Fence Calculator
Find out how many posts, rails, pickets or panels, and bags of concrete you need.
| Item | Amount |
|---|---|
| Rails | |
| Pickets | |
| Panels | |
| Concrete for the posts | |
| Post holes |
Shopping list
How the fence calculator works
The calculator takes your total length, subtracts the gates, and divides the rest by your post spacing to get the number of sections. A straight fence needs one more post than sections, and every gate adds a post. A closed loop needs one post per section.
- Rails: 2 per section up to 4 ft tall, 3 for 5 to 6 ft, and 4 for taller fences.
- Pickets: the fence length divided by picket width plus gap, plus your extra percentage.
- Concrete: the volume of each hole minus the post, with a 4 in gravel base at the bottom, divided by the bag yield (0.6 cubic feet for an 80 lb bag).
Worked example: 100 ft of 6 ft privacy fence with one 4 ft gate
The gate takes 4 ft, leaving 96 ft of fence, which is 12 sections at 8 ft spacing. That needs 14 posts: 13 for the straight run plus one for the gate. At 3 rails per section you need 36 rails. With 5.5 in pickets and 1/8 in gaps, 96 ft takes about 205 pickets, or 216 with 5% extra.
A 6 ft fence on 4x4 posts gets a 12 in wide, 36 in deep hole. With a 4 in gravel base, each hole takes about 1.9 cubic feet of concrete, or roughly 3 bags of 80 lb. For 14 posts that is 44 bags. Smaller holes use less concrete, and some builders use fast-setting mixes, so check what your supplier recommends.
Frequently asked questions
How many fence posts do I need?
Divide the fence length by the post spacing, round up for sections, and add one post for a straight run. Each gate adds one more post.
How far apart should fence posts be?
Eight feet is standard for wood and vinyl because it matches stock rail length and panel width. Wider than that, wood rails can sag over the years. Closer than 6 feet adds posts without adding much strength.
How deep should the post holes be?
A common guide is one third to one half of the above-ground height, with a hole about three times as wide as the post. A 6 ft fence typically gets a 36 inch hole. Local frost depth and building code can require deeper holes.
Do gates need special posts?
Gates wider than about 3.5 ft or taller than about 5 ft usually need a heavier hinge-side post, such as a 6x6. Follow your gate hardware instructions.
Estimates only. Call your utility locating service before you dig, and confirm height limits, setbacks and permits with your local authority.