Methodology
How every number on this site is worked out, so you can check it yourself.
Calculation steps
- Area: rectangle = length × width; circle = π × (diameter ÷ 2)²; or the area you enter.
- Volume (gravel, soil, sand, stone) = area × depth. Sod uses area only.
- With waste = quantity × (1 + waste % ÷ 100). A waste of 0% is allowed.
- Weight = volume with waste × density.
- The amount is converted into the unit your supplier sells by: cubic yards, m³, US short tons, metric tonnes, bags, rolls or pallets.
- The order rounds up to the order step set in Supplier order rules, then any minimum order applies. It never rounds down. The pre-filled step is an example; check your supplier's ordering rules.
- Sod as pallets + extra rolls: whole pallets = round down (area with waste ÷ pallet coverage); extra rolls = round up (leftover area ÷ roll coverage). If those extra rolls would together cover at least one pallet's coverage, one more pallet is ordered instead of the rolls. This split follows the coverage sizes entered and is not optimized for price.
- Cost = rounded order × your price per that unit, plus delivery, plus optional tax on both.
The site works internally in metres, square metres and cubic metres at full precision. Rounding happens only for display and for the final order.
Conversion constants
- 1 ft = 0.3048 m; 1 in = 0.0254 m
- 1 cubic yard = 27 cubic feet = 0.764554857984 m³
- 1 cubic foot = 0.028316846592 m³
- 1 lb = 0.45359237 kg
- 1 US short ton = 2,000 lb = 907.18474 kg
- 1 metric tonne = 1,000 kg
- 1 acre = 4,046.8564224 m²
Indicative densities
These are rough, loose-material figures used only when you haven't entered your own. Real density depends on the stone or soil, grading and moisture. Your supplier's figure is always better.
| Material | t/m³ | lb/cu yd |
|---|---|---|
| Gravel: Crushed gravel | 1.5 | 2528 |
| Gravel: Pea gravel | 1.5 | 2528 |
| Gravel: River gravel | 1.6 | 2697 |
| Gravel: General aggregate | 1.5 | 2528 |
| Topsoil: Screened topsoil | 1.2 | 2023 |
| Topsoil: Garden soil mix | 1.1 | 1854 |
| Sand: Bedding sand | 1.6 | 2697 |
| Sand: Leveling sand | 1.6 | 2697 |
| Sand: General landscaping sand | 1.55 | 2613 |
| Decorative stone: Pea gravel | 1.5 | 2528 |
| Decorative stone: River rock | 1.6 | 2697 |
| Decorative stone: Crushed decorative stone | 1.5 | 2528 |
Combining project areas
- Each area gets its own waste allowance, so a 5% area and a 15% area are each handled correctly.
- Matching areas are added together before rounding, so you don't round up several times.
- Areas are combined only when the material, density, purchase unit, packaging, order rules and price all match. Otherwise they stay on separate lines, with the reason shown.
- When combined areas list different delivery fees, the largest one is used once, because they're treated as one order.
What the estimates do not cover
- Compaction isn't added automatically. If you expect it, include it in the waste allowance.
- Prices are never filled in for you. The site has no live retailer prices.
- This isn't structural or engineering advice. For driveways that carry vehicles, retaining walls or other load-bearing work, talk to a qualified local professional.