About SpadeMath

SpadeMath is a small, independent website that helps homeowners and DIYers work out how much material to buy for landscaping and home projects: gravel, river rock, paver base and sand, concrete block, tile and wallpaper.

How we build our calculators

• Show the formula. Every calculator page explains the math it uses and includes a worked example you can check by hand.
• Name our assumptions. Material densities and coverage figures are listed on each page with where they come from, such as The Engineering ToolBox density tables or manufacturer data sheets. Where suppliers vary, we say so and let you enter your own figure.
• Test the math. Each calculator is checked against hand-calculated examples before it is published, and re-checked when we change it.
• Keep it fast and private. The calculators run in your browser. We do not require an account.

Limitations

Our results are planning estimates. Real-world quantities depend on your site, the exact product, moisture, compaction and installation method. Always confirm with your supplier, and follow manufacturer instructions and local building codes. For structural work, consult a qualified professional.

Feedback

Found an error or want a new calculator? Please contact us. Corrections are our top priority.