Tile Calculator
Work out how many tiles and boxes you need for your project, based on your room size, tile size, grout gap, and a waste allowance.
Your tile estimate will appear here
Enter your room and tile dimensions, then click calculate to see how many tiles and boxes you'll need.
Quick Answer
To find the number of tiles needed, divide your room's area by the area of one tile (including the grout line), then add a waste allowance of around 10% for cuts and breakage. Divide the result by the tiles per box to get the number of boxes.
How It Works: Formula & Variables
Tiles Needed = (Room Area ÷ Tile Area) × (1 + Waste % ÷ 100)
- Room Area
- Length × width of the room, or entered directly if you already know the square footage.
- Tile Area
- Tile width × tile length, with the grout line width added to each side.
- Waste %
- Extra tiles bought to cover cuts, breakage, and future repairs — commonly 10%.
- Boxes Needed
- Tiles needed ÷ tiles per box, rounded up to the next whole box.
Worked Examples
Example 1: Bathroom floor in feet and inches
A bathroom floor is 8 ft × 10 ft (80 sq ft), tiled with 12x12 inch tiles and a 1/8 inch grout line. Each tile covers just over 1 sq ft, so you need roughly 80 tiles before waste. Adding 10% waste brings that to about 88 tiles. If tiles come in boxes of 10, that's 9 boxes.
Example 2: Kitchen floor in meters and centimeters
A kitchen floor is 4 m × 3 m (12 m²), tiled with 30x30 cm tiles. Each tile covers 0.09 m², so you need about 133 tiles before waste. With a 10% waste allowance, that's about 147 tiles, or 15 boxes if each box holds 10 tiles.
Key Concepts
Waste allowance: Cutting tiles to fit around edges, corners, and fixtures always produces some unusable offcuts. Buying extra avoids a second trip to the store if a tile breaks later.
Grout line width: The grout line adds a small amount to each tile's effective footprint, which can slightly increase the total tile count for large areas.
Box coverage: Tiles are usually sold by the box, not individually. Always round up to the next full box, since stores rarely sell partial boxes.
Pattern complexity: Diagonal, herringbone, and other intricate layouts produce more offcuts than a simple grid, so they need a larger waste allowance.
Common Mistakes
Skipping the waste allowance: Ordering the exact number of tiles needed often leaves you short once cuts and breakage are accounted for.
Mixing units: Entering room dimensions in feet but tile sizes in centimeters (or vice versa) will throw off your tile count. Use the unit toggle to keep everything consistent.
Ignoring grout lines: For large rooms with many tiles, ignoring the grout line width can lead to a noticeable undercount.
Rounding down on boxes: Always round up to the next full box. Buying one box short can mean a delayed project waiting on a reorder, sometimes from a different dye lot.
Frequently Asked Questions
Divide the area of your room by the area of one tile (including the grout line), then add 10% extra for cuts, waste, and breakage. For example, a 100 sq ft room with 12x12 inch tiles needs about 100 tiles, plus 10 extra, so 110 tiles.
Most installers recommend adding 10% extra for straightforward rectangular rooms. For diagonal layouts, herringbone patterns, or rooms with lots of corners and cuts, 15-20% extra is safer.
First calculate the total number of tiles needed (including waste), then divide by the number of tiles per box and round up. If you need 110 tiles and each box contains 10 tiles, you need 11 boxes.
Yes, slightly. A wider grout line increases the effective footprint of each tile, which can reduce the number of tiles that fit in a given area. For most home projects this effect is small, but it matters more for large rooms or thick grout lines.
Use the unit toggle on this calculator to switch between feet/inches and meters/centimeters. The calculator handles the conversion automatically so your tile count stays accurate either way.