Fence Post Calculator for Garden Projects

• Effective fenced length = Total length − (Gate count × Gate width).
• Number of spans = ceil(Effective length ÷ Target spacing).
• Adjusted spacing = Effective length ÷ Number of spans.
• Line posts (straight run) = max(0, spans − 1).
• Total posts (straight run) = Line posts + End posts + Corner posts + Gate posts.
• Total posts with waste = ceil(Total posts × (1 + Waste%)).
• Concrete volume = Posts × π × (d/2)² × depth × (1 + Overfill%).
• Bag count = ceil(Total concrete volume ÷ Bag yield).

Planning Fence Runs With Accurate Spacing

Consistent post spacing improves strength and keeps rails or wire straight. The calculator converts your length into spans using a ceiling rule, so each gap stays at or below the target. Use the adjusted spacing result as your center‑to‑center marking distance. Typical garden runs use 2–3 m spacing, or 6–8 ft. Mark with a tape, set temporary stakes, then confirm the final post positions before digging.

Handling Corners, Ends, and Gate Openings

Corner and terminal posts resist higher loads than line posts. Enter corner posts for every direction change and end posts for open runs. Gate openings reduce fenced length, so total gate width is removed before span spacing. Gate posts are added separately because they support hinges, latches, and bracing. Braced corners often need one brace set per corner post.

Waste Allowance and Post Purchasing Strategy

A waste allowance prevents delays when posts are bowed, cracked, or cut wrong. The tool applies your percentage, rounds up, and returns a practical purchase quantity. Use 5% for consistent materials and easy access. Use 8–12% for rocky soil, long transport, or multiple corners where mistakes cost time. Save the same waste rate in exports to standardize ordering.

Concrete Volume and Bag Estimation

Concrete planning depends on hole diameter, depth, and overfill. When hole sizes are provided, each hole is treated as a cylinder and multiplied by total holes. Overfill covers bell‑shaped digging, gravel bedding, and spillage during tamping. For many posts, small diameter changes shift volume quickly. If your bag lists yield in liters or cubic feet, enter it to estimate bags.

Interpreting Outputs for Fast On‑Site Layout

Use total posts including waste for ordering. Use the breakdown to assign heavy‑duty hardware to corners and gates. Spans indicate how many equal intervals to mark along the run. Perimeter mode assumes spacing wraps evenly around a loop; remeasure each side so the interval does not crowd a corner. Export CSV for purchasing, and PDF for site records.

1) Why does the calculator adjust my spacing?

It uses a ceiling span count so no gap exceeds your target. The adjusted spacing divides the effective fenced length evenly across all spans, creating a cleaner layout and consistent panel alignment.

2) What is “effective length” and why does it matter?

Effective length is total fence length minus gate openings. Spacing is based on the length that actually receives posts, so your marks don’t drift when gates are included.

3) When should I choose the perimeter option?

Choose perimeter for a closed loop around a bed or yard boundary. It assumes spacing wraps evenly around the loop and removes end posts because the fence reconnects.

4) How much waste allowance is reasonable?

Common allowances are 5–10%. Use the low end for uniform materials and easy digging. Increase it for rocky soil, steep slopes, long deliveries, or mixed post lengths.

5) How accurate is the concrete estimate?

It’s a planning estimate using cylindrical holes and your overfill percentage. Real volume changes with soil conditions, bell holes, and gravel. Use overfill to match your field experience.

6) Can I mix feet and meters in one calculation?

Keep length and spacing in the same unit to avoid scaling errors. Hole sizes can use centimeters or inches independently, since they convert to meters internally for volume.