Outdoor & Decking Calculators
Calculate decking boards, joist spacing, pergola dimensions, fence panels, and outdoor furniture for garden projects.
Decking Board Calculator
Calculate the number of decking boards, screws, and joist hangers needed.
Deck Joist Calculator
Work out joist sizes, spacing, and quantities for a deck subframe.
Pergola Calculator
Calculate timber quantities for pergola posts, beams, and rafters.
Fence Panel Calculator
Work out fence panel, post, and gravel board quantities for a boundary.
Garden Bench Calculator
Calculate timber quantities and dimensions for a garden bench build.
Planter Box Calculator
Work out timber and liner quantities for raised planter box construction.
Gate Calculator
Calculate timber and hardware for garden and driveway gate construction.
Outdoor Table Calculator
Calculate material quantities for outdoor table and bench sets.
Post Foundation Calculator
Determine post hole depth, concrete quantities, and post sizes.
Timber Treatment Calculator
Calculate preservative and treatment quantities for outdoor timber.
10 free calculators in Outdoor & Decking
Outdoor and Decking Calculations
Outdoor timber projects require careful material calculation to keep costs under control. Decking, fencing, pergolas, and garden furniture all need treated timber that withstands the UK climate, and buying the right quantities avoids wasteful return trips to the merchant.
Decking is one of the most popular UK garden projects. Standard decking boards are typically 150mm wide (covering 145mm with a 5mm gap) and come in lengths of 2.4m, 3.0m, 3.6m, and 4.8m. Our decking board calculator works out the number of boards, screws, and joist hangers for your deck area.
The subframe is critical for a long-lasting deck. Joists are typically 47 × 150mm (or 47 × 200mm for longer spans) at 400mm centres. Our deck joist calculator sizes joists for your span and calculates all the framing timber needed.
Fence posts need solid foundations. In the UK, posts are typically set 600mm into the ground in concrete (postcrete or ready-mix). Our post foundation calculator determines hole depth, concrete quantities, and appropriate post sizes for your fence or pergola.