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Tile Calculator

Tiling a floor or wall transforms a space, but the project can derail quickly if you run out of tiles mid-installation. Tile stores sell by the box, and boxes from different production batches can have subtle color variations. Running out means either living with mismatched tiles or delaying the project while you hunt for matching inventory. This tile calculator eliminates the guesswork by accounting for tile size, room dimensions, installation pattern, and waste factors to tell you exactly how many boxes to order. Different tile patterns waste different amounts of material. A straight grid pattern minimizes cuts and waste at around 10%. Diagonal patterns—where tiles are rotated 45 degrees—require more edge cuts and waste 15%. Herringbone patterns, with their intricate zigzag layout, waste up to 20% because nearly every tile needs precise angle cuts. This calculator adjusts for your chosen pattern so you order the right quantity the first time. Professional tile installers think in terms of coverage rates and waste factors, not just raw square footage. A 12×10 foot room is 120 square feet, but you'll need tiles to cover more than 120 square feet once you account for cuts around cabinets, doorways, and pattern waste. Our calculator does the math for you, converting room dimensions to tile count, box quantities, and even estimating the grout and thinset you'll need to complete the job.

100% Free
No Data Stored
Instant Results
ft
ft
Room Area
120.0
sq ft
Tile Area Each
1.000
sq ft
Waste Factor
10%
for straight pattern
Tiles Needed
133
tiles (with waste)
Boxes to Order
12
boxes (12 tiles/box)
Grout Bags
4
bags
Thinset/Mortar
3
bags (50 lb)
Estimated Material Cost
$528
(tiles: $420 + supplies: $108)

Tiles Needed by Pattern (showing waste differences)

Straight (10% waste)133
Diagonal (15% waste)139
Herringbone (20% waste)145

Pro Tip: Always buy at least one extra box beyond the calculation. Tiles can chip during cutting or installation, and having perfect color-matched replacements years later is nearly impossible. For your 120 sq ft room with straight pattern, order 13 boxes to be safe. Store extras in a dry place for future repairs.

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Understanding Tile Sizes and Coverage

Tile is sold by the box, not by the piece, and each box contains a specific number of tiles based on size:

  • 6" × 6" tiles: Approximately 40 tiles per box, covering 10 sq ft. Popular for bathrooms and backsplashes. Requires more grout lines and labor.
  • 12" × 12" tiles: Approximately 12 tiles per box, covering 12 sq ft. The most common floor tile size. Good balance of coverage and handling.
  • 18" × 18" tiles: Approximately 8 tiles per box, covering 18 sq ft. Large format tiles make small rooms look bigger. Heavier and harder to cut.
  • 24" × 24" tiles: Approximately 6 tiles per box, covering 24 sq ft. Modern look with minimal grout lines. Requires perfectly flat subfloor.
  • 12" × 24" tiles (plank): Approximately 10 tiles per box, covering 20 sq ft. Mimics hardwood planks. Trendy but requires careful layout.

Box quantities and coverage vary by manufacturer and tile thickness. Always verify the coverage per box on the product label before ordering. Manufacturers list coverage in square feet per box, which simplifies ordering once you know your total square footage plus waste.

Larger tiles cover more area per piece, reducing installation time and grout line cleaning. However, they're heavier, harder to cut, and require flatter surfaces. Smaller tiles are more forgiving on uneven surfaces and allow tighter radius curves (like shower floors) but require more labor and grout.

Pattern Choices and Their Waste Factors

The installation pattern dramatically affects how much tile you'll waste:

Straight/Grid Pattern (10% waste): Tiles align in rows and columns. Simplest to install, fastest, and least wasteful. Border cuts are straight lines. Best for DIY beginners. Works with any tile size. Clean, classic look. Most cost-effective pattern.

Diagonal Pattern (15% waste): Tiles rotated 45 degrees to walls. Makes small rooms appear larger by drawing the eye along the diagonal. Every edge requires a diagonal cut, increasing waste. Requires careful planning to center the pattern. More labor-intensive than straight pattern. Striking visual effect worth the extra material cost.

