Tile Calculator

The tile calculator answers the most common DIY question on any flooring or wall project: how many tiles do I need to finish this surface? Enter your room's length and width, the tile size from the manufacturer's spec sheet, the grout joint width you plan to use, and a waste percentage based on the layout.

The calculator computes total surface area (length × width for floors, perimeter × height for walls), the effective area each tile actually occupies including the grout joint, and the exact tile count plus a buffer for cuts, breakage and future repairs.

Use it for any rectangular surface:

• bathroom and kitchen floors
• shower walls
• kitchen backsplashes
• hallways
• mudrooms
• laundries
• balconies and patios

For L-shaped rooms or irregular layouts, divide the surface into rectangles, calculate each separately, and sum the tile counts.

Round up to whole boxes — tile is sold by the box across US, UK, CA and AU markets, and the spare tiles protect you against breakage during install and chips over the next 5-10 years.

• Step 1: Measure the surface. For floors, multiply room length by width in feet or meters. For walls, multiply perimeter (2 × length + 2 × width) by ceiling height; subtract doors (~21 sqft each) and windows (~15 sqft each).
• Step 2: Compute the effective tile area. Take the tile's length and width, add the grout joint width to each dimension, then multiply: (tile_L + grout) × (tile_W + grout). A 12 × 12 in tile with a 1/8 in grout joint occupies 12.125 × 12.125 = 147.0 sq in or 1.02 sqft.
• Step 3: Divide surface area by effective tile area to get the bare minimum tile count. A 120 sqft floor needs 120 ÷ 1.02 = 117.6 tiles.
• Step 4: Multiply by (1 + waste percent ÷ 100) and round up. For a 10% buffer: 117.6 × 1.10 = 129.4 → 130 tiles. Then round up to whole boxes: 130 tiles ÷ 10 per box = 13 boxes (132 tiles total).

The calculator above does every step automatically when you enter your inputs.

Tile coverage is the floor or wall area a single tile (or full box) actually covers when installed, including the grout joint. A 12 × 12 in tile alone is 1.00 sqft of tile, but in place with a 1/8 in joint it covers 1.02 sqft.

A box of 10 covers 10.2 sqft, not exactly 10 — small but meaningful when you're ordering 13 boxes for a bathroom floor. Manufacturers' boxes typically state 'covers X sqft' assuming a specific grout width; verify the assumption.

Common box coverage by tile size:

• 12 × 12 in = 8-12 sqft per box
• 12 × 24 in = 12-16 sqft
• 18 × 18 in = 11-15 sqft
• 24 × 24 in = 12-20 sqft
• 3 × 6 in subway = 7-10 sqft (60-80 tiles)
• 2 × 2 in mosaic on mesh = 10-12 sqft (11-12 sheets)

Switch the calculator to metric for sqm coverage: 1 sqft = 0.093 sqm and 1 sqm = 10.76 sqft for cross-checking with UK/AU manufacturer specifications.

Different room types have characteristic floor sizes and tile preferences.

• Bedrooms (10-14 ft × 12-16 ft) typically use 12 × 24 in or 24 × 24 in porcelain plank to make the room feel larger — about 60-150 tiles per room with 10% waste.
• Living rooms and great rooms (16-24 ft × 18-30 ft) suit large-format 24 × 24 in or 24 × 48 in tiles in 250-700 sqft layouts; account for 12-15% waste because of the larger cuts.
• Hallways (3-5 ft × 8-30 ft) often use plank tile laid lengthwise; the long-narrow geometry leaves little waste so 8-10% buffer is enough.
• Open-plan kitchens with adjoining dining rooms benefit from a single tile size carried across both zones for visual continuity — calculate the combined area (typically 300-600 sqft) and order in one shipment to guarantee dye-lot consistency.

Subtract built-in features (vanities, kitchen islands, fireplaces) from the floor area before calculating tile needed.

