DeckPlan Tools
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Deck Post Calculator

Estimate post count and stock purchases from user-supplied beam layout and spacing. Change any input to see an immediate, explainable estimate.

Project inputs

ft
ft
ft
ft
%
Add cutting and defect allowance; complex layouts often need more.

Plan preview

Interactive deck plan10 by 10 foot rectangle deck, length boards, showing boards view.10 ft10 ftSCALED TO FIT
Accessible summary: 0 ft long × 0 ft wide; standard layout. Drawing is for planning visualization, not construction details.

Your estimate

Updates live
Post positions8
Posts per beam run4
Total cut length24 ft
Stock posts4
Assumptions
  • 6 ft maximum proposed spacing
  • Independent run endpoints are not shared
Spacing is a user-supplied planning assumption, not a structural recommendation.

How to use this calculator

  1. Measure the project and enter the requested dimensions. Use actual product dimensions where the form asks for them.
  2. Replace the sample assumptions with the spacing, stock lengths, coverage, or prices that apply to your plan.
  3. Review the result, assumptions, and any limitation notice. Save the project locally or export a dated PDF for discussion.
Quantity estimate—not structural approval.

This calculator does not verify loads, spans, soil, frost depth, connections, product approvals, or local code. Use a qualified local professional for decisions that affect safety.

Calculation methodology

Each beam run receives posts at its endpoints and enough intermediate positions to keep segments within the user-entered spacing. Total cut length plus waste is converted to stock purchases.

Intermediate values retain decimal precision. Physical purchase units are rounded up only at the purchasing step, so the tool does not silently understate whole boards, bags, boxes, or containers.

Worked example

A 16 ft run at a proposed 6 ft maximum divides into three segments and therefore four posts per independent run.

Material and measurement considerations

  • Shared intersections can reduce duplicate posts in a detailed plan.
  • Actual cut length depends on footing and beam details.
  • Spacing is an assumption, not a recommendation.

Common mistakes

  • Counting spaces instead of posts.
  • Assuming every run shares endpoints.
  • Choosing spacing with this quantity calculator.

Frequently asked questions

Is the entered spacing safe?

The tool does not assess safety. A qualified designer must verify loads, beam capacity, footings, bracing, and connections.

Sources and limitations

The estimator uses your measurements, standard geometry, unit conversion, and product data you enter. Product coverage, gaps, fastening, and installation details should come from the current manufacturer documentation for the exact material. Structural and permit requirements must be confirmed for the project location. No live price feed, fabricated standard, or universal structural rule is used.