Tile Calculator

Tiling is one of the most rewarding home improvement projects you can undertake — a well-tiled floor, backsplash, or shower transforms a space instantly and adds lasting value to your home. But before a single tile is set, you need to know exactly how many tiles to buy. Under-order and you risk running out mid-project; over-order and you're left with expensive surplus material. The Tile Calculator gives you an accurate count of tiles needed for any rectangular area, automatically accounting for grout joints and a user-defined waste percentage.

The first step is measuring your area accurately. For floors, measure the length and width of the room at the widest points, including any alcoves or closets you plan to tile. For backsplashes, measure the width and height of each section independently, then sum them. For showers, measure each wall face separately. Irregular shapes should be broken into rectangles, calculated individually, and totalled.

Tile size has a major impact on how many individual tiles you need. A 12×12 inch tile and a 24×24 inch tile cover very different amounts of area — the larger tile covers four times the surface with just one tile. Larger format tiles (18×18, 24×24, even 48×48 inches) are increasingly popular in modern design because they create a seamless look with fewer grout lines, though they require a flatter substrate and more careful installation.

Grout joint width is a detail many DIYers overlook when calculating quantities, but it matters. A standard 1/8-inch (3 mm) grout joint on a 12×12 tile adds only about 1% to each tile's effective footprint, but on small mosaic tiles or wide-joint applications the cumulative difference becomes meaningful. This calculator incorporates the grout gap into the effective tile dimensions to give you a precise result.

Waste percentage accounts for tile cuts at edges and corners, breakage during cutting, tiles rejected for cosmetic defects, and future repair stock. As a rule of thumb: 10% is standard for simple rectangular rooms with straight-lay patterns; 15% is appropriate for diagonal (45°) or herringbone layouts, which require significantly more cuts; 20%+ is recommended for complex patterns, irregularly shaped rooms, small mosaic tiles, or natural stone tiles with higher breakage rates. Never drop below 5% even on the simplest projects — breakage during cutting is inevitable.

When purchasing, note that tiles are sold in boxes covering a stated square footage. Divide your total required area (including waste) by the box coverage to determine how many boxes to buy, always rounding up. Keep at least 5–10% of your tile purchase in storage even after the project is complete — tiles get discontinued, and a matching replacement years later is often impossible to find.

Professional installers also recommend purchasing all tiles from the same dye lot (production batch) to ensure colour consistency. Even tiles with the same product name can have subtle shade variations between lots. Check that all boxes share the same lot number when buying.

This calculator is designed for rectangular areas. For L-shaped rooms, calculate each rectangle separately and add the totals. For curved or circular areas, use the area formula for your shape (π × r² for a circle) and divide by your tile area to get a count, then add waste.