Tile Calculator: Floor Planning Made Simple for DIY Projects

Tile installation is expensive—materials alone can cost $3-15 per square foot. Ordering too few tiles means delays, color matching issues, and extra delivery fees. Ordering too many wastes hundreds of dollars. A tile calculator ensures you order exactly what you need (plus appropriate waste factor).

Basic Tile Calculation Formula

For Square/Rectangular Rooms: Room Length × Room Width = Square Footage Square Footage × 1.10 (10% waste factor) = Total Square Footage Needed Total Square Footage ÷ Tile Coverage Area = Number of Tiles

Example: 10' × 12' bathroom = 120 sq ft 120 × 1.10 = 132 sq ft (with waste) Using 12" × 12" tiles (1 sq ft per tile): 132 tiles needed

Tile Size and Coverage

Common tile sizes and coverage per tile:

Small Format:

• 4" × 4" tile = 0.11 sq ft per tile
• 6" × 6" tile = 0.25 sq ft per tile

Medium Format:

• 12" × 12" tile = 1 sq ft per tile
• 12" × 24" tile = 2 sq ft per tile

Large Format:

• 18" × 18" tile = 2.25 sq ft per tile
• 24" × 24" tile = 4 sq ft per tile
• 24" × 48" tile = 8 sq ft per tile

Larger tiles mean fewer grout lines but require flatter floors. They're also more expensive per tile but cover more area.

Waste Factor: How Much Extra to Buy

The 10% waste rule is oversimplified. Actual waste depends on:

Simple Layouts (5-7% waste):

• Straight lay pattern
• Minimal cuts
• Rectangular rooms
• No pattern matching

Standard Layouts (10-15% waste):

• Some cuts around fixtures
• Standard diagonal pattern
• Typical residential rooms
• Minor pattern matching

Complex Layouts (15-20% waste):

• Diagonal or herringbone pattern
• Many cuts and angles
• Irregular room shapes
• Intricate pattern matching

Very Complex (20-25% waste):

• Mosaic patterns
• Multiple tile sizes
• Curved walls
• Extensive custom cuts

Example: 120 sq ft bathroom, 12"×12" tiles, herringbone pattern 120 × 1.20 = 144 sq ft needed 144 tiles required (vs. 132 for straight lay)

That's 12 extra tiles for the complex pattern.

Calculating for Different Room Shapes

L-Shaped Rooms: Break into rectangles:

• Section A: 10' × 12' = 120 sq ft
• Section B: 6' × 8' = 48 sq ft
• Total: 168 sq ft

Rooms with Angles: Break into triangles and rectangles. For triangles: Triangle Area = (Base × Height) ÷ 2

Circular or Curved Areas: Use online calculators for complex curves, or approximate with grid method (count full squares + estimate partial squares).

Tile Patterns and Their Impact

Straight Lay (Grid Pattern):

• Simplest installation
• Least waste (5-7%)
• Fastest installation
• Best for beginners

Diagonal (Diamond Pattern):

• More visual interest
• 10-15% waste
• Makes small rooms look larger
• More cuts at edges

Brick/Running Bond (Offset Pattern):

• Classic look, especially for rectangular tiles
• 10-12% waste
• Common for subway tiles
• Moderate difficulty

Herringbone:

• Elegant, high-end look
• 15-20% waste
• Time-intensive installation
• Requires precision cutting

Chevron:

• Similar to herringbone but tiles are cut at angles
• 20-25% waste
• Most complex pattern
• Professional installation recommended

Calculating Tiles for Walls and Backsplashes

Kitchen Backsplash: Measure width and height of area between countertop and cabinets:

Example:

• 10 linear feet of countertop
• 18" height backsplash
• 10' × 1.5' = 15 sq ft
• Using 3"×6" subway tiles = 0.125 sq ft per tile
• 15 ÷ 0.125 = 120 tiles
• Add 10% waste: 132 tiles needed

Shower Walls: Calculate each wall separately:

Example shower:

• Back wall: 4' × 8' = 32 sq ft
• Left wall: 3' × 8' = 24 sq ft
• Right wall: 3' × 8' = 24 sq ft
• Total: 80 sq ft
• Add 15% waste (shower niche cuts): 92 sq ft

Budget and Cost Calculations

Total Project Cost Components:

1. Tile Cost: Square footage needed × price per sq ft

Example: 132 sq ft × $4.50/sq ft = $594

2. Grout: $15-30 per bag, covers 100-200 sq ft depending on grout line width 132 sq ft with standard grout lines = 1 bag = $20

3. Thinset/Mortar: $20-40 per bag, covers 80-120 sq ft 132 sq ft = 2 bags = $60

4. Underlayment (if needed): $1-2 per sq ft 132 sq ft = $132-264

5. Tile Spacers: $5-10 per bag

6. Tools (if DIYing):

• Tile cutter: $50-150
• Wet saw rental: $60-100 per day
• Trowel, sponges, buckets: $50

Total Example Project Cost: $594 (tile) + $20 (grout) + $60 (mortar) + $180 (underlayment) + $10 (spacers) + $100 (tools) = $964

Versus professional installation at $8-15 per sq ft: 132 sq ft × $12/sq ft = $1,584 (labor + materials)

DIY saves about $600 on this project.

