How Many Fence Posts for 100 Feet?
At 8-foot maximum spacing, a straight 100-foot fence needs 14 regularly spaced posts before any additional gate, corner or terminal posts.
100 feet with 8-foot maximum spacing
Divide fence length by the maximum post spacing, round the number of spaces up, then add one post because a row of spaces always has one more boundary post than spaces.
spaces = ceiling(100 / 8) = 13
posts = 13 + 1 = 14
The actual spacing after rounding is about 7.69 feet, keeping every section within the 8-foot maximum used in the example.
What if posts are spaced 6 feet apart?
ceiling(100 / 6) = 17 spaces
17 + 1 = 18 posts
Closer spacing increases post count, and it can also change rail or panel planning.
Why gates and corners can add posts
A gate opening, change of direction or terminal assembly can split one continuous run into separate fence sections. Those sections may require their own end or structural posts beyond the simple spacing count.
For irregular layouts, estimate each straight run separately, then add the known extra gate and corner posts from the plan.
Panels, pickets and rails are separate quantities
Post spacing alone does not determine the complete material list. Prefabricated panels have their own width, pickets depend on picket width and gap, and rails depend on both run length and the number of rail rows.
Use the Fence Calculator for length, post spacing, gates, panels or pickets, rail rows and optional material cost.
Spacing is a layout input, not a universal recommendation
The arithmetic in this guide assumes a chosen post spacing and a measured fence run. The correct spacing can change with fence style, panel width, wind exposure, gate locations, terrain and the structural requirements of the selected system.
When planning a real fence, mark end posts, corners and gate posts first. Then divide the remaining straight runs using the spacing specified by the fence manufacturer, project plan or applicable local requirement. If a final run is shorter than the nominal spacing, keep that shorter bay rather than stretching every bay beyond the intended layout just to make the numbers divide evenly.
Why two separate fence runs may need more end posts
A single continuous straight run of 100 ft at an 8 ft maximum spacing requires ceiling(100 ÷ 8) + 1 = 14 posts. Compare that with two disconnected runs of 50 ft each: each run requires ceiling(50 ÷ 8) + 1 = 8 posts, or 16 posts total. The extra posts are due to the separate end conditions, not a different spacing rule.
If the two runs meet at one shared corner or are separated by a gate, the correct post count depends on which terminal, gate and corner posts are structurally shared. Mark those locations on a sketch and calculate each run from its actual endpoints; do not blindly add a second end post at a shared corner. This remains material-planning arithmetic, not a recommended post spacing for a particular fence design.
Worked corner layout: count the shared post once
Suppose a homeowner measures an L-shaped fence with a 36 ft side and a 28 ft side. Both straight sections use an illustrative maximum spacing of 8 ft. The first section needs ceiling(36 ÷ 8) = 5 bays, so it has 6 post positions. The second needs ceiling(28 ÷ 8) = 4 bays, so it has 5 positions. If the two runs meet at one usable structural corner post, count that common post only once: 6 + 5 − 1 = 10 unique post positions.
| Run | Length | Bays at maximum 8 ft | Positions including both ends |
|---|---|---|---|
| Side A | 36 ft | 5 | 6 |
| Side B | 28 ft | 4 | 5 |
| Shared-corner total | 64 ft of fencing | 9 bays | 10 unique posts |
The estimated bay lengths are 36 ÷ 5 = 7.2 ft and 28 ÷ 4 = 7 ft. Dividing the combined 64 ft by 8 ft and adding one would give 9 posts, but that treats the L as one straight line and loses the corner position. Draw the actual turns first. If the corner needs a special assembly with more than one physical post, use the manufacturer's plan rather than the shared-post assumption.
Gate example: the opening is not a normal fence panel
Now imagine two separate 35 ft straight fence runs with a 4 ft gate opening between them. The overall distance from one outer end to the other is 35 + 4 + 35 = 74 ft, but the 4 ft opening is not part of either run's ordinary fence bays. Each 35 ft run needs ceiling(35 ÷ 8) + 1 = 6 positions, for a preliminary total of 12 posts across the two runs.
This total assumes the posts at the inner ends are also the gate-support posts, counted once. Do not add another automatic pair simply because a gate is present, and do not use the continuous-run count of ceiling(74 ÷ 8) + 1 = 11. Either shortcut hides the physical layout. Real gate posts may need different sizes, footing details, hardware clearances and reinforcement; a heavy or wide gate can change the assembly. Confirm the gate manufacturer's required clear opening, actual post-center measurements and local requirements before purchasing.
A marking and purchasing checklist for a homeowner
- Walk the property, confirm the actual boundary and permitted fence location, and sketch every straight run with its measured length.
- Mark corners, free ends, gates, transitions and other structural positions before dividing any run into bays.
- Choose the allowable post spacing from the specific fence system and project requirements. An 8 ft assumption in an example is not a universal installation specification.
- For each run, round the bay count up; then combine endpoint lists and remove only genuinely shared physical posts.
- Separate ordinary line posts from gate and corner assemblies in the shopping list. Posts, rails, panels, pickets, fasteners and concrete are different quantities.
- Measure again after staking positions. Slopes, obstructions and actual panel dimensions may require a different layout.
The Fence Calculator helps estimate material counts and optional costs from your chosen layout. For the measuring workflow, see How to Measure for Building Materials. These calculations are a starting quantity estimate—not a structural design, a property-line survey or permission to build.
Fixed fence panels require a different layout check
For a build with adjustable rails and individual pickets, a maximum allowable bay length can be a useful planning input. Prebuilt panels are different: the manufacturer may specify the exact post center-to-center distance, panel body width or bracket allowances. Thirteen equally distributed spaces along 100 feet measure about 7.69 feet each, but that does not prove thirteen nominal 8-foot panels will fit without modification. Never stretch spacing beyond the panel or wind-load design to make the material count look neat.
Before shopping, draw the actual property line and label every corner, gate opening, end and change in elevation. Measure each straight segment separately, and confirm whether supplier dimensions refer to the clear opening, panel edge-to-edge or post centerline. Also check setbacks, underground utilities, local permits and boundary requirements where they apply; this guide calculates quantities, not the legality or structural adequacy of a fence.
Use the Wood Fence Calculator to estimate posts, rails or pickets from the verified dimensions, then move actual supplier prices into your Project Budget Workspace. Keep the gate hardware, concrete, finish materials, delivery and any professional work as separate line items rather than assuming they are included in a post-count estimate.