Tile Calculator
Use this tile calculator to find how many tiles you need for a floor, wall or backsplash. Enter the room size (or a known area, with cut-outs subtracted), the tile size and the grout joint width, then choose a waste allowance. It counts tiles with their joint spacing, adds waste, and converts to boxes and cost when you enter tiles per box and a price.
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Area to tile
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Tiles needed (joints included)
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Tiles with waste
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Boxes needed (rounded up)
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Estimated cost
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Each tile is counted with its grout joint: tiles = area ÷ ((tile width + joint) × (tile length + joint)), rounded up. Waste is then added and rounded up again. 10% for a straight layout and 15% for diagonal or complex layouts are typical starting points, and you can adjust them; use more for many cuts, patterns or irregular rooms. This is an area estimate and does not model your exact layout. Grout and thinset needs depend on tile size, tile thickness and joint width, so use the coverage printed on the product bag.
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How it works
- How many tiles do I need?
- Divide the area by the area one tile takes up including its joint, then round up. A 10 ft × 12 ft room is 120 sq ft. With 12 in × 12 in tiles and no joint that is 120 tiles. With a 1/8 in joint each tile takes 12.125 × 12.125 in = 1.021 sq ft, so 120 sq ft needs 118 tiles before waste.
- How much extra tile should I buy for waste?
- 10% extra is a typical starting point for a straight layout and 15% for a diagonal or complex one; use more for many cuts, patterns or irregular rooms. For the 118 tiles above, 10% is 130 tiles and 15% is 136. The slider sets the percentage and you can change it freely.
- Does the grout joint change the number of tiles?
- Yes, a little. Each joint adds to the space a tile takes up, so you need slightly fewer tiles than area ÷ tile area. For 12 in tiles with a 1/8 in joint that is 118 instead of 120, about 2% fewer. The effect is larger with small tiles and wide joints. Set the joint to 0 to ignore it.
- How do I convert tiles to boxes?
- Enter the number of tiles per box. The calculator divides tiles with waste by tiles per box and rounds up. For example, 130 tiles at 10 per box is 13 boxes. If the box label gives square feet instead, divide that by the area of one tile (a 12 in × 12 in tile is 1 sq ft).
- How much grout and thinset do I need?
- It depends on tile size, tile thickness, joint width and trowel notch, so there is no single figure. Check the coverage printed on the bag or the manufacturer's guide for your products, and use the area you are tiling. Smaller tiles and wider joints generally need more grout.