Tile Calculator

Measuring Tips

• Measure length and width of the area in feet
• For multiple areas, calculate each separately and add totals
• Subtract areas not being tiled (fixtures, cabinets)
• For walls, measure height and width, subtract windows and doors
• Account for pattern waste: 10% straight, 15% diagonal, 20% herringbone

Tile Pattern Guide

Tips for Best Results

• Buy all tiles from the same dye lot for color consistency
• Keep extra tiles for future repairs
• Use spacers for consistent grout lines
• Seal grout after installation to prevent staining
• Plan layout before starting to minimize small cuts

Step 1: Calculate Net Area

Start by measuring the room and calculating the total area, then subtract any areas that will not be tiled:

Total Area = Room Length x Room Width

Net Area = Total Area - Exclusions

The calculator supports common bathroom exclusions such as bathtubs (approximately 14 sq ft), vanities (approximately 10 sq ft), and cabinets (approximately 15 sq ft). You can also enter a custom rectangular exclusion for items like kitchen islands or closet areas. For a 10 ft x 12 ft bathroom with a bathtub excluded: net area = 120 - 14 = 106 sq ft.

Step 2: Calculate Tiles Including Grout Lines

The calculator factors in the grout line width when determining how many tiles fit. Each tile occupies a unit area equal to the tile dimensions plus the grout line:

Tile Unit Area (sq in) = (Tile Length + Grout Line) x (Tile Width + Grout Line)

Base Tiles = (Net Area x 144) / Tile Unit Area

For example, 12x12 inch tiles with a 1/8 inch grout line on a 106 sq ft floor: tile unit area = (12.125 x 12.125) = 147.02 sq in. Net area in square inches = 106 x 144 = 15,264. Base tiles = 15,264 / 147.02 = 103.8 tiles.

Step 3: Apply Waste Factor and Round Up

The waste factor accounts for cuts at room edges, breakage during installation, and defects. The calculator applies the pattern-specific waste percentage:

Total Tiles = Ceiling(Base Tiles x (1 + Waste% / 100))

Continuing the example with 10% straight pattern waste: 103.8 x 1.10 = 114.18, rounded up to 115 tiles. If tiles come 10 per box, you would need 12 boxes (120 tiles). Always round up to full boxes when ordering.

Thinset Mortar

A standard 50-pound bag of modified thinset mortar covers approximately 50 square feet on floors (using a 1/4 x 3/8 inch square-notch trowel) and about 40 square feet on walls (where a slightly thinner application is typical). The calculator divides net area by the appropriate coverage rate:

Thinset Bags = Ceiling(Net Area / Coverage Rate)

For our 106 sq ft floor example: 106 / 50 = 2.12, so plan for 3 bags of thinset. Larger format tiles (over 16 inches on any side) require a deeper notch trowel (1/2 x 1/2 inch), which reduces coverage to about 35-40 sq ft per bag. Coverage values are informed by guidelines consistent with ANSI A118.4 for modified thinset mortar.

Grout

The calculator estimates grout at one 25-pound bag per 75 square feet, which is a conservative estimate that works well for most residential tile sizes with 1/8 to 3/16 inch grout joints. For our 106 sq ft example, you would need 2 bags. Grout coverage varies significantly based on tile size, joint width, and joint depth. Smaller tiles with wider joints consume much more grout than large-format tiles with narrow joints. Sanded grout is standard for joints 1/8 inch and wider, while unsanded grout is used for narrower joints. Epoxy grout, while more expensive, provides superior stain and chemical resistance and is an excellent choice for kitchens and high-traffic commercial floors.

• Forgetting to check the dye lot: Tiles from different production runs can have noticeable color variations. Always verify that all boxes share the same dye lot number, and order enough from a single lot to complete the project plus extras for repairs.
• Under-ordering for patterns: Diagonal and herringbone patterns generate significantly more waste than straight layouts because every perimeter tile requires angled cuts. A 10% waste factor that works for straight layout will leave you short for diagonal work.
• Not accounting for tile variation: Natural stone tiles vary in size and thickness from piece to piece. Order 15-20% extra for stone, even in straight patterns, to allow for culling defective pieces.
• Ignoring substrate preparation: Tile should be installed over a clean, flat, stable substrate. Floors with more than 1/4 inch of variation over 10 feet should be leveled with self-leveling compound before tiling. Budget for this additional material.
• Measuring only floor area for walls: When tiling shower walls, measure each wall individually and add them together. Do not forget the shower niche, which adds extra linear feet of perimeter cuts.

• Dry-lay before you install: Lay out tiles on the floor without mortar to visualize the pattern, identify awkward cuts, and adjust the starting line. This is especially important with large-format tiles and diagonal patterns.
• Back-butter large tiles: Tiles larger than 12x12 inches should be back-buttered in addition to troweling the floor. This ensures at least 95% mortar coverage, which is recommended for wet areas based on practices consistent with TCNA (Tile Council of North America) guidelines.
• Use a leveling system: Clip-and-wedge tile leveling systems prevent lippage (uneven tile edges) and are essential for large-format tile installations. They add cost but dramatically improve the finished appearance.
• Seal before grouting: Natural stone tiles should be sealed before grouting to prevent the grout from staining the stone surface. Use a penetrating sealer applied with a brush or roller and allow it to dry completely.
• Plan your starting point: Find the center of the room and snap chalk lines in both directions. Dry-lay tiles from center to each wall. If the perimeter cut at any wall is less than half a tile width, shift your starting line by half a tile width to avoid thin, fragile cuts.
• Invest in a quality wet saw: A good tile wet saw with a diamond blade makes clean cuts through porcelain and stone. For small jobs, most rental centers rent wet saws by the day for $40-$60.