About This Calculator
What We Do
DeckingCalc is a free online tool that helps homeowners, DIY enthusiasts, and tradespeople estimate the materials needed for garden decking projects. Enter your deck dimensions, choose your board material and layout pattern, and receive an itemised shopping list with estimated costs — all in seconds, with no sign-up required.
How Calculations Work
Our calculator uses standard UK board dimensions, joist spacings, and fixing rates derived from manufacturer specifications and industry guidelines. Board counts are calculated row-by-row using actual board widths plus gap spacing, then adjusted for waste based on layout pattern (10% standard, 15% diagonal, 20% herringbone). Joist quantities use centre-to-centre spacing with an additional end joist. Bearer and post counts are based on maximum recommended spans for domestic loading.
Pricing Data
Cost estimates are based on typical UK supplier pricing as of early 2025, averaged across major national retailers and independent timber merchants. Prices are per linear metre for boards and joists, and per unit for fixings and posts. Actual prices vary significantly by region, supplier, stock availability, and whether you purchase individual items or bulk packs. Always confirm current prices with your chosen supplier before purchasing.
Privacy
Every calculation runs entirely in your web browser. We never store your project dimensions, costs, or personal details on any server. When you save your inputs, they are stored in your browser's localStorage — a storage mechanism that keeps data on your device only. Clearing your browser data removes all saved calculations. We use Google Analytics to understand how people use the site (page views, not personal data) and Google AdSense to support the free service, both subject to your consent preferences.
Limitations
This calculator provides estimates for planning purposes only. It does not account for site-specific conditions such as sloping ground, obstacles, drainage requirements, or access restrictions. The structural calculations assume standard domestic loading — if you are planning a hot tub platform, commercial decking, or any structure that will bear unusual loads, consult a structural engineer.
Disclaimer
DeckingCalc provides free estimation tools for informational purposes only. We do not provide professional advice, building services, or material supply. All results are approximate and should be verified independently before purchasing materials or beginning construction. We accept no liability for any losses arising from reliance on calculator outputs. Always consult qualified professionals for structural work, raised decks, or any project you are uncertain about.