Tile Coverage Calculator
Calculate the number of tiles you need for any floor or wall, including grout joint spacing and a waste factor.
Tile is unforgiving of miscalculation, running short mid-floor means a second order that may be from a different production batch and won't match perfectly. I always add 10% minimum, and 15% for diagonal patterns which waste significantly more at the edges.
Buy all your tile at once from the same lot number. Tile color and texture vary between production batches, tiles from a second order may not match even if the SKU is identical.
How tile quantity is calculated
Total area divided by tile area gives the number of tiles before waste. The grout joint adds to the effective tile spacing, a 12×12 tile with a 1/8" grout joint occupies 12.125×12.125 inches of floor. For most calculations this difference is small, but for very large tiles or wide grout joints it becomes meaningful. Always add a waste factor for cuts at walls, around obstacles, and breakage.
Diagonal tile patterns
Diagonal installation (45° to the walls) looks striking but wastes significantly more tile. At the perimeter, every tile must be cut at 45°, creating triangular waste pieces that can rarely be used elsewhere. Add 15% minimum for diagonal patterns; 20% for complex spaces with many corners, cutouts, and fixtures.
Grout joint sizing
Grout joint width depends on tile type and design preference. Rectified tiles (precision-cut, consistent dimensions) can be installed with joints as small as 1/16". Standard tiles typically need 1/8"–3/16" to accommodate slight size variation. Large-format tiles (18"+ or 24"+) often look best with minimal joints. Wider joints (1/4"+) give a more traditional look and are more forgiving of slight irregularities.
Tile setting materials
Tile requires thinset mortar (not mastic for wet areas or large tiles), grout, and spacers. For floors, use unsanded grout for joints under 1/8" and sanded grout for joints 1/8" and larger. Bathroom and kitchen tile should use polymer-modified thinset rated for wet areas. Calculate thinset at approximately 50 sq ft per bag and grout at the coverage listed on the bag (varies by joint size and tile type).
Frequently asked questions
What tile size is best for small rooms?
Contrary to old advice that small rooms need small tiles, large-format tiles (12×24 or 24×24) can make small rooms appear larger by reducing the number of grout lines. The key is ensuring the layout looks balanced, avoid narrow cut pieces at the walls by centering the layout and adjusting from there.
Can I tile over existing tile?
Sometimes. The existing tile must be well-adhered, level, and able to support the additional weight. The total thickness adds to the floor height, which may create transitions to adjacent rooms. New tile over old tile is not recommended for floors with flex (bounce), the movement will crack grout joints and potentially tiles. Consult local building code for your specific situation.
How do I handle cuts around toilets, fixtures, and cabinets?
Plan the layout before cutting any tile. Mark the center of the room or the most visible straight line and work outward. Cuts at the walls should be as similar on both sides as possible, avoid having a narrow sliver on one side and a full tile on the other. Toilet flanges and fixture cutouts require a wet saw, jigsaw with tile blade, or angle grinder with a diamond blade.