Tile Calculator - How Many Tiles Do I Need?

How the tile calculator works

The calculator divides total room area by the effective area of one tile (tile dimensions plus grout gap on each side). It then applies your waste percentage and rounds up to the nearest whole tile and box.

Waste factor

Always order more tiles than you calculate you need. A 10% waste factor is standard for straight-lay patterns. Use 15–20% for diagonal, herringbone, or intricate patterns where more cuts are required. Extra tiles are also useful for future repairs.

Multiple rooms

If you're tiling several rooms or areas with the same tile, add each area using the Add Room button. The calculator sums all room areas and gives a single total tile count.

Grout gap

The grout gap is typically 1.5–3 mm for floor tiles and up to 6 mm for larger format tiles. Check the tile manufacturer's recommendation for the correct joint width.

Tile layout patterns and waste

Thinset and mortar

In addition to tiles, plan for thinset mortar to bond them to the substrate. A standard 50 lb bag of thinset covers approximately 40–60 sq ft with a 3/16” notched trowel. Larger tiles (12”+) or uneven substrates require more thinset. Always use unsanded grout for joints under 1/8” and sanded grout for wider joints.

Estimating grout quantity

Use the following formula to estimate kilograms of grout needed:

Grout (kg) = ((L + W) / (L × W)) × J × D × 1.8 × Area

Where L = tile length (mm), W = tile width (mm), J = joint width (mm), D = tile depth (mm), 1.8 = grout density factor, and Area = total coverage area (m²).

As a rough rule of thumb, a standard 1 kg bag of grout covers approximately 3–5 m² for 30×30 cm tiles with a 3 mm joint, or about 1–2 m² for small mosaic tiles with wider joints.

Tile adhesive types