About & Calculation Methods

How the estimate works

For each rectangular area, multiply length by width, then multiply by depth in feet. A square uses side length × side length. An oval uses length × width × π ÷ 4. A circle uses π × radius². Add the volumes of all areas, then apply the extra-material percentage once.

There are 27 cubic feet in one cubic yard. Bag quantities round up to whole bags. Bulk orders round up to the increment you enter, after applying your supplier’s minimum order. Taxes, installation, pickup costs and additional fees are excluded.

Weight, blends and pricing

Gravel weight uses the density entered by the user. US tons divide pounds by 2,000. A soil blend splits the required new volume according to the entered compost percentage. Bulk prices are based on the rounded order, not just the theoretical volume.

All prefilled prices, densities and allowances are examples. We do not collect live retailer prices or endorse a supplier. We do not claim professional engineering or horticultural review. Planting guidance is linked to its source where used.

Corrections and limitations

Our calculators run locally in your browser. We check formulas against worked examples, including purchase rounding. Measurements, supplier specifications and project requirements still need your verification. Report a suspected error with the calculator name, inputs and expected result.