Every number this site asserts comes from one of three places: a manufacturer’s published data sheet, a typical industry range from a supplier or reference table, or a definitional conversion. This page lists them all, so you can check the inputs before you trust the outputs. Estimates that vary by supplier are always editable in the calculators themselves.

Concrete bag yields (manufacturer-published)

• QUIKRETE concrete mix — 80 lb bag yields 0.60 ft³; 60 lb, 0.45 ft³; 40 lb, 0.30 ft³ — QUIKRETE data sheet (PDF)
• SAKRETE / Basalite concrete mix (metric) — 25 kg bag yields approximately 0.0116 m³ ≈ 0.414 ft³ — product page · data sheet (PDF)
• SAKRETE high-strength mix TDS — supplier-reported yield figures for comparison — technical data sheet (PDF)

Yield disclaimer: published yields are nominal; real-world yield shifts with water content, compaction and mixing losses. Counts are computed with ceil(volume ÷ yield), so a small error shows as a margin, not a shortage.

Gravel & topsoil densities (typical industry ranges)

• QUIKRETE all-purpose gravel — 50 lb bag ≈ 0.5 ft³ — product page
• Material weight & coverage tables — loose gravel ~2,600–2,800 lb/yd³, topsoil ~2,000–2,400 lb/yd³, sand ~2,700 lb/yd³, lava rock ~1,500 lb/yd³ — Mulch Pros weight & coverage, aggregate density reference, gravel weight chart

Density disclaimer: these are typical loose/compacted ranges, not specs. A supplier’s scale ticket is authoritative — that’s why every density on this site is a live input you can replace.

Concrete weight

• Normal-weight concrete ~150 lb/ft³ (≈2,400 kg/m³, ≈4,050 lb/yd³) — Iowa DOT IM 340 lists the normal range as ~140–150 lb/ft³ — IM 340; corroborating reference: CivilToday density of concrete

Mulch depth guidance

• University of Illinois Extension, “Proper Mulching Techniques” — 2–4 in typical, never against trunks — extension fact sheet (PDF)
• Virginia Tech / Virginia Cooperative Extension SPES-661 — mulch depth by use, volcano-mulching warnings — SPES-661 (PDF)

Paver installation guidance

• Paver installation guide (pedestrian spec) — 4–6 in compacted aggregate base + ~1 in bedding sand — install guide (PDF)
• CMHA/ICPI guide specification PAV-GSP-011-21-US — industry installation spec for concrete pavers — guide spec (PDF)
• Sand and compacted-base densities — from the aggregate density references above.

Safety — call before you dig

• 811, “Call Before You Dig” (US) — free utility locating a few business days before excavation for footings, post holes, drains or paver base — call811.com

Unit conversions (definitional)

• 1 ft = 0.3048 m · 1 in = 2.54 cm · 1 ft² = 0.09290304 m² · 1 ft³ = 0.0283168 m³ · 1 yd³ = 27 ft³ = 0.764555 m³ · 1 lb = 0.45359237 kg · 1 US ton = 2,000 lb · 1 tonne = 1,000 kg

What we assume on every page

• Rectangular areas are L × W × D; steps are stacked boxes; columns are cylinders — all straight geometry, shown on each page.
• Waste margins are a judgment call you control (0–30%), not a hidden constant.
• Prices entered are multiplied by the quantity — no tax, delivery, or short-load fees are modeled unless noted.
• These are estimating tools, not engineering or construction advice. Verify against your supplier’s numbers and local code before ordering or digging — see the disclaimer.