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Tile Calculator

Tile is only the first thing you buy. Give us the area and the tile and you'll get the boxes, the thinset, the grout, and the backer board, with the waste driven by the pattern you're laying.

  • Boxes and pieces
  • Thinset and grout
  • Shower waterproofing

Project measurements

Where is the tile going? This sets the substrate and the fixing

Any floor: bathroom, kitchen, hall. Length times width, measured wall to wall.

Measurements Tape measure or decimals

ft
ft
ft
ft
in
in
mm
in

The tile Sets the price and the fixings

Layout Sets the waste and the labor

Thinset trowel

How this number is built

A tiled surface is five materials: the tile, the thinset, the grout, the backer board, and the waterproofing where it is wet. The tile box is the only one with no standard coverage figure, so this page asks for the label's square footage rather than assuming one.

There is no standard square footage in a box

Measured 12 × 24 porcelain across four products runs 13.56, 15.12, 15.63, and 17.02 sq ft per box: the same nominal tile size, a 25% spread. 12 × 12 varies the same way. The label on your box is the authority, which is why this page asks for it rather than assuming one.

Waste is about the pattern, not the material

Straight lay takes about 10%, brick bond 12%, diagonal 15%, herringbone 18%, and more for intricate patterns or a room full of obstacles. One caveat: the familiar 10/15/20% split is estimating convention, widely attributed to the TCNA, but the TCNA Handbook does not publish a single universal waste percentage; it classifies installation methods and the cut loss follows from those. These numbers are practice, not a standard.

Buy extra for dye lot, not just waste

Tile is fired in runs, and a different production run can be a visibly different shade. Running out mid-job does not just mean buying more tile: it means a visible patch or a re-do. Buy the whole job at once from one lot and keep 5–10 spares (for a repair in five years, not for waste).

Thinset coverage depends on the trowel size

The notch size sets the coverage: a 50 lb bag covers about 80–100 sq ft at 1/4 × 1/4, 60–80 at 1/4 × 3/8, and only 40–50 at 1/2 × 1/2. Large-format tile needs the big notch because the ridges must collapse to full contact underneath. A hollow spot under a large tile can crack it. And tile is never bonded straight to plywood: backer board or an uncoupling membrane goes between.

Grout coverage can be calculated

Grout coverage is not a constant: it depends on the tile size, its thickness and the joint width, and manufacturers give a density factor rather than a table. The model here is lb/ft² = 0.2048 × K × (L+W) ÷ (L×W) × thickness × joint with K = 1.6 for a typical polymer-modified cement grout, all in millimeters. It reproduces Mapei's own published chart to within a percent, which is why the page can compute it rather than guess. Two product rules: sanded grout for joints from 1/8 to 1/2 inch, unsanded for 1/16 to 1/8, and epoxy is a different product with its own coverage and price.

Wet areas need waterproofing on one side of the backer board, not both

Per TCNA's shower details, a shower assembly carries either an ANSI A118.10 bonded waterproof membrane over the backer board or a vapor retarder membrane behind it. Never both. With a membrane on each side, moisture that gets in between has no way out. The membrane has to be continuous through every change of plane (corners and the wall-to-floor junction are where leaks happen), it must run to the full tile height, the pan has to fall at 1/4 inch per foot to the drain, and the pan gets a flood test before any tile goes down. Thinset over a membrane has to be ANSI A118.4 or better unless the membrane maker says otherwise.

Grout coverage, per 25 lb bag

Tile Thickness 1/8 in joint 3/16 in joint 1/4 in joint
12 × 12 10 mm 366 sq ft 244 183
12 × 24 10 mm 488 sq ft 325 244
24 × 24 10 mm 732 sq ft 488 366
6 × 6 9.5 mm 193 sq ft 128 96
3 × 6 subway 7 mm 174 sq ft 116 87
2 × 2 mosaic 6 mm 102 sq ft 68 51

Every figure is K × (L+W) ÷ (L×W) × thickness × joint with K = 1.6, computed here, so any tile size, thickness, and joint is exact. Grout charts assume the joints are filled to full depth, so a shallow strike or a wide sponge pulls the real coverage down and the bag count up (allow for cleanup). These are cement grouts, so epoxy is a different product with its own coverage and a much higher price.

Measuring the room first? The square footage calculator works out the area of any shape and carries it straight over here.

Where these numbers come from

  • Mapei's published coverage chart and density-factor guidance for Ultracolor Plus and Keracolor, cross-checked against Custom Building Products' grout coverage card. The K = 1.6 factor and the 0.2048 imperial conversion are the manufacturer's model, and it reproduces Mapei's own published chart to within a percent.
  • Manufacturer technical data sheets per 50 lb bag: Mapei (80–100 / 60–80 / 40–50 by notch), Custom Building Products (90–100 / 63–70 / 45–50) and LATICRETE (80–95 / 40–55, with no figure published for the middle notch). The page shows a range because the three manufacturers do not agree exactly.
  • Box sizes were checked: 12 × 24 in porcelain across Caesar Ceramics and Daltile listings runs 13.56, 15.12, 15.63, and 17.02 sq ft per box.
  • TCNA Handbook shower details (B415, W244) and ANSI A118.10, read via UPC report language and a manufacturer installation kit rather than the Handbook itself, which is a purchased document. The one-side-only rule, continuity through plane changes, the 1/4 inch per foot slope, and the flood test all come from that set.
  • Estimating convention rather than a published standard. The TCNA Handbook classifies installation methods and pattern orientations; it does not publish a universal waste percentage, and this page says so rather than attributing the numbers to it.
  • 2026 tile cost guides and retail listings. Secondary sources only: no tile-specific price index was identified, because BLS's nonmetallic-mineral grouping is too broad and no ceramic-tile subseries could be confirmed. Read these as retail listings, not trade figures.