Quick answer: Divide the tiled area by the area one tile covers, then add 10% for straight layouts or 15% for diagonal and large-format tiles. A 5 × 8 ft bathroom floor (40 sq ft) with 12 × 24 inch tiles needs 20 tiles, or 23 with 15% extra.
Tile is sold by the piece or by the box, and the number you need depends on the tile size, the grout joint and how many cuts your layout requires. Here is how to work it out for the most common bathroom and kitchen projects.
The Basic Tile Formula
Tiles = Area to tile ÷ Area of one tile
For a more accurate count, add the grout joint to each tile dimension. A 12 × 12 inch tile with a ⅛ inch joint actually covers 12⅛ × 12⅛ inches.
Example 1: Bathroom Floor
- Floor: 5 × 8 ft = 40 sq ft
- Tile: 12 × 24 in = 2 sq ft each
- Tiles: 40 ÷ 2 = 20
- With 15% extra for large-format cuts: 23 tiles
Example 2: Tub Surround
- Back wall: 5 ft wide × 6 ft high = 30 sq ft
- Two end walls: 2.5 × 6 ft = 15 sq ft each, 30 sq ft total
- Total: 60 sq ft
- 3 × 6 in subway tile (8 per sq ft): 480 tiles, or 528 with 10% extra
Example 3: Kitchen Backsplash
A backsplash 12 ft long and 18 inches high is 18 sq ft. Subtract the window or range hood area if it will not be tiled. With 4 × 4 inch tiles (9 per sq ft) you need 162 tiles, or 179 with 10% extra.
Skip the math: enter the area, tile size and grout joint to get tiles, boxes and grout in imperial or metric. Open the free Tile Calculator →
Tiles per Square Foot and Square Meter
| Tile size | Per sq ft | Per m² (approx.) |
|---|---|---|
| 3 × 6 in subway | 8 | 86 |
| 4 × 4 in | 9 | 97 |
| 6 × 6 in | 4 | 43 |
| 12 × 12 in | 1 | 10.8 |
| 12 × 24 in | 0.5 | 5.4 |
| 24 × 24 in | 0.25 | 2.7 |
| 30 × 60 cm | ≈0.52 | 5.6 |
| 60 × 60 cm | ≈0.26 | 2.8 |
How Much Extra Tile?
- 10% for straight layouts in simple rooms.
- 15% for diagonal layouts, large-format tiles or rooms with many cuts.
- 15–20% for herringbone and natural stone.
- Keep a few spare tiles for future repairs.
Grout
Grout use depends on tile size, joint width and tile thickness. Small mosaics with wide joints use far more grout than large tiles with narrow joints. Most grout bags show coverage for common tile sizes, and our calculator estimates it with the formula manufacturers use.
Tips
- Check the box: some tiles are sold by the square foot or square meter, not by the piece.
- Buy from one batch or lot number to avoid shade differences.
- Dry-lay tiles to plan where cuts will fall.
- Tiling walls next to painted ones? See how much paint you need.
Frequently Asked Questions
How many 12×24 tiles do I need for 100 square feet?
Each 12 × 24 tile covers 2 sq ft, so you need 50 tiles, or about 58 with 15% extra.
Should I buy 10% or 15% extra tile?
Buy 10% extra for straight layouts and 15% for diagonal layouts, large tiles or rooms with many cuts.
How many tiles are in a box?
It varies by product. Large tiles may come 2–6 per box and small tiles 20–50 per box. Check the coverage in square feet or square meters printed on the box.
Related Guides
- How to Measure a Room for Flooring (Step-by-Step)
- How Much Paint Do I Need for a Room? (Chart by Room Size)
- How Many Sheets of Drywall Do I Need for a Room?
Try the free Tile Calculator or browse all home improvement calculators.