 2 ft steps lumber comes in. Concrete per hole is the hole cylinder minus the post that sits in it, plus 10% for uneven digging, converted to bags with the yield printed on the bag in the concrete calculator.
Fasteners are two per board per rail. Post caps, gate hardware, gravel for the bottom of the holes and the stain or sealer are not counted; the stain guide covers the last one.
Frequently asked questions
- How many fence posts do I need for 100 feet?
- 14 posts at 8 ft spacing (13 sections plus one), or 18 at 6 ft. Add one post for each gate, and one for each corner if the run turns and the corner does not land on a post anyway.
- How deep should a fence post be?
- A third of the height above ground, and never less than 2 ft: 2 ft for a 6 ft fence, 2.7 ft for an 8 ft fence. In cold climates the hole must reach below the frost line, which can be 3 or 4 ft; check the local code. The hole is about three times the post width, 10 in for a 4x4.
- How many bags of concrete per fence post?
- 2 bags of 80 lb for a 4x4 in a 10 in hole 2 ft deep (1.01 cubic feet with 10% extra), so 28 bags for the 14 posts of a 100 ft fence. Fast-setting 50 lb bags work out at 3 per hole; the concrete per fence post guide has every hole size.
- How many pickets do I need for an 8 ft section?
- 16 pickets of 3 1/2 in with a 2 1/2 in gap, which is a 6 in pitch. Butted 5 1/2 in privacy boards need 18 per 8 ft section (17.5, and the half board is cut). Change the width and the gap in the form for any other layout.
- How many rails does a fence need?
- Two rails for fences up to 4 or 5 ft, three for 6 ft privacy fences so the boards do not cup and warp, and three or four for 8 ft. The form fills the usual number for each style and lets you change it.
- Should posts be 6 or 8 feet apart?
- 8 ft matches 16 ft rail lumber cut in two and 8 ft pre-built panels, and is the norm for a 6 ft privacy fence in sheltered ground. Use 6 ft for taller fences, heavy boards, windy sites or soft soil: more posts, more concrete, but a fence that stays straight.
Guides
- How many fence posts do I need? (50 to 300 ft)
Posts, sections and rails for 50 to 300 ft of fence at 6 and 8 ft spacing, what a gate or a corner adds, the bags of concrete for the holes, and 10 to 100 m in metric.
- How deep should a fence post be? (by fence height)
A third of the height in the ground, 2 ft minimum: depth, hole size, post length to buy and concrete bags per hole for 3 to 8 ft fences, and what the frost line changes.
- How many pickets for a fence? (per section and per 100 ft)
Pickets per 6 and 8 ft section and per 100 ft for 3 1/2 and 5 1/2 in boards at 0 to 3 1/2 in gaps, with waste, screws per picket, and the metric board counts.