How much tile do I need?
Measure each surface and multiply length by width. Subtract anything you won't tile, like a tub, window or niche. Add 10% for cuts and breakage on a straight or offset layout, and 15% for diagonal or herringbone. Divide by the square feet in a box and round up.
Boxes = (length × width − openings) × (1 + waste %) ÷ sq ft per box
An 8 × 5 ft bathroom floor is 40 sq ft. With 10% waste that's 44 sq ft, which is 44 tiles at 12 × 12 in. At 11 sq ft per box, you buy 4 boxes. A 1/4 × 3/8 in trowel covers about 60 sq ft per 50 lb bag of thinset, so one bag. Grout at 1/8 in joints comes to about 3.3 lb, so one bag.
Thinset coverage by trowel size
| Trowel notch | Typical tile | Sq ft per 50 lb bag |
|---|---|---|
| 3/16 in V-notch | Mosaics | About 100 |
| 1/4 × 1/4 in square | Subway, 4 × 4, 6 × 6 | About 90 |
| 1/4 × 3/8 in square | 12 × 12 in | About 60 |
| 1/2 × 1/2 in square | 12 × 24 in and larger | About 42 |
These are typical figures for modified thinset. Enter the number on your bag; back-buttering large tile uses more.
How much grout do I need?
Smaller tiles mean more joints, so mosaics take far more grout than large tile. Joint depth is the tile's thickness.
Grout (lb per sq ft) = (L + W) ÷ (L × W) × joint width × joint depth × 9.68
Measure everything in inches. This is the standard metric grout formula (× 1.86 for kg per m² in millimeters) converted to pounds and inches. The calculator adds 10% for waste.
| Tile | Joint | Thickness | Grout per 100 sq ft |
|---|---|---|---|
| 2 × 2 in mosaic | 1/16 in | 1/4 in | About 15 lb |
| 3 × 6 in subway | 1/16 in | 5/16 in | About 9.5 lb |
| 12 × 12 in | 1/8 in | 3/8 in | About 7.6 lb |
| 12 × 24 in | 1/8 in | 3/8 in | About 5.7 lb |
Shower tile calculator
Add each wall as its own surface: the back wall and both end walls. Measure from the top of the tub or pan to where the tile stops. A 5 ft tub surround tiled 6 ft high is 5 × 6 + 2 × (2.5 × 6) = 60 sq ft.
In 3 × 6 in subway tile with 10% waste, that's 66 sq ft: 528 tiles, or 6 boxes of 12.5 sq ft. Shower walls go on cement backer board, not standard drywall: 60 × 1.1 ÷ 15 = 4.4, so 5 sheets of 3 × 5 ft. Waterproof the board as the membrane maker specifies.
Backsplash tile calculator
Multiply the length of the counter run by the height to the bottom of the upper cabinets, usually 18 in. A 12 ft run at 18 in is 18 sq ft. Subtract any window. In 3 × 6 in subway with 10% waste, that's 159 tiles, or 2 boxes. For mosaic sheets, pick 2 × 2 in mosaic.
Floor tile calculator
A 12 × 10 ft kitchen in 12 × 24 in porcelain is 120 sq ft, or 132 sq ft with 10% waste: 66 tiles, 9 boxes of 16 sq ft. Tile this size typically needs a 1/2 in square-notch trowel, so plan on 3 bags of thinset. Laying the same floor on a diagonal or in herringbone takes 15% waste.
Ceiling tile calculator
For a drop ceiling, pick a 2 × 2 or 2 × 4 ft panel. The calculator turns off thinset and grout and uses 5% waste. A 12 × 10 ft room is 120 sq ft, or 126 sq ft with waste: 32 panels of 2 × 2 ft, which is 3 cartons of 12. It's a rough count: centering the grid so the border panels match can add a row. Main tees, cross tees and wall angle are a separate purchase.
Pricing a tile job
Tile setters usually price setting by the square foot and list prep as separate lines: demo, backer board, waterproofing, leveling. Mosaics, subway tile and shower walls take longer per square foot than large floor tile. Switch to contractor mode to add labor and markup, then send it with the estimate template.
Questions
How much tile do I need for a 10 × 10 room?
100 sq ft plus 10% waste is 110 sq ft. That's 110 tiles at 12 × 12 in, or 10 boxes if each box holds 11 sq ft. Use 15% waste for a diagonal layout.
How much extra tile should I buy?
Typically 10% for a straight or offset layout and 15% for diagonal or herringbone. Add more for small rooms with lots of cuts, and keep a few spare tiles for repairs.
How many tiles are in a box?
It depends on the tile and the brand. Boxes are labeled with square feet per box and often the piece count. Enter the number from your box label.
Should I use sanded or unsanded grout?
Unsanded grout for joints under 1/8 in, sanded grout for joints 1/8 in and wider. Check the tile maker's advice for polished stone and glass.
How much thinset do I need?
A 50 lb bag typically covers about 90 sq ft with a 1/4 in square trowel, 60 sq ft with 1/4 × 3/8 in, and 40 to 45 sq ft with a 1/2 in trowel. Check the bag for your brand.