🔲 🔲 Tile Calculator: How Many Tiles Do You Need?

Running out of tiles halfway through a bathroom floor — especially with custom or discontinued tiles — is a costly, stressful mistake. Getting the count right before you buy requires measuring the space, knowing your tile size, and adding the right percentage for waste and cuts. Here's everything you need to calculate tile quantities accurately.

The Tile Calculation Formula

Number of tiles = Total room area ÷ Area of one tile

Then add a waste percentage on top.

Step 1: Calculate room area

For rectangular rooms: Area = Length × Width

For L-shaped or irregular rooms: divide into rectangles, calculate each, and add together.

Step 2: Calculate area of one tile

Tile area = Tile length × Tile width

Use the same units as the room (inches or feet). If tiles are sold in inches, convert:

12 in × 12 in tile = 1 sq ft | 24 in × 24 in = 4 sq ft | 18 in × 18 in = 2.25 sq ft

Step 3: Divide room area by tile area

This gives the base tile count — before waste.

Step 4: Add the waste factor

Multiply the tile count by (1 + waste percentage) and always round up to a whole number.

Worked example

Room: 10 ft × 12 ft | Tile: 12 in × 12 in (1 sq ft each) | Straight layout, 10% waste

• Room area: 10 × 12 = 120 sq ft
• Tile area: 1 sq ft each
• Base count: 120 ÷ 1 = 120 tiles
• With 10% waste: 120 × 1.10 = 132 tiles
• Buy: 132 tiles (round up if this doesn't land on a whole number)

Second example: Non-square tile

Bathroom: 8 ft × 6 ft | Tile: 4 in × 8 in (ceramic subway) | Straight layout

• Room area: 48 sq ft = 6,912 sq in
• Tile area: 4 × 8 = 32 sq in
• Base count: 6,912 ÷ 32 = 216 tiles
• With 10% waste: 216 × 1.10 = 237.6 → 238 tiles

Waste Factor by Layout Pattern

Accounting for Obstacles

Kitchen islands, bathtubs, shower bases, and other fixed obstacles don't need tile. Subtract their area from the room area before calculating tiles:

Adjusted area = Room area − Obstacle area

Example: 10 × 12 ft bathroom with a 3 × 4 ft shower base:

• Room area: 120 sq ft
• Shower base area: 12 sq ft
• Tiling area: 108 sq ft → then add waste factor

Grout Lines and Their Effect

Grout lines (the gaps between tiles) reduce the effective tile coverage slightly but also affect the visual appearance of your floor or wall:

• 1/16 inch: Nearly seamless look, best with rectified (precisely sized) tiles
• 1/8 inch: Standard for floor tiles, balances appearance and practicality
• 1/4 inch: Recommended for handmade or irregular tiles with natural variation
• 1/2 inch: Used for rustic or large-format tiles where variation is expected

For practical tile quantity calculations, grout line width has a minimal effect on tile count — the waste factor already covers this. However, for budget calculations, larger grout lines mean more grout is needed.

Wall Tiles: Same Formula, Key Differences

Wall tile calculations use the same formula (area ÷ tile area + waste), but account for:

• Height of tiled area, not full floor area
• Subtracting areas not tiled (above countertops, around windows)
• Shower wall tiles often need 15% waste due to many corners and cuts
• Trim tiles (bullnose, pencil liner) are sold by the linear foot — calculate separately