Free home project calculators
Know exactly what to buy before your project starts.
Enter your measurements and get the gallons, boxes, bags, sheets or bundles you need, with the formula shown step by step. Paint, flooring, concrete, mulch, decks, roofing and more, in US units.
- Formula and worked example in every guide
- Sources linked in every guide
- Free, no sign-up
Common projects
Jump straight to a calculator. Each one sits inside a guide that shows how to measure and how the math works.
- Concrete calculator Cubic yards and 60 or 80 lb bags for a slab, patio or walkway.
- Paint calculator Gallons for walls and ceilings, with doors and windows subtracted.
- Mulch calculator Cubic yards and bags for any bed size and depth.
- Square footage calculator Add up rooms and odd shapes in sq ft, sq yd and square meters.
All calculators
20 calculators in 6 categories. Pick your project to open the calculator and its step-by-step guide.
How our calculators work
- Measure Each guide shows what to measure and how, so the numbers you enter match what the formula expects.
- Calculate The calculator uses the same formula printed in the guide, with a worked example you can check by hand.
- Buy Results round up to whole gallons, boxes, bags or bundles, with extra for cuts and waste where the material needs it.
Coverage rates, bag yields, standard sizes and code limits come from manufacturer data sheets, the International Residential Code, ENERGY STAR and university extension services, and each guide links to the sources it uses. Our results are estimates for planning and buying materials. For structural work such as stairs, decks, roofs and block walls, check your local building code and work with a licensed pro.
About BuildCalc
BuildCalc is a free collection of home project calculators for US homeowners and DIYers. Read how we build and check our calculators on the About page, and contact us if a result ever looks off.