How we calculate
Every calculator on this site shows its working. This page lists the constants and assumptions behind them.
Exact unit conversions
We use the exact international definitions: 1 foot = 0.3048 m, 1 cubic yard = 27 cubic feet = 0.764554858 m³, 1 US ton = 2,000 lbs = 907.18474 kg. Results are rounded only for display.
Material weights
Where a result depends on how heavy a material is, the calculator shows the figure it uses and lets you change it. Bulk materials vary with type, grading and moisture, so the default is a starting point. Your supplier's figure for the exact material you are buying is always better.
Waste allowance
Calculators add an adjustable allowance (10% by default) for spillage, settling, compaction and uneven ground. Results are shown with and without it.
Prices
Prices vary by region and change often. Where a calculator estimates cost, you enter your own local price; we only pre-fill a price when we can cite a public source for it.
Product figures and their sources
| Figure | Used in | Source |
|---|---|---|
| Premix concrete yield: 40 lb = 0.30 cu ft, 60 lb = 0.45 cu ft, 80 lb = 0.60 cu ft | Concrete | QUIKRETE Concrete Mix data sheet |
| Most asphalt shingles: 3 bundles per 100 sq ft square; add 10–15% waste | Roofing | GAF |
| Interior paint coverage, e.g. 250–400 sq ft per gallon | Paint | Behr |
| Mulch depth of 2–3 in on plant beds | Mulch | UF/IFAS Florida-Friendly Landscaping |
Sources checked October 2026.
Corrections
Spotted an error? Tell us and we will fix it.