Herringbone Pattern (20% waste): Rectangular tiles (like 12"×24") laid in a V-shaped weaving pattern. Creates dynamic, high-end look. Requires precise 45-degree cuts on nearly every tile. Most labor-intensive pattern. Best left to experienced installers. Popular with plank tiles to mimic hardwood herringbone floors. Highest material waste but premium aesthetic.

Waste factors account for edge cuts, pattern alignment, mistakes, and future repairs. Straight patterns waste the least because full tiles fill most of the field, and only perimeter cuts waste material. Complex patterns require cuts throughout the installation, not just at edges.

Other patterns include brick/running bond (offset rows, 12% waste), basketweave (pairs of tiles creating woven look, 15% waste), and pinwheel (square tiles with small accent squares, 15% waste). Each pattern has a characteristic waste factor based on cut complexity.

Why Grout Lines Matter for Tile Count

Grout lines occupy space between tiles, affecting how many tiles fit in your room. Standard grout line width is 1/8" to 1/4" depending on tile regularity:

  • Rectified tiles: Machine-cut edges, perfectly square, allows 1/8" grout lines. Tighter lines mean modern, seamless look.
  • Non-rectified tiles: Slightly irregular edges from molding process, requires 1/4" or larger grout lines to hide irregularity.
  • Large format tiles (18"+): Typically rectified with 1/8" lines. Any variation is very noticeable at large scale.
  • Mosaic/small tiles (under 6"): Often use 1/8" lines. More grout lines mean more grout and more cleaning.

For a 12' × 10' room with 12"×12" tiles and 1/4" grout lines, you fit 143 tiles with grout spacing vs. 144 tiles with no spacing. The difference seems small for one room, but grout lines add up across large areas. Our calculator includes this adjustment when you enable grout line spacing.

Grout line width also affects aesthetics and maintenance. Tight 1/8" lines create a modern, monolithic look where grout nearly disappears. Wide 1/4" lines make a bold design statement and are easier to fill without voids. Darker grout with white tile emphasizes the grid. Matching grout color minimizes the grid.

Estimating Grout and Thinset Mortar

Tiles are only part of the material list. You'll also need:

Thinset Mortar: The adhesive that bonds tiles to the substrate. Sold in bags (25 lb, 50 lb). Coverage depends on trowel notch size:

  • 1/4" × 1/4" square notch: Covers 75-90 sq ft per 50 lb bag (for tiles up to 8")
  • 1/4" × 3/8" square notch: Covers 50-60 sq ft per 50 lb bag (for 12" tiles)
  • 1/2" × 1/2" square notch: Covers 40-50 sq ft per 50 lb bag (for tiles 18"+)

Larger tiles require larger trowel notches for proper coverage and support. Insufficient thinset causes hollow spots that crack under weight. Our calculator assumes 1/4"×3/8" trowel (45 sq ft per bag), suitable for most floor tiles.

Grout: Fills gaps between tiles. Two types:

  • Sanded grout: For grout lines 1/8" and wider. Contains sand for strength. Typical coverage is 25-50 sq ft per 10 lb bag depending on tile size and line width.
  • Unsanded grout: For lines under 1/8". Used on polished marble and glass tile to avoid scratching. Covers similar area but more expensive.

Smaller tiles have more grout lines per square foot, requiring more grout. A 6"×6" tile has four times as many grout lines as a 12"×12" tile in the same area. Our calculator adjusts grout bag estimates based on tile size: 6" tiles need one bag per 25 sq ft, 12" tiles per 35 sq ft, 18"+ tiles per 50 sq ft.

Buy pre-mixed grout for small jobs (under 50 sq ft) for convenience. For larger jobs, dry-mix grout is more cost-effective. Add a grout sealer (one bottle covers 200-500 sq ft) to protect grout from stains and moisture, especially in kitchens and bathrooms.

