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. The site's default145 lb/ft³ corresponds to about 108.75 LB/(SY·IN), so it gives a result about 1.1% lower than the 110 shorthand. We uselb/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)
Higher-density planning input	150 lb/ft³	Editable input; confirm the project mix design
Lower-density planning input	135 lb/ft³	Editable input; confirm the project mix design

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.

When you start from dimensions or a known area, the tool calculates net quantity and then applies the visible order allowance. When you enter a supplier's known order quantity, that number is priced directly and the allowance is not added again. Calculations keep full precision internally; tables and result cards round only their displayed value.

Government binder escalation indexes (FHWA EFL) and public-project DOT bid prices are not used as your local material price. See data sources for why.

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.

Review dates and corrections

This site does not present a live price feed or an unchanging engineering standard. Source pages record their retrieval date and scope, and calculator defaults remain visible and editable. If you find a source, formula, or wording issue, send the page URL and supporting reference through the contact page. Our editorial policy explains how corrections and updates are reviewed.