Fence Calculator
Estimate fence posts, rails, pickets and concrete for post holes along a straight fence run. Adjust post spacing, picket width, gap, rail rows, waste and optional US-dollar material prices.
Your fence material estimate will appear here.
How to estimate fence materials
This estimator models one straight fence run with evenly spaced posts, horizontal rails and vertical pickets. It calculates the number of post positions, fence bays, rail pieces, pickets and concrete bags for identical cylindrical post holes.
Fence material formulas
Post count = round up (fence length ÷ post spacing) + 1
Fence bays = post count − 1
Rail count = bays × rails per bay
Picket count = round up [fence length × 12 ÷ (picket width + gap)], before adding the waste allowance.
Concrete per post hole = π × (hole diameter ÷ 24)² × (hole depth ÷ 12), in cubic feet. Total concrete is that volume multiplied by post count; bag quantity is rounded up using the yield entered.
Worked example
For a 100-foot straight fence with posts every 8 feet, the simple estimate is round up (100 ÷ 8) + 1 = 14 posts and 13 bays. With 3 rails per bay, it estimates 39 rails. Picket quantity depends on actual picket face width and spacing gap.
Important assumptions
- This estimate assumes one straight run. Corners, gate openings, end conditions, stepped terrain and transitions need separate layout adjustments.
- It counts one post at each end and evenly spaced intermediate posts. Actual spacing must follow fence height, wind exposure, material and local requirements.
- Post-hole concrete uses identical cylindrical holes and estimates the full hole volume without subtracting the post’s displaced volume, so the bag count is a conservative planning estimate. Actual holes and concrete placement may differ.
- Each rail count represents one rail section per bay. Rail stock length, picket length, post size, fasteners, caps, hardware, gravel drainage and gate materials are not fully designed or optimized by this estimate.
Frequently asked questions
How many posts do I need for a 100-foot fence?
At 8-foot maximum spacing on a straight run, the basic estimate is 14 posts. The actual layout may use closer spacing at corners or for different terrain.
How many rails should a fence have?
Rail count depends on fence height, construction type and design. Enter the number specified by your plans or product instructions.
Does this calculate gates?
No. Gate openings and their reinforced posts should be measured and estimated separately.
Related estimators: Deck Material Calculator · Gravel Calculator · Concrete Slab Calculator.
This is a preliminary materials take-off, not a structural design. Confirm post depth, spacing, concrete requirements, property boundaries and local fence rules before installation.