Calculate how many tiles you need for a floor, wall or backsplash — with grout joint allowance, waste factor, cost estimate and box quantities.
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Enter room dimensions, tile size, grout joint width and waste factor — optionally add a tile price for cost totals.
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Calculate the room area in square feet (length × width). Calculate the tile area in square feet (tile L in inches × tile W in inches) ÷ 144. Divide room area by tile area to get number of tiles. Add a waste factor of 10–15% for straight lay, 15–20% for diagonal. For a 120 sq ft room with 12×12 tiles: tile area = 1 sq ft each; tiles needed = 120 × 1.15 = 138 tiles.
Straight lay pattern: add 10% waste. Diagonal (45°) lay: add 15% waste (more cuts at perimeter). Brick/offset pattern: add 10–12% waste. Complex patterns (herringbone, hexagon): add 15–20%. Small rooms with many cut edges relative to total area: add 20%. It is better to over-order slightly — dye lots differ between production runs, making exact colour matching impossible later.
Large format tiles (24×24 or 18×18 inches) make small rooms appear larger but require a very flat subfloor and more skill to install. Standard 12×12 and 12×24 tiles are versatile and forgiving. Small tiles (mosaic, penny, 4×4) require more grout joints (maintenance) but are flexible on curved surfaces. For bathrooms: 6×6 to 12×12 is common; for living areas: 12×24 or larger is on trend.
Rectified tiles (precision cut, consistent size): 1/16 to 1/8 inch joints. Non-rectified tiles (slightly variable size): 3/16 to 1/4 inch joints. Floor tiles generally: 1/8 to 3/16 inch. Large format floor tiles: 1/8 to 1/4 inch. Mosaic tiles on mesh: as specified (usually 1/16 to 1/8 inch). Wider joints are more forgiving of minor lippage (tile height differences) but collect more dirt.
Floor tile has a PEI (Porcelain Enamel Institute) hardness rating and must withstand foot traffic and abrasion. Wall tile does not need this hardness and is often lighter and thinner. Floor tile can generally be used on walls, but many wall tiles are not rated for floor use. For wet areas (showers), tiles must also have a low water absorption rating (≤0.5% for porcelain). Always check ratings before purchasing.
DIY tile installation costs: tile ($1–$15 per sq ft), adhesive/thin-set ($0.50–$1/sq ft), grout ($0.30–$0.75/sq ft), tools ($50–$200 one-time). Professional installation adds $5–$15 per sq ft in labour. Total cost: $7–$30 per sq ft installed professionally. Complex patterns, difficult surfaces, and heated floor systems increase cost. Bathroom floors are typically $400–$1,500 installed; kitchen floors $500–$3,000.
Find the centre of the room and plan layout from there to ensure cut tiles at the perimeter are equal on opposite walls. Avoid cuts under 1/2 tile width — adjust the starting point if needed. For a bathroom, centre the layout on the most visible wall. In kitchens, centre on the most visible area. Dry-lay tiles without adhesive first to visualise the pattern and confirm cuts.
Yes, with conditions: the existing tile must be firmly bonded (no hollow spots), the surface must be flat (no lippage over 1/8 inch), the added height must be acceptable (typically 1/4 to 1/2 inch extra per tile layer), and door clearances, thresholds and transitions must be checked. Tiling over existing tile saves the messy demolition but adds weight — check subfloor load capacity for multiple layers.
Both are clay-based, fired tiles. Porcelain is denser (water absorption <0.5%), harder (PEI 4–5), more durable and frost-resistant — suitable for outdoors and heavy-traffic floors. Ceramic is more porous (water absorption 1–6%), softer, easier to cut, and usually less expensive — better for walls and light-traffic indoor floors. Full-body porcelain has colour through the tile; glazed ceramic has colour only on the surface.
Measure the backsplash area in square feet (typically height × width of each section between cabinets and upper cabinets). Subtract areas with windows or appliances. Add 10–15% waste. For a standard kitchen backsplash: width of countertop (say 10 ft) × height (18 inches = 1.5 ft) = 15 sq ft, minus a window (3 sq ft) = 12 sq ft + 15% = 13.8 sq ft. Order at least 14 sq ft of tile.
