Tile Calculator

From floor area to boxes on the van

Tiling fails quietly in one place: the last row cuts short because the order was "exact". This page turns a room's dimensions and a tile's size into boxes to buy, with a wastage margin for cuts and breakages on top. The arithmetic is small — divide the floor area by one tile's area, multiply by (1 + wastage), round up, and divide by tiles-per-box — but every one of those steps has a silent failure mode, which is the real reason a calculator earns its keep on a project that bricks cannot redo.

Straight layouts are forgiving; diagonal and herringbone layouts eat tiles in the corners, which is why wastage rises from about 10% to 15% or more once cuts multiply. The tool takes whatever margin your layout needs — the default 10% matches the plain-rectangle case most rooms are.

A worked example, step by step

Problem: a kitchen floor 5 m by 4 m, 30 × 30 cm tiles sold ten to a box, straight layout with 10% wastage.

1. Floor area: 5 × 4 = 20 m².
2. One tile: 0.30 × 0.30 = 0.09 m².
3. Exact count: 20 ÷ 0.09 = 222.222222 tiles.
4. With wastage: 222.2222 × 1.1 = 244.4444 → round up to 245 tiles.
5. Boxes: 245 ÷ 10 = 24.5 → 25 boxes. Order 25.

Every rounding above is upward on purpose: 244.44 is not a purchasable quantity, and 24 boxes cover 240 tiles — four short of the wastage-adjusted need. The panel's "With 10% wastage: 245" line is the number to hand a supplier.

Tile sizes and how many a square metre eats

Formats change the feel of a room faster than they change the order: a floor that takes eleven 30 cm tiles per square metre takes under three 60 cm ones, which shows up in labour time and adhesive line as much as in boxes.

Walls, altitudes and the second room

The same maths covers a splashback or a feature wall: work the wall's area, not the room's. A 2 m × 4 m wall in 40 × 40 cm tiles with 10% wastage needs 8 ÷ 0.16 = 50 → 55 with wastage → 6 boxes of ten — that is the shape of the answer for any wall. And a second, smaller room benefits from the first room's offcuts: big-format leftovers often clear a loo floor completely, which drops the second order's box count by one or two.

Mistakes that quietly strand a tiler

• Zero wastage on a diagonal layout. 10% is the floor for plain work; diagonals and patterns want 15%+ or a re-order mid-job.
• Mixing metres and centimetres. A 30 entered where 0.30 belongs makes tiles the size of rooms; keep room in metres, tile in centimetres, as the fields request.
• Forgetting adhesive and grout. Neither is in this count; both buy in bags roughly per 5 m² of area — check the products' own coverage lines.
• Assuming boxes are staples-proof. Dye-lot variations between batches mean one extra box bought today beats one chased next month.

Keep exploring

• Square Footage Calculator — the same footprint in finished square metres, when quoting by area.
• Wallpaper Calculator — the vertical-surface sibling for the walls above the tiles.
• Paint Quantity Calculator — the room's other finish, with its own coverage arithmetic.
• Guide: Unit Conversion Mistakes to Avoid.