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Tile Flooring & Overage Calculator

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Work out how much tile to buy for a room. Enter the floor size, the tile size and how much one box covers, add extra for cuts and pattern, and get the boxes to buy, the number of tiles and the cost.

By the CalcKite team · Last reviewed 19 Oct 2026 · Formula · Cite · Embed

Tile Flooring & Overage Calculator

Calculate how many tiles and boxes you need for a floor, with extra for cuts and waste, areas to leave out and the total material cost.

Floor area = length × width − areas left out Area to buy = floor area × (1 + waste %) Boxes = area to buy ÷ coverage per box, rounded up Tiles = area to buy ÷ area of one tile, rounded up

Example: A 10 × 10 ft room with 12 × 12 inch tiles. Floor area: 100 sq ft; With 10% extra: 110 sq ft; Boxes covering 20 sq ft: 110 ÷ 20 = 5.5, rounded up: 6 boxes; Tiles: 110 tiles; Cost at $45 a box: $270.

Understand the resultHow it works, worked example, formula and FAQ
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How to use the Tile Flooring & Overage Calculator

Choose feet or metres and enter the room’s length and width. Subtract areas you won’t tile, such as cabinets or a tub. Enter the tile size (inches or cm) and how much one box covers, from the box label. Set the extra for waste: about 10% for a straight layout, 15% for diagonal and 20% for herringbone. The green box shows the boxes to buy.

Worked example

A 10 × 10 ft room with 12 × 12 inch tiles

Floor area100 sq ft
With 10% extra110 sq ft
Boxes covering 20 sq ft: 110 ÷ 20 = 5.5, rounded up6 boxes
Tiles110 tiles
Cost at $45 a box$270

Assumptions and limits

  • Rooms are treated as rectangles; split L-shaped rooms into rectangles and add them up.
  • Waste covers cuts at the edges and breakage. Complex patterns need more.
  • Grout, thinset, underlayment and trim aren’t included.

Formula

Floor area = length × width − areas left out Area to buy = floor area × (1 + waste %) Boxes = area to buy ÷ coverage per box, rounded up Tiles = area to buy ÷ area of one tile, rounded up

Frequently asked questions

How much extra tile should I buy?

About 10% for a straight layout, 15% for diagonal and 20% or more for herringbone or large tiles in small rooms. Keep a few spares for future repairs.

How do I measure a room for tile?

Measure the length and width at the widest points and multiply. For odd shapes, split the room into rectangles, work out each area and add them up.

Cite or link to this calculator

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CalcKite. (2026). Tile Flooring & Overage Calculator [Online calculator]. https://www.calckite.com/tile-flooring-calculator/

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