Tile Calculator

How many tiles do I need?

The core of a tile estimate is dividing the floor (or wall) area by the area of a single tile. The catch is that tiles are measured in inches or centimeters while the room is in feet or meters, so the units have to be matched first. This tool handles the conversion, adds a waste allowance, and rounds up to whole tiles and boxes.

The formula

• Floor area = length × width of the space.
• Tile area = tile width × tile height, converted to the same units. A 12 × 12 inch tile is exactly 1 square foot; a 30 × 30 cm tile is 0.09 square meters.
• Tiles needed = floor area ÷ tile area, then × waste factor, rounded up.

Why a waste allowance matters

Tiles at the edges of a room must be cut, and every cut risks a crack or a piece that's too small to use. A 10% allowance is the usual minimum for a straight grid layout. Bump it to 15% for a diagonal layout, a room with lots of corners or alcoves, or large tiles where one bad cut wastes a lot. Buying a few extra is also cheap insurance for future repairs — dye lots change, and a matching replacement years later is nearly impossible.

Buy by the box, keep the dye lot

Tiles ship in boxes of a fixed count, so the tool rounds your total up to whole boxes. Try to buy all your tile in one order: tiles from the same dye lot (batch) are guaranteed to match, while a later box can be subtly off in shade or size.

FAQ

Does this work for a backsplash or shower wall?

Yes — any flat rectangular surface. Enter the wall's length and height instead of floor dimensions. For a backsplash, measure the run of counter and the height up to the cabinets.

Should I account for grout lines?

Grout lines slightly reduce the number of tiles needed, but the effect is small and the waste allowance more than covers it. It's safer to ignore grout in the count and keep the buffer.

How much waste allowance should I add?

A 10% allowance is the usual minimum for a straight grid layout. Bump it to 15% for a diagonal layout, a room with many corners or alcoves, or large-format tiles where one bad cut wastes a lot. The extras also serve as spares for future repairs.

Why does it round up to whole boxes?

Tile is sold in boxes of a fixed count, not as loose pieces, so the tool rounds your total up to the nearest full box. Buying it all in one order also keeps every tile in the same dye lot, which guarantees the shade and size match.

Can I calculate for multiple rooms at once?

Calculate each room or surface separately, since waste and box rounding apply per area, then add the box totals. If two rooms use the exact same tile, you can also add their areas first and apply one waste allowance to the combined figure.

Is this tile calculator free, and does it work on mobile?

Yes, it is completely free with no sign-up, runs entirely in your browser so nothing you enter is uploaded, and works on phones, tablets, and desktops, which is handy when measuring at the store or job site.