Methodology

Calculator pages show a worked example produced by the same function the live tool calls. If the example and the interactive result disagree, that is a bug.

Rounding (formatQty)

Shopping-list numbers use Intl.NumberFormat with roundingMode: 'halfExpand'. Cubic yards and weights show two decimals where needed; gallon and count lines round to whole numbers; salt purchase weight shows one decimal (for example 267.0 lb). Negative zero is stripped so tiny negatives do not display as “-0.00”.

Volume materials

Gravel, mulch, topsoil, and compost convert net area × depth to cubic feet, apply waste or settling, then to cubic yards, tons, or bags. Bulk orders can round up to the next 0.5 yd³ for supplier minimums. Densities in each tool’s materials table are generated from materials.ts; the Engineering ToolBox dirt and mud page is the starting reference for several values (ETB_DIRT_MUD, verified).

Pavers and base course links

Paver counts use the module area including joint width. Straight and herringbone layouts suggest different waste percentages (WASTE_CONSENSUS, verified as defaults you can override). Links to the gravel calculator for base course use the net paved area plus about six inches on each side and a 20% compaction allowance on crushed stone (COMPACTION_ALLOWANCE, pending a single industry citation).

Grout

Grout pounds follow the perimeter form ((L+W)/(L×W)) × joint width × joint depth × area × density. Face-area methods on some bag labels can read about 1.5%–4.5% lower than this joint-volume approach; bag coverage charts still win at the store (GROUT_FACE_METHOD, verified geometry with bag-label caveat).

Wallpaper

Area yield uses the Wallcoverings Association table bands (pending direct URL, WA_WALLPAPER). Strip mode groups equal cut lengths before counting rolls, and half-drop sequencing adds half a repeat between pairs without inflating the cut length first.

Pool water and salt

Pool volume shows department gallons at 7.5 gal/ft³ and a second line at 1728/231 gal/ft³. On the default 16×32 ft pool that is 18,240 versus 18,193 exact gallons. A 24 ft diameter pool at 4 ft constant depth is 13,572 department gallons and 13,536 exact gallons in the same engine tests.

The ×7.5 factor is a department-style shortcut (POOL_75, pending official handout URL). Exact gallons use 231 in³ per US gallon (US_GALLON_231, verified definition). Salt mass uses 8.345 lb per gallon of water and ppm as parts per million by mass (SALT_MASS_FRACTION, verified). Hayward, Pentair, and Jandy presets are ideal starting points only until each manual is rechecked (SALT_PRESET_*, pending).

Source registry

• Engineering ToolBox — dirt and mud densities

  ETB_DIRT_MUD · professional · Verified against source

  Open reference

• US gallon definition (231 cubic inches)

  US_GALLON_231 · official · Verified against source

• Wallcoverings Association — How to Estimate wallpaper

  WA_WALLPAPER · official quoted · Pending check against primary source

• Department-style 7.5 US gallons per cubic foot of water

  POOL_75 · official quoted · Pending check against primary source

• Salt mass from ppm, pool volume, and 8.345 lb/gal water density

  SALT_MASS_FRACTION · consensus · Verified against source

• Hayward AquaRite ideal salt level (3,200 ppm)

  SALT_PRESET_HAYWARD · professional · Pending check against primary source

• Pentair IntelliChlor Plus / LT ideal salt level (3,600 ppm)

  SALT_PRESET_PENTAIR · professional · Pending check against primary source

• Jandy AquaPure / TruClear ideal salt level (3,000 ppm)

  SALT_PRESET_JANDY · professional · Pending check against primary source

• Base-course compaction allowance (~15–25%, paver links use 20%)

  COMPACTION_ALLOWANCE · consensus · Pending check against primary source

• Perimeter joint-volume grout estimate from tile size and joint depth

  GROUT_FACE_METHOD · consensus · Verified against source

• Layout waste defaults (paver, tile, sod) as overridable consensus values

  WASTE_CONSENSUS · consensus · Verified against source