Every calculator on this site is built from published engineering constants and standard trade formulas — not scraped numbers. This page documents where the math comes from so you can verify any result.
Volume & tonnage formulas
All area-based material calculators use the same physical chain: Length × Width × Depth = volume, then volume × material density = weight. Depths entered in inches are divided by 12; cubic feet divide by 27 for cubic yards; pounds divide by 2,000 for US short tons. Waste allowances (typically 5–10%) and compaction allowances follow common trade practice and are shown as editable fields, never hidden multipliers.
Density values used
| Material | Density (lb/ft³) | Basis |
|---|---|---|
| Hot mix asphalt (compacted) | 142–148 (we use 145) | Asphalt Institute MS-2; mix designs per ASTM D3515 / AASHTO M323 |
| Asphalt millings (loose RAP) | 135–145 (we use 140) | FHWA RAP usage guidance |
| Crushed stone / dense-graded base | 118–125 (we use 120) | AASHTO M147 gradations, quarry spec sheets |
| Loose gravel | 100–110 (we use 105) | Typical supplier spec, rounded stone |
| Sand (dry) | 95–105 (we use 100) | ASTM C33 fine aggregate, dry bulk density |
| Concrete (normal weight) | 145–150 | ACI 318 commentary; bag yields from manufacturer data (80 lb → 0.60 cu ft) |
| Topsoil (dry) | 75–85 | USDA soil bulk density ranges |
Standards referenced across the calculators
ASTM D3515 / AASHTO M323 — hot-mix asphalt mix design (binder content 4–7%). ASTM D698 / D1557 — Standard and Modified Proctor compaction, the basis of the 95% compaction spec cited in the excavation tools. ACI 318 — structural concrete, rebar cover and reinforcement context. IRC (International Residential Code) — stair rise/run limits (7-3/4 in max riser, 10 in min tread), joist span tables, footing frost-depth requirement. NEC (NFPA 70) — conductor ampacity (Table 310.16 basis), conduit fill (Chapter 9, 40% rule), and Article 220 load calculation methods. ACCA Manual J — the professional HVAC load standard our BTU and HVAC tools approximate and always defer to. IECC — climate-zone R-value targets used in the insulation tools.
What the calculators do not do
They do not replace engineering. Structural sizing (footings, retaining walls over 4 ft, trusses), electrical installations, and HVAC equipment selection require licensed professionals and local code review. Our tools produce planning quantities and budget ranges; final numbers belong to your supplier's tickets and your inspector's sign-off.
Corrections
Found a constant that disagrees with your regional spec? Use the contact form on any page — corrections ship in the next monthly verification pass, noted in each page's “Last verified” line.