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Floor and tile calculator (boxes)

Find out how many boxes of flooring or tile to buy for a room, including waste margin.

m²
m²/box
%
Boxes needed
11
Area with waste22 m²
Purchased area22 m²

The waste margin (10% standard) covers cuts and breakage. Diagonal layouts need 15%.

Interactive lesson: The room doubled. The floor quadrupled, the paint did not. Double a room's dimensions: the floor quadruples and the paint only doubles. See what each change really costs.

How the calculation works

To know how many boxes of flooring or tile to buy, take the area to cover, add a waste margin (cuts and breakage) and divide by the coverage per box — always rounding up, since you can't buy half a box.

boxes = ceil[ area × (1 + waste%) ÷ m² per box ]

Step-by-step example

A 30 m² floor, box covering 2.3 m², 10% waste:

  • With waste: 30 × 1.10 = 33 m²
  • Boxes: 33 ÷ 2.3 = 14.3 → 15 boxes

Examples

  • 20 m², 2 m² box, 10% waste: 22 ÷ 2 = 11 boxes.
  • Diagonal layout: use 15% waste instead of 10%.

Frequently asked questions

How much waste to consider?

10% for straight layout and 15% for diagonal or rooms with many cuts.

Why buy an extra box?

To keep a spare — the same color and batch may be discontinued, and you may need to replace a broken piece years later.

Same math for floor and wall tile?

Yes, same area ÷ coverage logic. For walls, add each wall's area and subtract openings.

How much extra flooring should I buy?

10% for straight laying, 15–20% for diagonal patterns, large tiles or rooms with many cuts.

Why buy all tiles from the same batch?

Because shade and calibre vary between production runs, causing visible colour patches and misaligned joints.

Can I lay tiles without grout joints?

Not advisable. Joints accommodate thermal expansion and calibre variation; without them tiles can buckle and detach.

What is the PEI rating?

It rates abrasion resistance from 1 to 5. Home bathrooms need PEI 3; high-traffic commercial areas PEI 5.

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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources