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QuantoObra

Tile Calculator

Work out how many tiles and boxes you need — plus grout and thinset — for any floor or wall, in straight, offset, diagonal or herringbone layouts.

Any surfaceFloor tileWall & backsplash

Results update as you type.

Area

Measure by
ft
ft

Tile

in
in
in

e.g. 1/16, 1/8, 3/16

in

Sets grout depth

%

Set by pattern; adjust if needed

On the box label

Setting materials & prices

$/ft²
lb
$
lb
$

Tiles needed

130tiles

Boxes
13
130 tiles
Area incl. waste
132 ft²
120 ft² net
Grout
8.6 lb
1 bag
Adhesive
95 lb
2 bags

Shopping list

  • 13Boxes of 12 × 12 in tile (10/box)

    130 tiles · 130 ft²

  • 125 lb bag of unsanded grout

    8.6 lb needed

  • 250 lb bag of tile adhesive (thinset)

    94.6 lb needed · 1/4 × 3/8 in square notch trowel

  • 1Tile spacers, sponge & grout float

    Recommended

Add prices below to see a cost estimate.

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How we calculate

tile footprint = (tile width + joint) × (tile length + joint)
tiles = ⌈area × (1 + waste %) ÷ tile footprint⌉ · boxes = ⌈tiles ÷ tiles per box⌉
grout volume = area × (W + L) ÷ (W × L) × joint × tile thickness
grout weight = volume × 1,600 kg/m³ × 1.10
thinset = area × trowel rate × (1 + waste %)

Waste by pattern: straight 10%, offset 12%, diagonal 15%, herringbone 20%. Changing the pattern resets waste to these defaults; you can still edit it.

Thinset rates (from manufacturer coverage charts): 1/4 × 1/4 in (6 mm) ≈ 2.6 kg/m², 1/4 × 3/8 in (10 mm) ≈ 3.5 kg/m², 1/2 × 1/2 in (12 mm) ≈ 5.4 kg/m².

How to calculate tiles for a room

  1. Measure the length and width of the floor (or width and height of each wall). For L-shaped rooms, split into rectangles and add the areas.
  2. Pick your tile size and grout joint — the joint is usually 1/16–1/8 in (2–3 mm) for rectified tile and 3/16–1/4 in (5–6 mm) for rustic tile.
  3. Choose the layout. Diagonal and herringbone patterns create many more cuts at the edges.
  4. Round up to whole boxes. Tile is sold by the box and dye lots vary, so buy everything at once.

Frequently asked questions

How many tiles do I need?

Divide the area by the area of one tile including one grout joint, then add waste. For 100 ft² of 12 × 12 in tile with 1/8 in joints and 10% waste: 110 ÷ 1.021 = 108 tiles.

How much extra tile should I buy?

Add 10% for straight layouts, 12% for offset/brick, 15% for diagonal and 20% for herringbone. Small rooms with many cuts need the higher end. Keep a spare box for future repairs.

How much grout do I need?

Grout depends on joint width, tile thickness and tile size: kg/m² = (L + W) ÷ (L × W) × joint × depth × 1.6 (all in mm). Small tiles and wide joints use much more grout. The calculator does this for you.

How much thinset do I need?

A 50 lb bag covers about 90–100 ft² with a 1/4 × 1/4 in notch, 60–70 ft² with 1/4 × 3/8 in, and 40–45 ft² with 1/2 × 1/2 in. Larger tiles need bigger notches.

Do I subtract the grout lines from the tile count?

Yes — each tile effectively covers its own size plus one joint. The effect is small for large tiles but adds up with mosaics and wide joints.

Sanded or unsanded grout?

Use sanded grout for joints wider than 1/8 in (3 mm) and unsanded for narrower joints or polished stone that could scratch.

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