About Green Tools

Green Tools makes free, fast calculators for home improvement and contracting projects. Whether you're a homeowner pouring your first patio or a pro writing a quick estimate, our tools tell you exactly how much material to buy and roughly what it will cost.

How our calculators work

Each calculator uses the standard formulas and coverage figures used in the trades, such as bag yields for concrete, coverage per gallon for paint and bundles per square for shingles. We include typical waste allowances and explain the math on every page, so you can check it yourself.

Free to use

There's no sign-up and nothing to install. The site is supported by ads and by links to stores where you can buy materials, as well as donations from people who find it useful.

Results are estimates for planning purposes. Always confirm measurements and follow local building codes.