Transparent inputs, separate outputs
We use metres, square metres, cubic metres and kilograms internally. The site calculates geometry from your entered dimensions; it does not select an installation depth or material specification. All default measurements are editable arithmetic examples. Waste starts at 0%, the loose-volume multiplier at 1 and density is blank.
Area = length × width, or π × radius²
Geometry = area × depth × identical-area count
Loose requirement = geometry × loose-volume multiplier
Order volume = loose requirement × (1 + waste% ÷ 100)
Estimated mass = order volume × supplier loose bulk density
Exact unit definitions
| Unit | Definition used |
|---|---|
| Foot | 0.3048 m |
| Inch | 0.0254 m |
| Yard | 0.9144 m |
| Cubic foot | 0.028316846592 m³ |
| Cubic yard | 0.764554857984 m³ = 27 ft³ |
| Litre | 0.001 m³ |
| Pound | 0.45359237 kg |
| US short ton | 2,000 lb = 907.18474 kg |
| Metric tonne | 1,000 kg |
Sources: NIST international-foot definitions and NIST Handbook 130 unit tables. Inch, yard and volume factors follow from these definitions. Source/assumption register reviewed 7 October 2026.
Bags and costs
Volume bags use order volume divided by bag volume. Mass bags first need your loose bulk density to convert bag mass to a compatible volume. Required whole bags round up before cost is calculated. A tiny floating-point correction within four machine epsilons at an integer boundary avoids spurious extra bags; it is not an ordering tolerance. Visible decimal rounding is never used to compute bags.
Per-bag cost uses purchased whole bags. Bulk volume or mass prices use the unrounded order requirement, before a supplier’s minimum order or delivery increment. Tax, delivery, equipment and labour are excluded. Currency is a label for your input, not a conversion service.
Input and numerical limits
Required sizes are positive finite decimal numbers, no more than one billion in the selected unit. Identical areas must be a whole number from 1 to 10,000; reverse-coverage stock is 1 to 1,000,000 whole bags. Waste accepts 0–100%, multiplier 1–10, density up to 10,000,000 in the selected unit and price 0–1 billion. Calculated quantities above 1 trillion SI units, underflow to zero or unsafe bag counts are rejected. Costs above 1 quadrillion currency units are rejected. These are software bounds, not practical project recommendations.
Results normally display up to three decimal places, with scientific notation for very small/large values. Mass remains an estimate even when the geometry is precise. Independent engine checks target relative error within 1e-9 for nonzero reference quantities; boundary and bag-count tests check integer results separately.
What this cannot tell you
It does not assess structural safety, drainage, ground conditions, soil quality, delivery access or product suitability. No supplier prices or generic densities are maintained. Confirm the order and all material-dependent assumptions with a suitable supplier or project professional.