Real Project Examples

Example 1: Small Bathroom Floor

• 5' × 8' room = 40 sq ft
• Using 12" × 12" porcelain tiles
• Straight lay pattern
• 40 × 1.07 (7% waste) = 42.8 sq ft
• 43 tiles needed
• Tile cost at $3.50/sq ft: $150
• Grout + mortar: $35
• Total materials: $185

Example 2: Kitchen Floor

• 12' × 15' room = 180 sq ft
• Minus island: 4' × 6' = 24 sq ft
• Net area: 156 sq ft
• Using 18" × 18" tiles
• Diagonal pattern
• 156 × 1.15 (15% waste) = 179.4 sq ft
• 179.4 ÷ 2.25 = 80 tiles needed
• Tile cost at $6/sq ft: $1,074
• Underlayment, grout, mortar: $220
• Total materials: $1,294

Example 3: Shower Surround

• Three walls: 80 sq ft calculated above
• Using 6" × 6" tiles
• Standard pattern with decorative accent
• 80 × 1.15 = 92 sq ft needed
• 92 ÷ 0.25 = 368 tiles
• Tile cost at $8/sq ft: $736
• Waterproofing membrane: $100
• Grout, mortar, supplies: $120
• Total materials: $956

Tile Quality and Durability Ratings

PEI Rating (Durability for Foot Traffic):

• PEI 1: Wall tile only (not for floors)
• PEI 2: Light traffic (bathroom floors)
• PEI 3: Medium traffic (all residential)
• PEI 4: Heavy traffic (commercial/entry ways)
• PEI 5: Extra heavy (commercial)

For residential floors, PEI 3 is minimum. Kitchens and entryways should use PEI 4.

Water Absorption (for wet areas):

• Impervious (<0.5%): Best for showers, pools
• Vitreous (0.5-3%): Good for bathrooms
• Semi-vitreous (3-7%): Indoor use only
• Non-vitreous (>7%): Dry areas only

Always use impervious tiles for shower floors and walls.

Common Tile Calculation Mistakes

Mistake #1: Not Ordering Extra for Future Repairs Tile dye lots vary. Order 5-10% extra and store it for future repairs. Trying to match discontinued tile in 5 years is nearly impossible.

Mistake #2: Forgetting About Grout Line Width Wider grout lines mean more tiles needed. The calculator's square footage accounts for this, but it's why you can't simply divide room square footage by tile square footage exactly.

Mistake #3: Not Considering Tile Direction Running 12"×24" tiles lengthwise vs. widthwise in a room affects how many need cutting and waste factor.

Mistake #4: Ignoring Floor Levelness Uneven floors require more thinset and potentially more tile breakage. Factor in 5% extra waste if floor isn't level.

Mistake #5: Not Accounting for Thresholds and Transitions Doorways need transition strips or bullnose tiles. Add these separately to your tile count.

Frequently Asked Questions

How many tiles do I need for a 10×10 room? For a 100 sq ft room with 12"×12" tiles: 100 × 1.10 = 110 tiles needed (includes 10% waste factor for straight lay pattern).

Should I buy extra tiles for future repairs? Yes, buy 5-10% extra beyond waste factor. Tile dye lots change, and finding exact matches years later is difficult. Store extras in a dry, safe place.

How do I calculate tiles for diagonal layout? Use same square footage calculation but increase waste factor to 15% instead of 10%. Diagonal cuts at edges create more waste than straight layouts.

What size tile is best for small bathrooms? 12"×12" or 12"×24" tiles make small bathrooms look larger. Avoid tiles smaller than 6"×6" as excessive grout lines make spaces look busy and smaller.

How much does tile installation cost? Professional installation ranges $8-15 per square foot depending on tile size, pattern complexity, and location. DIY saves 50-70% but requires tools and time.

Plan your tile project with our Tile Calculator for accurate material estimates. Also check our Paint Calculator for walls and our Carpet Calculator for alternative flooring options.