A tiled floor needs more than tile. Plan for thin-set mortar (a 50 lb bag covers roughly 90 to 100 sq ft with a ¼ × ¼ in square-notch trowel), grout, a substrate such as cement backer board where the floor needs one, plus screws, mesh tape, spacers and often a sealer. For a 100 sq ft floor with 12 × 12 in tile, that typically means about 110 tiles, two bags of thin-set, one or two bags of grout and seven or eight sheets of 3 × 5 ft backer board.
Our tile calculator counts the tiles and boxes, and the grout calculator estimates grout. For mortar, the thinset calculator uses the coverage chart below.
What materials do you need to install tile?
| Material | What it does | How it is sold |
|---|---|---|
| Tile | The finished surface | Boxes, by square feet or pieces |
| Thin-set mortar | Bonds tile to the substrate | 50 lb bags (powder) or premixed tubs |
| Grout | Fills the joints between tiles | Bags by weight, or premixed |
| Backer board or underlayment | A stable, moisture-tolerant base | Sheets, often 3 × 5 ft (15 sq ft) |
| Backer screws and mesh tape | Fasten and tape the board seams | Boxes and rolls |
| Spacers and leveling clips | Keep joints even and tiles flat | Bags |
| Sealer (some grouts and stones) | Reduces staining | Bottles |
| Tools | Trowels, float, sponges, mixing paddle, cutter or wet saw | Buy or rent |
Thin-set: how much do you need?
Thin-set coverage depends on the trowel notch, and larger tiles need larger notches. For one widely sold product, Custom Building Products’ VersaBond, the published coverage per 50 lb bag is:
| Trowel notch | Coverage per 50 lb bag |
|---|---|
| ¼ × ¼ × ¼ in square-notch | 90 to 100 sq ft |
| ¼ × ⅜ × ¼ in square-notch | 60 to 67 sq ft |
| ¾ × 9/16 × ⅜ in U-notch at 30° | 42 to 47 sq ft |
| ¾ × 9/16 × ⅜ in U-notch at 45° | 34 to 38 sq ft |
Back-buttering large tiles and setting the backer board in thin-set as well both use extra mortar, so most people buy one more bag than the floor area alone suggests.
Grout: why small tiles use much more
Grout fills the joints, so the amount depends on how many feet of joint there are per square foot of floor, plus the joint width and tile thickness. Small tiles have far more joint:
| Tile size | Joint length per sq ft of floor | Compared with 12 × 12 |
|---|---|---|
| 24 × 24 in | 1 ft | Half |
| 12 × 24 in | 1.5 ft | 75% |
| 12 × 12 in | 2 ft | Baseline |
| 6 × 6 in | 4 ft | 2× |
| 3 × 12 in subway | 5 ft | 2.5× |
Grout makers publish coverage calculators that take tile size, thickness and joint width; use one for the bag count.
How to estimate material quantity and waste
- Measure the floor and add your tile waste allowance; see tile layout patterns and waste.
- Choose the trowel notch for your tile size and look up thin-set coverage; divide the area by it and round up.
- Estimate grout from the tile size, joint width and thickness with the grout maker’s calculator.
- Divide the area by the backer board sheet size and add a sheet or two for cuts.
- Add screws, mesh tape, spacers, sealer and tool rental.
A sample tile installation budget
For a 100 sq ft floor with 12 × 12 in tile. Prices are made-up examples to show the method, not current prices.
| Line | Quantity | Unit price | Total |
|---|---|---|---|
| Tile, 10 sq ft per box (110 sq ft with waste) | 11 boxes | $40 | $440 |
| Thin-set, 50 lb | 2 bags | $28 | $56 |
| Grout | 1 bag | $22 | $22 |
| Cement backer board, 3 × 5 ft | 8 sheets | $14 | $112 |
| Backer screws and mesh tape | 1 lot | $30 | $30 |
| Grout sealer | 1 bottle | $18 | $18 |
| Materials subtotal | $678 | ||
| With 7% sales tax | $725.46 | ||
| With 10% contingency | $798.01 |
Tile is about two thirds of this budget; everything else is the other third. That share is why budgets that price only the tile fall short.
DIY vs professional installation
- DIY saves labor but adds tool costs (a wet saw or cutter, mixing paddle, trowels) and time.
- Large-format tile, natural stone, showers and anything needing waterproofing reward experience.
- Ask installers whether their quote includes materials, substrate repairs, removal of old flooring and disposal, so you compare like with like.
The project material cost calculator adds your lines with tax, delivery and contingency; see also how to estimate DIY project costs.
Sources
- Custom Building Products: VersaBond Professional Tile Mortar (thin-set coverage per 50 lb bag by trowel size)
