Tile Calculator
Calculate how many tiles you need for a floor, wall or backsplash, including grout lines and waste, with boxes and cost
Last updated: November 2, 2026
How to Use the Tile Calculator
How to calculate how many tiles you need
- Measure the area. Enter the length and width of the floor in feet. For a wall, use its width and height. For several areas, calculate each and add the tile counts.
- Enter the tile size. Type the tile width and length in inches. Common sizes are 12 x 12, 12 x 24 and 6 x 24.
- Set the grout joint. The default 1/8 inch (0.125) suits most floor tiles. Use 0 to ignore it.
- Choose the waste allowance. Keep 10% for simple layouts or raise it for diagonal or patterned layouts.
- Add box size and price (optional). Open Advanced options to see the number of boxes and a cost estimate.
Subtract large permanent features such as a kitchen island or bathtub from the area before you enter it.
Formula & Methodology
Tile quantity formula
Tiles = Area ÷ Area of one tile (including the grout joint)
The area of one tile with its share of grout is (tile width + joint) × (tile length + joint), all in inches. Convert the room area from square feet to square inches by multiplying by 144.
Tiles to buy = Tiles × (1 + Waste %), rounded up to a whole tile.
Worked example
A room is 12 ft × 10 ft and you are using 12 in × 12 in tiles with 1/8 in grout joints and 10% extra for waste.
- Area = 12 × 10 = 120 sq ft = 120 × 144 = 17,280 sq in
- One tile with grout = (12 + 0.125) × (12 + 0.125) = 147.02 sq in
- Tiles for the area = 17,280 ÷ 147.02 = 117.5
- With 10% waste = 117.5 × 1.10 = 129.3, so buy 130 tiles
Why add waste?
You will cut tiles to fit around the edges, corners, doors and fixtures, and some will chip or break. About 10% covers a straightforward layout. Use 15 to 20% for diagonal or herringbone layouts, small tiles, or rooms with many corners.
Boxes
Tiles are sold in boxes. Divide the number of tiles by the number in a box and round up. It is also wise to keep a few spare tiles from the same batch for future repairs, because colors can vary between batches.
About Tile Calculator
Our tile calculator is a free, easy-to-use tool designed to help youcalculate how many tiles you need for a floor, wall or backsplash, including grout lines and waste, with boxes and cost. For professionals or those who need quick calculations, our calculator provides accurate results instantly.
Frequently Asked Questions
How do I calculate how many tiles I need?
Work out the area in square inches (square feet × 144), divide by the area of one tile including its grout joint, and add 10% for waste. A 12 ft by 10 ft room with 12 in tiles needs about 130 tiles with a 1/8 in grout line.
How much extra tile should I buy?
Ten percent is the usual allowance for a simple straight layout. Buy 15 to 20% for diagonal, herringbone or other patterned layouts, small mosaic tiles, or rooms with lots of corners and cuts.
Does the grout joint change the number of tiles?
Slightly. Wider joints mean each tile covers a bit more area, so you need fewer tiles. The effect is small for narrow joints but noticeable with small tiles or wide grout lines. Enter your joint width, or 0 to ignore it.
How do I measure the area for tile?
Multiply the length by the width in feet. For an L-shaped room, split it into rectangles and add their areas. Subtract any areas you will not tile, such as a bathtub or a kitchen island.
How many 12x12 tiles are in a square foot?
Exactly one, ignoring grout. A 12 inch by 12 inch tile covers 144 square inches, which is one square foot. For 12 x 24 tiles, one tile covers 2 square feet.
Should I round up to full boxes?
Yes. Tiles are sold in boxes, so round up to the next whole box. Keeping a few spare tiles is useful for repairs later, since the same tile from a different production batch can vary slightly in color.
Can I use this for wall tiles or a backsplash?
Yes. Enter the width and height of the wall or backsplash area in feet instead of a floor length and width. Subtract any windows or outlets if they are large.
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