Calculating Tile Quantity and Wastage Before You Buy

Two problems come up again and again on site. Either the client is a few boxes short when the last room is half done, or there are many boxes left over at the end. The first is worse: the dealer may not have the same batch any more, and new tiles from a different batch can be a slightly different shade or size. Calculating tile quantity and wastage before you buy avoids both problems.

Here is the method we use when clients ask us to check their tile order.

Step 1: Measure each area separately

Do not estimate the whole house in one figure. Measure each room, bathroom, kitchen, balcony and staircase separately, because each may use a different tile and layout.

• Measure length and width of each room at floor level, wall to wall.
• For rooms that are not rectangular, divide them into rectangles and add them up.
• Note recesses, wardrobes, door openings and passages where tiles continue.
• Take measurements in feet or metres, but be consistent with how the tile box area is given.

Step 2: Calculate floor area

Floor area is simply length multiplied by width for each rectangle. Add the rectangles together for the total area of that room.

Example: a bedroom measuring 12 ft by 14 ft has a floor area of 168 sq ft. If there is an attached dressing area of 5 ft by 6 ft, add 30 sq ft, making 198 sq ft.

Should you subtract the area under fixed wardrobes or kitchen cabinets? If the cabinets are not yet fixed, we usually recommend tiling under them, so do not subtract. It keeps options open if furniture changes later.

Step 3: Calculate wall area

For bathroom and kitchen walls, measure the length of each wall and the height up to which tiles will go.

• Wall area = wall length multiplied by tiling height.
• Subtract doors and windows only if they are large. Small openings are better left in as a safety margin, since the cuts around them create waste anyway.
• Add the window reveals (the side and top faces of the opening) if they are being tiled.

Step 4: Calculate skirting

Skirting is measured in running length, not area. Add up the perimeter of the room and subtract door openings. Then work out how many skirting pieces you can cut from one tile. For example, if skirting is cut from floor tiles, a single tile may give two or more strips depending on the tile size and skirting height. Divide the running length by the length of strips to find how many tiles you need.

Step 5: Add wastage based on layout and tile

Wastage covers cuts at walls, breakage during transport and cutting, and spare tiles for future repairs. The amount depends on the layout and the room.

These are general working margins. Your fitter should check them against the actual room and tile size.

Step 6: Convert to boxes

Tiles are sold by the box, and each box states the area it covers. Divide your total area including wastage by the coverage per box, and always round up to the next whole box.

Example: the bedroom above at 198 sq ft with 8 percent wastage needs about 214 sq ft. If one box covers 15.5 sq ft, you need 214 divided by 15.5, which is about 13.8, so order 14 boxes.

Check the box label rather than assuming. Box coverage depends on tile size and the number of tiles per box, and it varies between brands.

How tile size affects wastage

Larger tiles reduce the number of joints, but in small rooms they can create more waste because cut pieces cannot be reused elsewhere. Smaller tiles allow offcuts to be used along the other wall. For large-format tiles, plan the layout on a drawing before ordering so you know exactly how many full and cut pieces are needed.

Batch and shade: order once

• Order the full quantity in one go, from the same batch.
• Check the batch and shade codes on every box when the delivery arrives.
• Keep a few spare tiles after the job, labelled with the batch, for future repairs. If a tile cracks in five years, a matching spare saves the whole floor.

Staircases and special areas

For stairs, count treads and risers as separate pieces rather than area. Each tread usually needs one full tile or a step tile, and each riser a cut strip. Landings are calculated as floor area. Kitchen dado, niches, shelves and pujaghar walls are small areas with many cuts, so add a more generous margin there.

Do not forget the other materials

While calculating tiles, also plan adhesive, grout, spacers or levelling clips, and any edge trims or nosings. Running out of grout of the chosen colour mid-job causes the same shade mismatch problem as tiles.

Tile quantity checklist

1. Each area measured separately and noted.
2. Floor, wall and skirting quantities calculated separately.
3. Wastage added according to layout and room shape.
4. Converted to boxes using the actual box coverage, rounded up.
5. Full order from one batch, shade codes checked on delivery.
6. Spare tiles kept after fitting.

Let us check your numbers

If you share your floor plan, room sizes and chosen tile size, we can check your quantity and suggest the layout before you place the order. It is a small step that often saves money and avoids shade problems. WhatsApp the details to 9468916422, see our tile fitting and flooring service, or use the contact page.