Bathrooms typically combine three tile zones — floor, shower walls, and decorative wainscot — each with different tile sizes and grout widths.

• A small 5 × 8 ft bathroom floor (40 sqft) needs 50 tiles in 12 × 12 in porcelain at 10% waste.
• A 60 × 32 in alcove shower with walls to 80 in height (51 sqft of wall area) needs 250-300 subway tiles at 15% waste because of corner cuts and the niche cutout.
• Wainscot at 36 in height around a small bathroom adds 30-40 sqft of wall tile.

Use 1/8 in grout joints on floors and 1/16 in joints on walls and backsplashes for a clean look. Always tile the shower walls before the floor so cut edges sit hidden under the bottom row. Add Schluter or bullnose trim for outside corners and edges — typically 5-10 trim pieces per bathroom.

Subtract the area under the vanity, toilet base and bathtub (typically 8-15 sqft total in a small bathroom) from your floor calculation.

Kitchens use tile in two main zones — floor and backsplash — each calculated separately.

Floors: a typical 10 × 14 ft kitchen has 140 sqft, but cabinets, the island and the refrigerator footprint usually subtract 25-40 sqft, leaving 100-115 sqft of usable tile area. Use 10-12% waste because of the cuts around toe-kicks and appliances.

Backsplash: measure length along the countertop edge × height to the upper cabinets (typically 18 in / 45 cm). A 12 ft countertop run yields 18 sqft of backsplash. Subtract any area behind appliances (range, microwave) you don't plan to tile.

Common backsplash tiles:

• 3 × 6 in subway (60-80 per 18 sqft)
• small mosaic sheets (3-5 sheets)
• 4 × 12 in plank tile

Use a tight 1/16 in grout joint for a clean modern look. Add 15% waste because of cuts around outlets, switches and cabinet corners. Trim the top and side edges with bullnose, Schluter, or pencil-trim tiles.

Grout joint width is both a calculation input and an aesthetic decision.

Common joints by application:

• backsplashes and feature walls = 1/16 in (1.5 mm), used for rectified porcelain and small subway tiles
• standard floor and wall = 1/8 in (3 mm), the universal residential default
• rustic or natural stone = 3/16 to 1/4 in (5-6 mm), needed when tile sizes vary slightly
• large-format outdoor patios = 1/4 to 3/8 in (6-10 mm), allows for thermal expansion

The width affects tile count slightly — wider joints reduce tiles needed by 1-4% — and grout volume significantly: 1/16 in joints use 4-6 lb of grout per 100 sqft, 1/8 in uses 8-10 lb, 1/4 in uses 15-20 lb.

The calculator uses joint width to compute effective tile area; standard sanded grout for joints 1/8 in and wider, unsanded for 1/16 in. TCNA in the US, BSI BS 5385 in the UK, TTMAC in Canada and AS 3958 in Australia all specify minimum joint widths by tile type and application — consult the relevant standard for compliance on professional projects.

Waste percentage is the buffer added to the calculated tile count to cover cuts, breakage during install, and a few spares for future repairs.

Standard guidance:

• 10% for straight layouts on rectangular rooms with simple geometry — the safest baseline that most installers default to.
• 12-13% for brick or running-bond layouts, where every other row is offset by half a tile and produces extra cut waste at the ends.
• 15% for diagonal layouts (rotated 45° from the walls), where every perimeter tile is cut at an angle leaving an unusable triangular offcut.
• 18-20% for L-shaped or curved rooms where cut waste compounds, and for large-format tiles where each cut wastes a larger absolute area.
• 20-25% for herringbone, chevron, hexagon mosaics or any pattern where tiles meet at angles producing many small offcuts.

Beyond the waste buffer, save 5-10 spare tiles in the original box for future repairs — manufacturers discontinue patterns within 2-3 years and color-matching from a fresh batch is rarely possible.

Tile body type affects price, durability and waste — but not coverage for a given size. A 12 × 12 in tile is 12 × 12 in regardless of whether it's ceramic, porcelain or marble.

