Decking Calculator - Estimate Boards, Joists & Materials

Accurately calculate all materials for your deck project: decking boards, joists, bearers, stumps, and screws. Get instant estimates with wastage included.

Full original guide (expanded)

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted text)

$N_{boards} = \lceil \frac{DeckLength_{total\_inches}}{BoardWidth_{inches} + BoardGap_{inches}} \rceil$

Formula (extracted text)

$L_{decking} = N_{boards} \times DeckWidth_{feet} \times (1 + \frac{Wastage \%}{100})$

Formula (extracted text)

$N_{joists} = \lceil \frac{DeckLength_{total\_inches}}{JoistSpacing_{inches}} \rceil + 1$

Formula (extracted text)

$L_{joists} = N_{joists} \times DeckWidth_{feet}$

Formula (extracted text)

$N_{screws} = N_{boards} \times N_{joists} \times 2$

Variables and units

No variables provided in audit spec.

Sources (authoritative):

Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/
Construction — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/construction-diy
Materials Estimation — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/construction-diy-materials-estimation
official IRC source — codes.iccsafe.org · Accessed 2026-01-19
https://codes.iccsafe.org/content/IRC2021P2
Concrete Slab Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/concrete-calculator
Roof Rafter Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/rafter
Paint Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/paint-calculator
Fence Materials Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/fence-calculator

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
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Why Use This Calculator

Get a complete materials list, not just decking.
Includes substructure: joists, bearers, and stumps.
Instantly calculate the impact of different spacings.
Accounts for board gaps and critical wastage factor.
Mobile-first design for use on-site.

Related Construction Tools

Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft

Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog

0.1.0-draft — 2026-01-19: Initial draft (review required).