Area and volume
We convert lengths to meters, areas to square meters, volume to cubic meters and mass to kilograms before calculation. Precision is retained until display and purchasing rounds.
- Rectangle: length × width.
- Circle: π × (diameter ÷ 2)².
- Triangle: base × perpendicular height ÷ 2.
- Trapezoid: (parallel base 1 + base 2) × height ÷ 2.
- Polygon: shoelace area; invalid crossing or self-touching boundaries are rejected. Polygon clipping subtracts the union of holes, so overlapping holes are not counted twice.
- Volume: net area × layer depth. In feet/feet/inches, cubic yards = length × width × depth ÷ 324.
An independently reproducible example
20 ft × 10 ft × 4 in = 66.6666667 ft³ = 2.4691358 yd³. Adding 5% gives 2.5925926 yd³ before any supplier rounding. Every layer is calculated separately, including its own density and pricing.
Density: a planning assumption, not a product certification
All named presets start at 1,600 kg/m³. This intentionally rounded assumption is informed by a Red Flint supplier document, page 2, which uses 100 lb/ft³ for its sand and gravel. That converts to approximately 1,601.85 kg/m³. The source concerns specified filtration materials; it does not certify every landscaping aggregate.
Pea gravel, crushed stone and general gravel labels are project categories here, not distinct laboratory measurements. Replace density with your supplier’s figure. Moisture, particle grading, voids and compaction affect delivered material. Vulcan’s estimator also separates geology and product categories and cautions that project conditions affect final quantities.
Exact conversion constants
| Unit | SI equivalent |
|---|---|
| 1 inch | 0.0254 m |
| 1 foot | 0.3048 m |
| 1 cubic yard | 0.764554857984 m³ |
| 1 pound | 0.45359237 kg |
| 1 US short ton | 907.18474 kg (2,000 lb) |
| 1 metric tonne | 1,000 kg |
Reference: NIST Handbook 44, Appendix C. A UK long ton is not a supported purchase unit.
Allowances and purchasing
Order volume = measured volume × (1 + extra percent/100) × (1 + loose-volume adjustment/100). Both factors are editable and separate. Use only justified factors. Purchase quantity is max(required quantity, supplier minimum), then rounded up to the chosen increment. Bag counts round up after dividing required volume by yield, or required mass by bag mass.
Price = purchased quantity × entered unit price, plus entered delivery, multiplied by (1 + entered tax/100). All prices share the user’s entered currency. Missing prices remain missing, rather than becoming zero. Delivery is charged per layer quote; consolidated deliveries must be negotiated separately.
Measurement limitations
Sections are independent sums with an explicit overlap warning; there is no inferred site positioning or automatic union between named sections. Layers share the same footprint at different depths. Numeric cutout area is additional to polygon holes. A calibrated plan must be top-down and uniformly scaled. Images remain in memory. Maps estimate horizontal area from coordinates using Turf area; slope, surface condition and depth are not measured.
Product guidance is contextual
Sakrete’s product sheet supplies a specific labelled bag yield and application examples. We do not treat those as a universal driveway design or silently copy a yield to other products.
No licensed engineer review is claimed. Sources inform assumptions; they do not endorse this site. Check a calculation against our examples.