Construction Calculators
From concrete and flooring to roofing and paint — our free construction calculators estimate material quantities and costs so you can quote accurately and order the right amount.
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Foundations & Concrete
Concrete volume, rebar, and foundation calculations
Flooring & Walls
Flooring area, tiles, paint, and wallpaper
Roofing & Structure
Roofing materials, lumber, and structural estimates
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Construction Glossary — Key Terms Explained
- Square Footage / Square Metres
- The area of a surface measured in square feet (US) or square metres (UK/EU). For a rectangular room: length × width. For irregular shapes, divide into rectangles and sum the areas.
- Cubic Yards / Cubic Metres
- Volume measurement used for concrete, fill material, and excavation. 1 cubic yard ≈ 0.765 cubic metres. A standard ready-mix truck delivers 8–10 cubic yards.
- Wastage Factor
- Extra material ordered to account for cuts, defects, and errors. Standard flooring and tiling adds 10–15% waste. For diagonal tile patterns or complex layouts, add 15–20%. Always order slightly more than calculated.
- Board Foot (US)
- A unit of lumber volume: 1 board foot = 1 foot × 1 foot × 1 inch thick. Used to price and estimate lumber quantities. 144 cubic inches = 1 board foot.
- Compressive Strength (PSI / MPa)
- Concrete strength measurement. Standard residential concrete: 3,000 PSI (20 MPa). Driveways: 4,000 PSI. Structural applications: 4,000–5,000 PSI. Higher PSI = stronger but more expensive.
Frequently Asked Questions
How do I calculate how much concrete I need?
Volume (cubic metres) = Length × Width × Depth. For a 4m × 3m × 0.1m slab: 4 × 3 × 0.1 = 1.2 cubic metres. Add 10% for waste and over-pour: 1.32 cubic metres. One standard ready-mix lorry (UK) delivers around 6–8 cubic metres — for small pours, consider bagged concrete.
How many tiles do I need for my bathroom?
Calculate the total wall and floor area in square metres. Add 10% for waste (15% for diagonal layouts). Divide by the tile area to get the number of tiles. Example: 15 m² of wall ÷ 0.09 m² per tile (30×30cm) = 167 tiles + 10% = 184 tiles.
How many litres of paint do I need?
Standard coverage: 10–12 m² per litre for walls, 8–10 m² for ceilings, 14–16 m² for woodwork. For a 4m × 3m room with 2.4m ceiling: wall area ≈ 2 coats × (2 × (4+3) × 2.4) = 67.2 m². At 10 m² per litre: 6.7 litres per coat. Budget 14 litres for two coats.
How much extra flooring should I order?
Add 10% waste for straight-lay flooring in a regular rectangular room. Add 15% for diagonal layouts, herringbone patterns, or rooms with alcoves and awkward shapes. For natural materials (wood, stone) where pieces vary significantly, consider 12–15% waste minimum.