About ShovelMath
ShovelMath is a set of 64 free calculators for estimating bulk materials — gravel, mulch, soil, sand, stone, limestone, sod, asphalt, roofing, shingles, metal roofing, siding, gutters, pavers, brick, block, tile, decking, flooring, lumber and epoxy. Everything runs in your browser: no signup, no data collection, no uploaded measurements.
Methodology
Every calculator uses the same transparent approach:
- Geometry first. Your measurements are converted into a volume or area — for loose materials,
length × width × depth, converted to cubic yards (27 cubic feet each), the unit bulk suppliers sell in. - Published densities. Weight conversions use standard material densities (e.g. compacted hot mix asphalt at 145 lb/ft³, dry sand at 100 lb/ft³, river rock at 94 lb/ft³). These match the reference values used by aggregate suppliers; actual loads vary a few percent with moisture and stone size, which is why every page shows its density table openly.
- Honest waste factors. Each calculator adds an industry-typical allowance — 5–10% for settling, cuts and spillage — and always shows both the exact and the padded figure, so you decide what to order.
- The formula on the page. Every calculator prints its formula so you can check the math by hand or reproduce it in a spreadsheet.
What these estimates are (and aren't)
These are planning estimates for homeowners and DIYers: good enough to compare quotes, size a delivery and budget a project. They are not engineering documents. For structural work — retaining walls over 3 ft, driveways bearing heavy vehicles, anything with a permit attached — confirm quantities and specifications with your contractor or engineer.
Corrections
Spotted a density that doesn't match your supplier's spec sheet, or a formula you disagree with? We'd rather fix it than be defended — the whole point of the site is numbers you can trust. Write to kim@ryddigrebell.com, point at the page you mean, and say what your source says instead. Corrections get published, not argued about.
How the site is funded
ShovelMath is free and always will be. It is paid for by advertising and, on some pages, by commercial links to services a visitor might want after working out a quantity. Those links are labelled where they appear and never influence a formula, a density figure or a waste factor — the calculators are written first and the links go around them, not the other way round. The full rules are on the affiliate disclosure page.