Methodology
How every number on this site is computed — the model, the units, the defaults, and what we deliberately leave out.
The calculation model
Every calculator on this site starts from the same four-step model. No intermediate value is rounded; rounding happens only when a number is shown to you.
| Area | length × width |
| Volume | area × compacted thickness |
| Net weight | volume × compacted density |
| Order weight | net weight × (1 + waste allowance) |
| Material cost | order weight × price per ton |
| Truckloads | ceil(order weight ÷ truck capacity) |
Units
All arithmetic runs in metric internally — meters, cubic meters, kilograms. US units (feet, inches, pounds per cubic foot, short tons) exist only at the input and output boundary. This means the US and Metric views of the same project differ only by display rounding, never by a different formula. That guarantee is covered by automated tests.
The industry shorthand 110 LB/(SY·IN) — 110 pounds per square yard per inch — equals 146.67 lb/ft³. Both give the same answer; we use lb/ft³ because it composes cleanly with area and thickness.
Density defaults
Density is the input most likely to be wrong, so we make it explicit and editable. The presets are common industry planning values for compacted hot mix, not engineering specifications:
| Mix | Density | Basis |
|---|---|---|
| Standard hot mix (dense-graded) | 145 lb/ft³ | Common planning value; ~109 LB/(SY·IN) |
| Heavy / fine-graded | 150 lb/ft³ | Upper end of typical compacted range |
| Open-graded / porous | 135 lb/ft³ | Compacts lighter due to air voids |
Always confirm the actual compacted density with your plant's mix design. The calculator warns you if a custom density falls outside the typical 100–170 lb/ft³ range, which usually indicates a unit mix-up.
Waste allowance
The default 5% covers edge trimming, rake-out, and mix that doesn't make it into the mat. Irregular shapes or small patches may justify more. The allowance is applied to the net quantity and shown as a separate line, never baked into the density.
Cost methodology
The cost calculator keeps three price bases separate — material only, material + delivery, and installed — and never renames one as another. Material cost is computed from the order tonnage and your per-ton price. On-site costs (demolition, base prep, labor) are entered by you. The installed figure is shown as a planning range produced by an explicit contingency you control, applied to the on-site work — not as false precision.
What the numbers do not include
- Base course and subgrade preparation (unless you add a base layer in the driveway calculator).
- Drainage, compaction lift limits, and pavement design.
- Delivery, labor, and tax — unless you enter them in the cost calculator.
These are planning estimates. Final pavement design depends on soil, drainage, climate, traffic, local code, and contractor or engineer recommendations.
Testing
The calculation core is pure TypeScript with a unit-test suite covering unit conversions, the quantity model, pricing provenance guards, the cost breakdown, and US/Metric consistency. The build also runs an automated verification step that rejects output missing required SEO and data guarantees.