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Tile Calculator

How many tiles you really need — with waste factored in.

Running out of tiles mid-job is a nightmare — a colour mismatch from a different production batch can ruin the whole look. Buying too many wastes money. This calculator accounts for waste, tile size, and box count so you buy exactly what you need.

Tiles to buy (10% waste)
37
Area
12.00 m²
Exact tiles
33.3
Boxes needed
7

Waste factor: 10% for standard layouts, 15% for diagonal patterns, 20% for complex mosaics. Always buy extra for future repairs — colors change between production lots.

Waste Factor: How Much Extra to Buy

The waste factor accounts for cuts, breakage, and edge pieces. Never tile with zero waste buffer — even a single broken tile late in a project can force you to buy a whole new box.

  • Straight lay (tiles parallel to walls): 10% waste
  • Diagonal (45° pattern): 15-20% waste — much more cutting
  • Herringbone or complex mosaics: 20%+ waste
  • Small rooms with lots of cuts near obstacles: add another 5%
  • Always buy at least one full box extra beyond your calculated amount for future repairs

Tile Size and Room Perception

Tile size significantly affects how a room looks and feels. Smaller tiles create more grout lines and a busier appearance; larger tiles flow better and can visually expand a space.

  • Small tiles (20×20 cm or smaller): traditional, highly textured look, more grout lines to clean
  • Standard tiles (30×30 to 45×45 cm): most common, balance of aesthetics and ease of lay
  • Large format (60×60 cm or 24×24 in): modern, minimal grout lines, harder to lay on uneven floors
  • Plank tiles: wood-look, laid in brick pattern, need extra waste budget for the pattern

Grout Line Width and Pattern

Grout lines are both structural and aesthetic. Too thin and they can't flex with thermal expansion; too wide and they dominate the appearance. Rectified tiles (precision-cut) can use 1-2mm joints; unrectified need 3-5mm.

  • Natural stone and hand-made tiles: 3-8mm joints to accommodate variation
  • Rectified porcelain: 1-3mm joints for a seamless look
  • Mosaic tiles: 2-4mm joints between tesserae, wider at sheet edges
  • Epoxy grout vs cement grout: epoxy is more stain-resistant but harder to apply; cement is standard

Substrate and Adhesive

Tiles are only as good as what's underneath. Flexible substrates (wood floors, plywood) need a membrane or decoupling layer; concrete and tile backer board are ideal.

  • Cement board (HardieBacker, Schluter): best for wet areas (showers, bathrooms)
  • Existing tiles: can tile over if firmly adhered and level; requires degreasing and keying
  • Wood subfloor: must flex — use decoupling membrane or cement board, minimum 19mm subfloor thickness
  • Use appropriate adhesive: standard set cement for most; rapid-set for heated floors; flexible for wood

How to Calculate Tiles for a Floor or Wall

Three steps to get the right tile count including waste.

  1. 1
    Measure the area
    Measure the room's length and width. For walls, measure each wall separately and add them. For L-shaped rooms, divide into rectangles.
  2. 2
    Enter your tile dimensions and waste factor
    Enter the tile length and width in cm (metric) or inches (imperial). Set the waste factor: 10% for standard straight lay, 15% for diagonal, 20% for complex patterns.
  3. 3
    Enter tiles per box
    This is on the box label. The result shows total tiles needed, exact count, and number of boxes to buy. Buy at least one extra box and store it for future repairs.

FAQ

How much waste should I plan for?
10% is standard for straight layouts. Diagonal patterns = 15%. Complex mosaics or small rooms with lots of cuts = 20%.
Should I buy extra boxes for repairs?
Yes — at least one extra box. Tile manufacturers produce in batches, and colors can shift noticeably between production runs, so matching later is painful.
Do I include grout lines?
Most tile calculators (including this one) ignore grout lines because the tile count accounts for them automatically — you're buying tiles, not coverage.
What size tile is best for small rooms?
Counter-intuitively, large format tiles (60×60 cm or 24×24 in) can make small rooms look bigger by reducing the number of grout lines. But they're harder to lay on uneven floors — the substrate needs to be very flat.

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