Decking Calculator
Calculate how many decking boards you need for a new deck. Enter your deck dimensions, board size, spacing and stock length to get a practical buying estimate.
Typical use: Timber & composite decking boards, expansion spacing, stock lengths & pack quantities
Using this calculator
Open the interactive calculator to enter your project measurements and adjust the available settings. Review the calculated quantity and buying units before ordering materials. Check product coverage, pack sizes and installation guidance with the manufacturer or supplier.
Planning and practical guidance
Decking Basics: Planning, Joists, Board Gaps & Fixing
Plan a straightforward garden deck while keeping joist spacing, board gaps, ventilation, drainage and manufacturer instructions in view.
- Decide whether the deck is ground-level, raised or attached to a building, because height, structure, guarding, access and planning/building requirements can change substantially between these arrangements.
- Check the ground, drainage and finished level before building the frame. Avoid creating a deck that traps water against the house, blocks air bricks or raises the finished surface inappropriately near damp-proof courses.
- Use timber grades, supports and structural details suitable for the span and loading. Get Your Project Right’s material estimate does not design a load-bearing deck frame.
- Follow the chosen board manufacturer’s maximum joist spacing. Different timber and composite board profiles can require different centres, and angled board layouts often need closer support.