How to Use This Calculator
Enter your fence length and try different post spacing values. This calculator shows how changing spacing from 6 to 8 to 10 feet affects your total post count, rail material, and concrete cost. Use it to compare the tradeoff between fewer posts (cost savings) and closer spacing (structural strength).
Set rails per section to 3 for a 6-foot privacy fence. Adjust picket width and gap for your fence style. Hit Calculate to see the full material list. Try the spacing presets to see how the numbers change side by side.
How to Calculate Fence Post Spacing
The post spacing formula is: Posts = ceil(Fence Length / Post Spacing) + 1.
The "+ 1" accounts for the final end post. For a straight run from point A to B, you need one post at the start and one at the end, plus one at each intermediate interval.
Example: 97-foot fence at 8-foot spacing.
- 97 / 8 = 12.1 sections, rounded up to 13
- Posts = 13 + 1 = 14 posts
For uniform spacing on a non-round fence length: divide fence length by the post count minus 1. For 14 posts on a 97-foot fence: 97 / 13 = 7.46 feet per section. Set each post at 7.46-foot intervals for a clean, uniform look from the street.
Rail linear feet = Fence Length x Number of Rails. Concrete bags = Posts x 2 (two 60-lb bags per post).
Post Spacing Tips
Measure and mark all post locations before digging. Stretch a string line from corner to corner at grade level. Mark each post location with a stake. Double-check spacing by measuring from stake to stake. It is much easier to adjust a stake than to fill and re-dig a post hole in the wrong spot.
Start from a corner post and space out uniformly. Do not let the last section be a short stub at a gate or property edge. Calculate uniform spacing that divides the fence length evenly into sections. A 4-foot stub section at the end of a fence looks unfinished and is harder to gate.
Check local building codes before setting posts. Most jurisdictions require permits for fences over 6 feet tall. Some areas limit front-yard fence height to 4 feet. HOAs may restrict post spacing, materials, or colors. Check all rules before buying materials to avoid required changes after installation.
What to Buy
Posts: 4x4 pressure-treated ground-contact posts (UC4B rating). Length depends on fence height plus in-ground depth. For a 6-foot fence, buy 9-foot or 10-foot posts and set 3 feet in the ground.
Rail hardware: post rail brackets are faster than toe-nailing. Galvanized post-to-rail brackets sold at hardware stores hold 2x4 rails without splitting. Use 2 brackets per rail end per post for a secure connection.
Post hole digger: rent a gas-powered one-person auger for projects under 20 posts. Rent a two-person towable auger for larger projects. A clamshell post digger works for 10 posts or fewer in soft soil. Auger diameter: 8 inches for a 4x4 post, 12 inches for a 6x6 post.
Concrete: Quikrete Fast-Setting 60-lb bags, 2 per post. Pour dry into the water-soaked hole and add water on top. No mixing needed. Sets in 20 to 40 minutes so you can move to the next post quickly.