Material Math Guide
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Fence Calculator: Sections, Posts, Rails, and Pickets

Estimate basic fence components for one straight run and up to one gate opening.

Enter every spacing and dimension from the selected system and local site requirements.

Enter the full straight fence run including the gate opening.

Enter one gate opening, or enter 0 when there is no gate.

Enter spacing from the selected system and site-specific requirements.

Enter the rail count required by the selected fence system.

Enter the actual face width of one picket.

Enter the planned clear gap between pickets.

Enter an allowance for cuts and rejected pieces.

Estimate boundary

What this result covers

  • Does not validate property lines, utilities, permits, wind loads, footings, grades, corners, or structural design.
  • Use the result as a purchasing estimate and verify product instructions, site conditions, and local requirements before work begins.

How the calculation works

Formula

sections = ceil(run ÷ post spacing); pickets = ceil((run − gate) × 12 ÷ (picket width + gap) × (1 + waste percentage))

Assumptions used

  • The estimate covers one straight run and at most one gate opening.

The tool keeps user-entered product values separate from the geometry, then rounds the recommended purchasing quantity up where the material is bought as a whole unit.

Worked example

Project inputs
100 ft run, one 4 ft gate, 8 ft spacing, 3 rails, 5.5 in pickets, 0.5 in gaps, 10% waste
Purchase result
13 sections, 15 posts, 39 rails, and 212 pickets.

Enter these values in the calculator to reproduce the estimate. The purchase result uses the same tested calculation logic as the live tool.

Purchasing checklist

  1. Confirm property lines and utilities.
  2. Check local rules and wind exposure.
  3. Verify the full product system.

Common mistakes

  • Using nominal instead of actual widths.
  • Ignoring gates.
  • Treating spacing as universal.

Sources and methodology

These references support the product values, units, or planning boundaries shown on this page. Always confirm the current instructions for the exact material you buy.

  1. Master Halco — PostMaster+ InstallationChecked 2026-07-11

    Post spacing varies with local conditions and wind exposure; method/product instructions matter.