Glossary & Sources

Authoritative references for the project-calculator factors, unit definitions, and conversion factors used throughout AllUnits.io. Calculator sources are listed first; click any converter name to go directly to that converter.

Methodology

Conversion factors on AllUnits.io are sourced from primary metrology references in this priority order:

  1. BIPM SI Brochure (9th ed.) for SI base and derived units.
  2. NIST SP 811 for exact US customary / imperial conversions (e.g., inch = 25.4 mm exactly, pound = 0.45359237 kg exactly).
  3. IEC / ISO 80000 for international quantities and digital storage prefixes (KiB vs KB).
  4. Wikipedia as a cross-check and for historical context, never as a primary source for the factor itself.

Calculations run client-side at IEEE 754 double precision (≈15–17 significant digits) and route through a base unit per category to keep all pair conversions consistent. See About AllUnits.io for the full methodology.

Concrete — Quikrete product data

Used by: Concrete Slab, Fence Posts, Sonotube / Footings, Concrete Block

Pavers — ICPI / CMHA

  • CMHA resource library the Interlocking Concrete Pavement Institute (ICPI) merged into the Concrete Masonry & Hardscapes Association; its Tech Specs live here
  • ICPI Tech Spec 2/4 compacted aggregate base: 4" pedestrian, 6–8" vehicular
  • ICPI Tech Spec 17 bedding sand: 1" nominal, never over 1.5", ASTM C33 coarse concrete sand
  • Polymeric sand manufacturers (SEK PolySweep, Alliance Gator) 40 lb bag covers 40–100 sq ft by joint width; calculator uses the 70 sq ft midpoint
Used by: Pavers & Base

Retaining walls — Allan Block

  • Allan Block installation guidance minimum 6" compacted gravel base; bury 1" per 8" of exposed height; wall rock compacted 12" behind the wall; drain pipe for reinforced walls, gravity walls over 4 ft, or poor drainage
  • Trench width (block depth + 6") approximate — Allan Block specifies base depth and backfill zone firmly, not trench width
Used by: Retaining Wall

Lumber — NIST PS 20

Used by: Board Feet, Deck Boards, Fence Posts, Stairs

Stairs & framing — IRC 2021

  • International Residential Code 2021 R311.7.5.1: max riser 7¾" with ≤ 3/8" variation per flight; R311.7.5.2: min tread 10"; R311.7.1: min stair width 36"; R602.3: stud spacing
  • Local amendments can be stricter — the permit office has the final word
Used by: Stairs

Decking practice

Used by: Deck Boards

Deck stain coverage

Used by: Deck Stain

Sod — TPI pallet standard

  • Turfgrass Producers International 450 sq ft is the US industry-standard pallet; regional range 400 (southern slabs) to 600 (northern rolls)
  • Sod Solutions cross-reference for pallet coverage and piece sizes; farm sizes vary — always confirm
Used by: Sod

Aggregate densities

  • Published quarry/supplier charts typical values: crushed stone #57 ≈ 1.40 t/yd³ (range 1.35–1.5), crusher run/DGA 1.50, pea gravel 1.40, washed sand 1.35, river rock 1.40 (range 1.3–1.5)
  • Gravelshop and Hello Gravel example published charts; every calculator using these labels them "typical — your supplier's scale ticket governs"
  • Compacted-base allowance +15% rule of thumb (range 10–20%)
  • River rock coverage 1 ton ≈ 90–100 sq ft at a 2" depth for 1–2" stone
Used by: Gravel & Stone, River Rock, Pavers & Base, Retaining Wall

Landscaping estimating figures

  • The "324 rule" 1 yd³ of mulch covers 324 sq ft at 1" — industry-standard estimating figure (324 = 27 cu ft × 12)
  • Mulch bags 2 cu ft standard (13.5 bags/yd³); 3 cu ft option (9 bags/yd³) — retail bag sizes
  • Topsoil bags 40 lb bag ≈ 0.75 cu ft → 36 bags/yd³ — standard retail fill per store listings
  • Topsoil weight roughly 2,000–2,700 lb per yd³ by moisture — always shown as a range, order by volume
Used by: Mulch, Topsoil

Turf — university seeding rates

Used by: Grass Seed

Length ↗

Weight & Mass ↗

Temperature ↗

Volume ↗

Area ↗

Time ↗

Speed ↗

Cooking ↗

Fuel Efficiency ↗

Pressure ↗

Energy ↗

Power ↗

Force ↗

Torque ↗

Angle ↗

Frequency ↗

Digital Storage ↗

Number Base ↗

Currency ↗

Pace ↗

  • World Athletics official road race distance standards; min/km and min/mile pace references
  • Wikipedia: Pace (speed) pace as inverse of speed; relationship to time-per-distance metrics
  • NIST SP 811 mile = 1,609.344 m exactly; basis for min/mile ↔ min/km conversion

Density ↗

Flow Rate ↗

Data Transfer Rate ↗

Illuminance ↗

Typography Units ↗

Electric Units ↗