Sources & formulas

Every calculator on FloorsCalcs rests on established arithmetic plus stable flooring conventions. Unlike topics with a time dependency, "verification" here is mathematical: each formula is tested against known values and is therefore correct for good. Here are the technical foundations by area.

Identities & geometry

  • Area: floor area (sq ft) = length_ft × width_ft; an L-shaped room is the sum of its rectangles.
  • Unit identities: 9 sq ft = 1 square yard (carpet); a 4×8 subfloor sheet = 32 sq ft; whole units (boxes, tiles, rolls, bags, sheets, pieces, kits) always round up with ceil().

Quantity conventions (labeled typicals)

  • Waste factor: straight lay ~5–10%, diagonal ~15%, herringbone/chevron ~15–20% — labeled typicals.
  • Box coverage: a box typically covers ~20 sq ft; plank and tile sizes vary by product.
  • Grout & thinset: grout lb/sq ft by tile size + joint; thinset ~40–50 sq ft per 50-lb bag (1/4" notch), ~25–30 sq ft (1/2" notch) — labeled, confirm on the bag.
  • Underlayment / leveler / vapor: underlayment ~100 sq ft/roll, vapor ~200 sq ft/roll, self-leveler ~10 sq ft·in per 50-lb bag — labeled typicals.
  • Expansion gap & acclimation: laminate/LVP ~1/4"–3/8", engineered ~1/2", solid hardwood ~3/4"; acclimation typically 48–72 h — labeled, confirm on the manufacturer’s instructions.

Cost tools

  • Every cost tool uses the prices you enter ($/sq ft for material, $/hr or flat labor, $/bag, $/roll, $/ft) — no material or labor price is stored, so the site needs no maintenance. Cost bands are a labeled sanity guide.
  • Install cost: total = (area × $/sq ft + labor + Σ add-ons − discount) ×(1 + contingency).
  • Refinishing / epoxy: total = area × $/sq ft + prep + coats, ×(1 + contingency).

Material and labor prices, product coverage, permit rules and local code vary by place and change over time — always confirm coverage against your product’s box/spec sheet, buy 5–10% extra for cuts, waste and future repairs, and get itemized written quotes from a licensed, insured flooring installer before you commit.