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Tile Area, Quantity, Waste, Box, and Cost Formulas

Use tile formulas for surface area, excluded openings, tile face area, waste allowance, whole boxes, purchased coverage, spare tiles, and cost.

How do the Tile Calculator formulas work?

This formula page defines the variables used by the Tile Calculator, shows how those values are combined, and explains the order of operations behind the result. Use the worked steps to verify an estimate, compare scenarios, and understand which assumptions or rounding rules can affect the displayed answer.

Formula Overview

The engine normalizes project and tile dimensions, subtracts excluded area, calculates a base whole-tile count, applies waste, rounds to whole boxes, and uses the entered rates for material and labor estimates.

Variable Definitions

  • L, W, and q: surface length, width, and identical-area quantity
  • E: excluded untiled area
  • l and w: one tile's face length and width
  • r: entered waste percentage
  • p: entered tiles per box
  • P: entered price per box
  • R: entered labor rate per net square foot

Gross and Net Surface Area

Agross=L×W×qA_{gross}=L\times W\times q
Anet=Agross−EA_{net}=A_{gross}-E

Project dimensions and the excluded area are converted to square feet before subtraction. Net area must remain greater than zero.

Tile Face Area

atile=l×wa_{tile}=l\times w
atile,ft2=atile,in2144a_{tile,ft^2}=\frac{a_{tile,in^2}}{144}

Both tile dimensions use the same selected unit. The formula uses nominal face area and does not create a row-by-row grout-joint layout.

Tile and Box Counts

Tbase=⌈Anetatile⌉T_{base}=\left\lceil\frac{A_{net}}{a_{tile}}\right\rceil
Torder=⌈Tbase(1+r100)⌉T_{order}=\left\lceil T_{base}\left(1+\frac{r}{100}\right)\right\rceil
Boxes=⌈Torderp⌉Boxes=\left\lceil\frac{T_{order}}{p}\right\rceil

Rounding occurs after each discrete purchase stage: first base pieces, then waste-adjusted pieces, then whole boxes.

Purchased Coverage and Spare Tiles

Tpurchased=Boxes×pT_{purchased}=Boxes\times p
Coveragepurchased=Tpurchased×atileCoverage_{purchased}=T_{purchased}\times a_{tile}
Spare tiles=Tpurchased−TbaseSpare\ tiles=T_{purchased}-T_{base}

Material and Labor Cost

Material cost=Boxes×PMaterial\ cost=Boxes\times P
Labor cost=Anet×RLabor\ cost=A_{net}\times R
Combined estimate=Material cost+Labor costCombined\ estimate=Material\ cost+Labor\ cost

The cost model uses only the entered tile-box price and net-area labor rate.

Worked Floor-Tile Calculation

For a 10 ft × 12 ft floor with no excluded area, net area is 120 ft². A 12 × 24 inch tile covers 2 ft²:

Tbase=⌈120/2⌉=60T_{base}=\left\lceil120/2\right\rceil=60
Torder=⌈60×1.10⌉=66T_{order}=\left\lceil60\times1.10\right\rceil=66
Boxes=⌈66/8⌉=9Boxes=\left\lceil66/8\right\rceil=9

Nine boxes contain 72 tiles, so purchased coverage is 144 ft² and spare tiles above the base count equal 12.

Assumptions and Boundaries

  • Entered surfaces are uniform rectangles.
  • Excluded area is smaller than gross area.
  • Tile dimensions represent nominal face dimensions.
  • Waste applies after base pieces round upward.
  • Boxes use the exact entered package count.
  • Layout, joints, cuts, trim, setting materials, and substrate work are excluded.

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