Work out how much material to buy before you start. Each calculator shows its formula, a worked example and the limits of the estimate, so you can check the numbers for yourself.
- 10 free calculators
- Imperial + metric on every tool
- Formula and worked example on every page
Roofing
Roof Pitch CalculatorTurn rise and run into a ratio, slope percentage and angle.Roof Area CalculatorRoof surface area and roofing squares from your house size and pitch.
Rooms and finishes
Paint CalculatorGallons or litres of paint for a room, with coats and waste.Flooring CalculatorHow many boxes of flooring to buy, with a waste allowance.Square Footage CalculatorAdd up the area of up to six rooms in sq ft, m² and sq yd.Baseboard and Quarter Round CalculatorPieces of trim to buy, after taking off the door openings.Rug Size CalculatorThe largest standard rug that fits your room with a clear border.
Outdoors
Mulch CalculatorCubic yards and bags of mulch for a garden bed.Concrete CalculatorConcrete volume and bags for a slab, with waste.
Energy
Before you start
Measure twiceUse the same unit for every number, or switch the units menu on the tool.
Check the labelCoverage, bag size and box size come from your product, so enter those from the packaging.
Round upMaterials are sold whole, so every tool rounds up to the next box, bag or piece.
These results are estimates for planning. Local rules, product differences and site conditions can change what you need, so check with the manufacturer and ask a professional before work that affects structure or safety.