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Building Projects Calculators

Concrete, decking, fencing and brick calculators for the structural jobs, with the fasteners and mortar counted too. Building projects fail on the invisible items — the screws, the post mix, the last bag of mortar — so each calculator here counts the companions as well as the headline material.

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How these calculators work

Every calculator on this page follows the same honest pattern: measure the real space, convert with the standard formula for that material, and add a waste allowance for cuts, breakage and real-world imperfection. Each calculator page shows its formula and a worked example, so you can check the maths by hand before you spend anything. If your own product states different coverage on its label, that label wins — the pages explain how to scale the result.

New to the material? Read the linked guides as well as the calculator. The guides cover the judgement calls a calculator cannot make — layout choices, depths, thicknesses and the local rules worth checking before you start.

Planning notes

A note on building work: quantities are only half the plan. Check local rules for fence heights, deck footings and concrete work before ordering, stage materials so the first-needed items come off the pile first, and never let a calculated quantity talk you out of one spare board, panel or bag — the spare is the cheapest insurance on the whole job.

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