Tile Calculator
Calculate how many tiles you need for a floor or wall. Accounts for tile size, grout spacing, and waste percentage. Estimate how many tiles you need for a floor or wall project including waste factor. Calculate total cost based on tile price per unit.
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Fill in the fields and press Calculate to see instant results.
Tile Calculator – Calculate Tiles Needed for Floors & Walls
The Tile Calculator computes the exact number of tiles required for your flooring, shower wall, or kitchen backsplash project. By entering the dimensions of your room and the size of your chosen tile, the calculator determines total square footage, the total number of individual tiles needed, and the number of boxes you should order.
Running out of tile in the middle of a job is a disaster. Tiles are manufactured in specific "dye lots" (color batches). If you order a second batch later, the new tiles might be a slightly different shade of white or grey than your original tiles. Accurate estimation upfront ensures you get all your tiles from the same dye lot.
💡 The Waste Margin Rule: You must always order more tile than the exact mathematical area of your room. Tiles at the edges must be cut, and the cut-off pieces are often unusable. Standard grid layouts require a 10% waste margin. Diagonal layouts, herringbone patterns, or rooms with many cabinets require a 15% waste margin.
When to Use the Tile Calculator
🛁 Bathroom Renovations
Calculate tile for floors, shower walls, and niches. Bathrooms often require multiple tile sizes (e.g., 12x24 for walls, penny tile for the shower pan). Calculate each area separately.
🍳 Kitchen Backsplashes
Calculate subway tile or mosaics for the space between countertops and upper cabinets. This area involves many cuts for electrical outlets, requiring a 15% waste margin.
🏠 Main Floor Tiling
Calculate large-format tiles (like 24x24 or wood-look planks) for living rooms and hallways. These larger tiles often require higher waste margins because single cuts waste more material.
🧱 Outdoor Patios
Estimate porcelain pavers or natural stone tiles for outdoor living spaces. Outdoor tiles are often laid with wider grout lines, but standard calculations still apply.
💸 Budget Estimation
Convert the number of required boxes into a total material cost based on the price per square foot or price per box at the hardware store.
📏 Material Ordering
Ensure you buy enough boxes from the same pallet to guarantee matching dye lots, while leaving 1-2 boxes of spare tiles in the attic for future repairs.
Tile Calculation Formulas
The calculation requires converting both the room area and the tile area to the same unit (usually square inches), dividing them, and adding the waste margin.
Formula 1: Exact Number of Tiles
Formula 2: Total Tiles to Order
Common Tile Sizes & Coverage
| Tile Size (Inches) | Area per Tile | Tiles per 100 Sq Ft (w/ 10% Waste) |
|---|---|---|
| 12 × 12 | 1.0 sq ft | 110 tiles |
| 12 × 24 | 2.0 sq ft | 55 tiles |
| 24 × 24 | 4.0 sq ft | 28 tiles |
| 6 × 24 (Wood Plank) | 1.0 sq ft | 110 tiles |
| 3 × 6 (Subway Tile) | 0.125 sq ft | 880 tiles |
Step-by-Step Calculation Guide
Measure the Room
Measure the length and width of the floor or wall. For complex rooms (like L-shapes), break the room down into smaller rectangles, calculate each separately, and sum the areas.
Deduct Large Obstacles (Optional)
If there is a kitchen island or a bathtub, measure its footprint and subtract that area from the total. Do not bother subtracting small items like toilet footprints or floor vents — let the waste margin absorb them.
Enter Tile Dimensions
Input the length and width of your chosen tile in inches. Note: 'Nominal' sizes (like a 12x12 tile) might actually be 11.75 x 11.75 to account for grout, but using the 12x12 nominal size works perfectly for calculation.
Select the Waste Margin
Use 10% for standard grid layouts in simple square rooms. Use 15% for diagonal (diamond) layouts, herringbone patterns, hexagon tiles, or rooms with many angled walls and cabinets.
Calculate Boxes Needed
Most tile is sold by the box, not individually. Divide the total tiles required by the number of tiles per box, and always round UP to the nearest whole box.
Worked Examples
Given:
- • Room Dimensions: 8 ft × 10 ft
- • Tile Size: 12" × 12"
- • Waste Margin: 10%
Solution:
Room area: 8 × 10 = 80 square feet
Tile area: 12 × 12 = 144 sq in (1 sq ft)
Exact tiles: 80 ÷ 1 = 80 tiles
With 10% waste: 80 × 1.10 = 88 tiles
Result: You need 88 tiles. If they come 10 to a box, you need 9 boxes.
Given:
- • Wall Area: 15 ft wide × 1.5 ft high (18 inches)
- • Tile Size: 3" × 6" (Subway)
- • Waste Margin: 15% (due to outlets)
Solution:
Wall area: 15 × 1.5 = 22.5 square feet
Tile area: 3 × 6 = 18 sq in = 0.125 sq ft
Exact tiles: 22.5 ÷ 0.125 = 180 tiles
With 15% waste: 180 × 1.15 = 207 tiles
Result: You need 207 subway tiles. Backsplashes require higher waste margins because of the intricate cuts around cabinets and electrical outlets.
