How to use it
- Choose Floor or Walls and enter the room size in feet.
- Enter the tile size in inches and the coverage per box.
- Pick a waste allowance (10% is typical).
- Set the grout joint and bag sizes and read the materials list.
How the tile count is calculated
Floor: area = length × width. Walls: area = 2 × (length + width) × tile height, minus doors, windows and the area behind a tub.
Tiles needed = area × (1 + waste %) ÷ area of one tile, rounded up. Boxes = area with waste ÷ coverage per box, rounded up.
Example: a 10 × 8 ft bathroom floor is 80 sq ft. With 10% waste you need 88 sq ft. A 12 × 24 in tile covers 2 sq ft, so that's 44 tiles; at 16 sq ft per box, 6 boxes (96 sq ft).
How much waste to allow
| Layout | Waste allowance |
|---|---|
| Straight lay, large room, few cuts | 5% |
| Typical room | 10% |
| Diagonal, herringbone, many corners, small room | 15% |
Large-format tiles and patterned layouts produce more offcuts. Add more if you're new to tiling. Buy an extra box if you're not sure you'll find the same production lot later: shade and size can vary between lots, and a spare tile is invaluable when one cracks.
Thinset and grout
Thinset mortar depends mostly on the trowel notch. Check the bag; as a rough guide, a 50 lb bag covers about 90–100 sq ft with a 1/4 in square notch, and about half that with the 1/2 in notches used for large tiles. Enter the coverage per bag and the bag size; the calculator gives pounds and bags.
Grout is estimated with the manufacturers' formula: (A + B) ÷ (A × B) × tile thickness × joint width × density, where A and B are the tile sides. Narrow joints and big tiles need little grout; small mosaics with wide joints need much more. Enter the joint width (1/8 in = 0.125, 1/16 in = 0.0625) and tile thickness (3/8 in = 0.375).
Base tile and cost
For floors, tick Also calculate base tile to get the linear feet of cove or bullnose base around the room, minus one 3 ft doorway, plus 10% for cuts. Enter the price per sq ft to see the cost of the boxes you'll buy (or of the area, if you leave box coverage empty).
If you're laying laminate or vinyl plank instead, use the flooring calculator, which also handles underlayment and baseboard.
Measuring tips
- Measure to the walls, not to existing baseboards, and round up.
- For an L-shaped room, split it into two rectangles and add the areas, or run the calculator twice.
- Tile sizes are nominal: a "12 × 24" tile may actually be 11 3/4 × 23 1/2 in. Use the coverage printed on the box for the box count.
- For walls, measure only up to where the tile stops (for example 7 ft in a shower, 4 ft for a wainscot).
Frequently asked questions
How many tiles do I need for 100 square feet?
With 12 × 12 in tiles and 10% waste, 110 tiles. With 12 × 24 in tiles, 55. Use the box coverage to know how many boxes to buy.
How much extra tile should I buy?
10% for a typical room, 15% for diagonal or herringbone layouts and rooms with many corners, 5% for simple large rooms.
How many bags of thinset do I need?
Divide the area by the coverage on the bag. A 50 lb bag commonly covers about 90–100 sq ft with a 1/4 in notch trowel, less with larger notches.
How much grout do I need?
It depends on tile size, thickness and joint width; the calculator uses the standard manufacturer formula. Large tiles with 1/8 in joints need only a few pounds per 100 sq ft.
Does the calculator handle wall tile?
Yes. Choose Walls, enter the room size and tile height, and subtract doors, windows and the tub area.
Last updated: November 12, 2026