• Ceramic: low-fired clay with a glazed face, water absorption 3-7%, suited to indoor walls and low-traffic floors, $1.50-3.00 per sqft. Use 10-12% waste because the body is softer and chips during cutting.
• Porcelain: high-fired dense clay, water absorption <0.5%, suited to high-traffic floors, showers, exteriors and frost-prone climates (UK, Canadian winters), $4-8 per sqft for residential grades. Use 8-10% waste because cuts are cleaner.
• Natural stone (marble, travertine, slate, limestone): variable density, requires sealing, $10-25+ per sqft. Use 12-15% waste because of natural color variation that requires manual sorting and rejection of mismatched tiles.

The calculator handles all three identically; just enter your tile dimensions and apply the appropriate waste percentage.

After calculating tiles needed, multiply by the price per tile (or per box) for total tile cost.

Typical 2026 pricing:

• budget ceramic floor tile = $1.50-3.00 per sqft (US/CA) / £1.50-3.00 per sqft (UK) / $3-6 per sqm (AU)
• mid-range porcelain = $4-8 per sqft / $9-18 per sqm
• premium natural stone = $10-25+ per sqft / $25-60+ per sqm

Premium designer brands (Bedrosians, Ann Sacks, Mandarin Stone, Beaumont Tiles) can cost $15-40 per sqft.

Beyond tile, budget for:

• thinset mortar ($25-50 per project, $30-80 per 50 lb bag depending on type)
• grout ($15-30 per 25 lb bag, 1-2 bags for typical bathroom)
• waterproofing membrane for wet areas ($40-80 for shower kit)
• edge trim or bullnose ($30-100)
• spacers and tools ($25-75 if you don't already own them)

Total materials cost typically runs 25-40% more than tile alone for a complete project — factor that in when budgeting.

Accurate measurement is the single biggest factor in calculator accuracy — measure twice, calculate once, order with a buffer. Use a tape measure or laser distance meter; lasers are far more accurate over distances above 8 ft.

Measure the longest length and the widest width of the room — not just one wall, because rooms are rarely perfectly rectangular. For L-shaped rooms, divide the floor into rectangles, measure each section separately, and sum the areas. For rooms with bay windows, alcoves, or sloped ceilings, measure each major surface independently.

Subtract built-in features that won't be tiled:

• vanities (~6-15 sqft)
• kitchen islands (~15-40 sqft)
• bathtubs (~13 sqft)
• fireplaces (~10-20 sqft)

Account for the toilet flange and threshold transitions in bathrooms — these reduce usable tile area by 1-2 sqft.

The most common pitfall: measuring only one wall length and assuming the opposite wall is identical. In old houses, walls can be off by 1-3 inches, causing entire rows to be cut at an angle. Always measure both opposing walls.

Professional installers use the same formula as the calculator above but with refinements that improve accuracy on bid-quality estimates.

• (1) Apply tile-size waste multipliers: 8-10% for 6-12 in tiles in straight layout; 10-12% for 18-24 in tiles; 12-15% for 24-48 in large-format planks; 15-20% for any pattern with cuts at angles (herringbone, hexagon, chevron).
• (2) Pattern multipliers: straight = 1.0×, brick offset = 1.05×, diagonal = 1.10×, herringbone = 1.20×, hexagon mosaic = 1.15×.
• (3) Substrate adjustments: smooth concrete = no change; OSB or plywood subfloor = +5% for cuts around fasteners; existing tile being overlaid = +3% for level corrections.
• (4) Trim allowance: 5-15 trim pieces per bathroom, 8-20 per kitchen, depending on edge complexity.
• (5) Spare tile policy: deliver 5-10 spare tiles per project and document the dye lot on the invoice — protects your reputation when the homeowner needs a repair 2-5 years later.

The calculator gives you the base number; apply your professional multipliers from there to produce client-ready bids.