Tile Calculator

Tiles, boxes, grout and thinset for a floor, shower or backsplash, with waste set by layout (straight, diagonal or herringbone).

Porcelain floor tile being laid in a bathroom A bathroom floor of cement backer board with blue chalk layout lines. A notched trowel combs thinset one row at a time, then 12 by 24 inch porcelain tiles are set from the centre line outwards with spacers in the joints. In front: a bucket of thinset with a mixing paddle, boxes of tile, a bag of spacers and a manual rail tile cutter scoring and snapping a tile. THINSET MODIFIED PORCELAIN 12×24 8 PCS · 15.5 SQ FT

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Tile reference

⅜″½″¾″ ⅜″ PORCELAIN TILEGROUT JOINT, ⅛–3⁄16″THINSET, 80–95% COVERAGE½″ CEMENT BOARD, SCREWS 8″ O.C.¾″ PLYWOOD SUBFLOORJOIST, DEFLECTION L/360 MIN.¼″ GAP AT WALL, SEALANT
Typical section. Over concrete, or with an uncoupling membrane, the membrane replaces the cement board; follow the manufacturer's method.

Trowel notch

Mosaic, up to 2″
3⁄16″ V-notch
Tile up to 8″
¼ × ¼″ square
Tile 8″ to 15″
¼ × ⅜″ square
Tile 15″ and larger
½ × ½″ square
Mortar coverage
80% dry, 95% wet

Grout

Joint under ⅛″
Unsanded
Joint ⅛″ and wider
Sanded
Rectified tile
1⁄16–⅛″ joint
Calibrated tile
⅛–3⁄16″ joint
Showers, stain-prone
Epoxy or urethane

Layout and waste

Straight lay
10%
Diagonal
15%
Herringbone
20%
Offset, tile over 18″
⅓ maximum
Edge cuts
½ tile or more

Substrate and timing

Flatness, large format
⅛″ in 10 ft
Joists, ceramic
L/360
Joists, natural stone
L/720
Thinset before grouting
24 h
Grout before sealing
48–72 h

Safety Cutting tile and cement board makes silica dust. Score and snap or cut wet, wear an N95 mask and eye protection, and wear gloves: thinset and grout are caustic.

Full notes
  • Waste: about 10% for straight layouts, 15% for diagonal, 20% for herringbone or small rooms with many cuts.
  • Buy one extra box for future repairs. Dye lots vary, so you may never match the tile again.
  • Large-format tiles need very flat subfloors and a larger trowel notch, which uses more thinset.
  • Grout depends on tile size, joint width and tile thickness: wide joints and small tiles use much more.
  • Comb thinset in straight lines in one direction, only as much as you can set in 15 to 20 minutes, and lift a tile now and then to check coverage.
  • Back-butter tiles 15 in and larger with a thin flat coat as well as combing the floor.
  • Leave a ¼ in gap at every wall, tub and change of plane and fill it with flexible sealant, not grout. Large floors also need field movement joints, about every 20 to 25 ft indoors (closer in sun or wet areas).
  • Showers and other wet areas need a waterproofing membrane over the backer board, or a bonded sheet membrane system. Cement board on its own is not waterproof.
  • Cure times vary with the product, temperature and humidity. Follow the thinset and grout labels; rapid-set products can be grouted in a few hours.

Planning a bigger project?

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Common room sizes

Drag to change the size
12 × 14 ft168 ft²
12 × 14 ft room185 tiles
5 × 8 ft15 × 20 ft

Drag the corner of the shape or the slider. Grid squares are 2 ft. Tap a result to load it into the calculator.