The One Extra Box Rule

Professional installers always order at least one extra box beyond the calculated need. Here's why this matters:

Tile batches vary in color: Ceramic and porcelain tiles are fired in kilns, and slight temperature variations cause color shifts between batches. The difference is subtle when comparing individual tiles but obvious when installed next to each other. If you need replacements months or years later, stores may not have your exact batch. The lot number on the box identifies the batch—buy all tiles from the same lot.

Installation breakage: Even experienced installers break tiles during cutting or handling. A tile cutter can crack tiles along unintended lines. Dropped tiles shatter. Complex cuts around plumbing or outlets often take two or three attempts to get right. Having spares on-site prevents work stoppages.

Future repairs: Someone drops a cast iron pan. A cabinet installer scratches a tile dragging heavy equipment. Water damage requires replacing a section. If you have matching tiles stored safely, repairs are easy. Without them, you're replacing the entire floor or living with mismatched tiles.

Unused tiles are returnable (usually): Most suppliers accept returns of unopened boxes within 30-90 days. Check the return policy before buying. Keep your receipt and boxes intact. Return extras after the job is done, or store them for future repairs.

For a calculated need of 8 boxes, order 9 or even 10 boxes. The cost of one extra box ($30-$80) is trivial compared to the cost of ripping out and replacing a floor because you can't find matching tiles. It's cheap insurance against expensive problems.

Frequently Asked Questions

How do I measure an irregularly shaped room?
Break the room into rectangular sections. Measure each section separately and add the square footages together. For example, an L-shaped room becomes two rectangles. For curved areas or very complex shapes, use the largest rectangle that would contain the space and add 20% waste factor to account for the extra cuts. Alternatively, use graph paper to sketch the room to scale and count the tiles needed visually.
Should I include the area under cabinets when calculating tiles?
For kitchen and bathroom renovations where cabinets are already installed, do NOT tile under them—measure to the cabinet edges. For new construction or full remodels where cabinets install after flooring, you can choose: tiling under cabinets adds stability and allows future kitchen changes without exposed subfloor, but costs more in materials. Most installers tile to the cabinet front edge, saving 15-25% of floor area. Always tile under movable islands.
What is the best tile size for a small bathroom?
Contrary to intuition, larger tiles (12"×24" or even 18"×18") make small bathrooms appear bigger by reducing grout line clutter. Fewer grout lines create visual continuity. Avoid tiny mosaic tiles in small spaces—they make rooms feel busy and cramped. For very small bathrooms (under 40 sq ft), 12"×12" tiles offer a good compromise between modern look and ease of installation. Light-colored tiles in any size make spaces feel larger.
Can I tile over existing tile?
Yes, but with conditions. The existing tile must be firmly bonded, clean, and level. Loose or hollow-sounding tiles must be removed. Lightly sand glossy tile to improve thinset adhesion. Apply a bonding primer designed for tile-to-tile applications. The new tile raises the floor height by 1/2"-3/4", which affects door clearances, transitions, and appliances. If more than 10% of existing tiles are loose, full removal is better. For wet areas (showers, bathroom floors), removal is recommended to inspect waterproofing.
How much extra tile should I buy for future repairs?
Keep at least 5-10 extra tiles (about 1/2 to 1 full box) in storage after installation. Store tiles in a dry, climate-controlled space—garages and attics with extreme temperature swings can cause tile degradation. Wrap tiles in bubble wrap and label the box with the tile name, lot number, and purchase date. If you bought from a large chain store, note the SKU or product code for easier reordering if needed. Ten years from now, having two matching tiles can save you from a $5,000 floor replacement.
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Estimate Disclaimer

All calculations are estimates only. Actual material requirements may vary based on job site conditions, waste factors, and installation methods. Always verify quantities with a qualified contractor before purchasing materials. We are not responsible for over or under-ordering based on these estimates.