Given:
- • Room Dimensions: 20 ft × 15 ft
- • Tile Size: 12" × 24"
- • Waste Margin: 10%
Solution:
Room area: 20 × 15 = 300 square feet
Tile area: 12 × 24 = 288 sq in (2 sq ft)
Exact tiles: 300 ÷ 2 = 150 tiles
With 10% waste: 150 × 1.10 = 165 tiles
Result: You need 165 large-format tiles. Since 12x24 tiles cover 2 sq ft each, they cover large areas quickly.
Given:
- • Room Dimensions: 12 ft × 12 ft
- • Tile Size: 18" × 18"
- • Waste Margin: 15% (Diagonal)
Solution:
Room area: 144 square feet
Tile area: 18 × 18 = 324 sq in = 2.25 sq ft
Exact tiles: 144 ÷ 2.25 = 64 tiles
With 15% waste: 64 × 1.15 = 73.6 (Round up to 74 tiles)
Laying tiles on a 45-degree angle (diagonal) creates triangles at every wall edge. This wastes significantly more material than a straight grid layout.
Given:
- • Room Dimensions: 16 ft × 12 ft
- • Tile Size: 6" × 36"
- • Waste Margin: 10%
Solution:
Room area: 192 square feet
Tile area: 6 × 36 = 216 sq in = 1.5 sq ft
Exact tiles: 192 ÷ 1.5 = 128 tiles
With 10% waste: 128 × 1.10 = 140.8 (Round up to 141 tiles)
Wood-look planks are often laid in a staggered 'brick' pattern. A standard 10% waste margin is usually sufficient unless the room has many angles.
Common Mistakes to Avoid
Ordering the exact square footage without waste
The mathematical area is impossible to achieve in reality. You will have to cut tiles to fit the perimeter, and those off-cuts are usually thrown away. Not ordering waste guarantees you will run out of tile.
Buying from multiple dye lots
Tiles are baked in kilns, and color varies slightly between batches (dye lots). If you run out and go back to the store a week later, the new box might not match the ones you already installed.
Not saving 'attic stock'
Always keep 1-2 boxes of spare tile when the job is done. If you ever need to repair a cracked tile or run new plumbing through the floor, you will have exact matches.
Manually calculating grout lines
Trying to deduct the 1/8-inch grout lines from your calculation is tedious and usually results in under-ordering. Let the grout lines be absorbed by your waste margin calculation.
Ignoring large format tile waste
A 24x24 tile that requires a 2-inch strip cut off the side wastes a massive piece of material. Large format tiles in small rooms often require higher waste margins (15%) than small tiles.
Tips and Best Practices
- ✓Use the 15% rule for diagonals and herringbones. Patterns like herringbone or diagonal grids require cutting triangles at every single wall edge. This generates massive amounts of unusable off-cuts.
- ✓Check the box coverage closely. Tile boxes often list the 'Coverage Area' (e.g., 10.5 sq ft per box). You can divide your total room area (including waste margin) by this box coverage number to get the exact number of boxes.
- ✓Mix tiles from different boxes during installation. Even within the same dye lot, there are slight variations. Installers 'shuffle' tiles by pulling from 3 or 4 different boxes simultaneously to blend variations evenly.
- ✓Account for pattern repeats. Wood-look planks and faux-marble often have a repeating pattern (e.g., 6 unique faces). Ordering slightly more tile allows you to avoid putting two identical faces right next to each other.
- ✓Measure cabinets, not just the floor. In kitchens, base cabinets take up a lot of floor space. Don't pay for tile to go under cabinets if you don't intend to tile under them (though tiling wall-to-wall is considered best practice).
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Conclusion
The Tile Calculator takes the stress out of buying flooring materials. The golden rule of tile installation is simple: always buy all the tile you need (plus waste) at the exact same time to ensure it all comes from the same manufacturing dye lot.
By carefully measuring your room, calculating the square footage, and applying the correct waste margin (10% for straight grids, 15% for diagonal patterns or backsplashes), you guarantee you will have enough material to finish the job beautifully — with a few spare pieces left over for future repairs.
Note on Returns: Most big-box hardware stores allow you to return unopened boxes of tile. It is always better to over-order by one box and return it than to under-order and risk a mismatched dye lot later.
Frequently Asked Questions
How do you calculate how many tiles you need?
Calculate total room square footage. Divide by the square footage of a single tile. Add a 10% waste margin.
How much extra tile should I buy for waste?
Standard rule: 10% for straight grid patterns in square rooms. Use 15% for diagonal patterns, herringbone, or rooms with many angled walls.
How many 12x12 tiles do I need for 100 square feet?
A 12x12 tile is 1 square foot. You need 100 tiles, plus 10% waste = 110 tiles total.
How many 12x24 tiles do I need for 100 square feet?
A 12x24 tile is 2 square feet. You need 50 tiles (100 ÷ 2), plus 10% waste = 55 tiles total.
Do I need to account for grout lines?
No. For standard tile sizes and standard grout widths (1/8"), the grout space is negligible and is absorbed by the waste margin calculation.
Should I buy extra tile for future repairs?
Yes. Keep 1-2 boxes of 'attic stock'. Tiles crack over time, and finding the exact dye lot 5 years later is nearly impossible.
How do I calculate for a backsplash?
Measure width × height in inches, divide by 144 to get square feet. Use a 15% waste margin due to the high number of cuts around outlets.
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