Fence Calculator
Enter your fence line length to get posts, pickets and rails for a wood fence.
Enter your measurements to see what to buy.
How to calculate it
Enter your fence line length to get posts, pickets and rails for a wood fence.
Source: Sections = length ÷ post spacing; posts = sections + 1. Picket count = length in inches ÷ (picket width + gap).
A 50 ft fence, 8 ft post spacing, 5.5 in pickets, 0.5 in gaps, 3 rails: 7 sections → 8 posts; pickets = (50×12) ÷ 6 = 100 pickets; 21 rails.
Want the full step-by-step walkthrough? Read our How to Calculate Shingles for a Roof.
How to use this calculator
- Enter the total fence line length in feet and inches.
- Set the post spacing (8 ft is standard), picket width, gap, and number of rails per section.
- The calculator returns posts, pickets and rails for a single straight run.
- Add posts manually for each corner, end and gate, and enter prices for a cost estimate.
Purchasing & waste guidance
- 8 ft post spacing is standard; 6 ft is stronger in high-wind areas.
- Set posts in concrete — about one 50 lb bag per post for a 6 ft fence.
- Use 0.5 in gaps for a spaced picket look, or 0 in (butted) for full privacy.
- Two rails work up to 5 ft tall; use three rails for 6 ft and taller fences.
- Check property lines, permits and call 811 before digging post holes.
Waste factor guidance
- 10% covers cuts and culls for pickets on a straight run.
- Use 15% for fences following a slope or with many corners.
- Order posts exactly — extras are only needed for the corners, ends and gates you add by hand.
Common mistakes to avoid
- Forgetting to add posts for corners, ends and gates — the calculator counts a straight run only.
- Spacing posts too wide (over 8 ft) so rails sag under wind and weight.
- Skipping the 811 utility locate before digging post holes.
Assumptions & what’s included
- Fence is a single straight run; post spacing is uniform.
- Picket count uses nominal width plus gap; rails = rails per section × sections.
- Prices are per picket and per post and optional. Gate hardware is extra.
Frequently asked questions
How many fence posts do I need for 100 feet?
At 8 ft spacing, 100 ft of fence has 13 sections and needs 14 posts (sections + 1). Use 6 ft spacing in high-wind areas for a stronger fence.
How many pickets do I need for a 50 ft fence?
With 5.5 in pickets and 0.5 in gaps, a 50 ft fence needs about 100 pickets. Butted pickets (no gap) need about 109.
How much concrete do I need for fence posts?
About one 50 lb bag of concrete per post for a 6 ft fence. Use the Concrete Bag Calculator to total it up for the whole fence line.
How many rails do I need for a 6 ft fence?
Use three rails for a 6 ft fence — two rails are fine up to about 5 ft. Multiply rails per section by the number of sections to get your total rail count.
Related guides
Step-by-step project guides that use this calculator.