Estimate tile quantity, box count, waste, and material cost for floors and walls using US and UK units.
This tile calculator gives a planning estimate only. Tile sizing, grout lines, pattern, cuts, breakage, trim pieces, and manufacturer pack coverage can all affect final quantities. Always round up and confirm with your supplier before ordering.
freeusukcalculator.com
| Item | Value |
|---|
Tiling a floor, bathroom, or kitchen is one of the most rewarding home improvement projects β but getting the quantities wrong means either running out of tiles mid-job or over-ordering hundreds of pounds worth of material. This guide walks through exactly how to calculate tiles needed for any room, explains the key differences between US and UK tile sizes and standards, covers every pattern type from simple grid to complex herringbone, and helps you estimate adhesive, grout, and total project cost before you spend a penny.
The core formula for calculating how many tiles you need is straightforward:
Formula: Number of tiles = (Room area Γ· Tile area) Γ (1 + waste factor)
Example (US): A 12 ft Γ 10 ft bathroom floor = 120 sq ft. Using 12" Γ 12" tiles (1 sq ft each): 120 Γ· 1 = 120 tiles. With 10% waste: 120 Γ 1.10 = 132 tiles needed.
Example (UK): A 3.5 m Γ 2.8 m kitchen floor = 9.8 mΒ². Using 600 mm Γ 600 mm tiles (0.36 mΒ² each): 9.8 Γ· 0.36 = 27.2 tiles. With 10% waste: 27.2 Γ 1.10 = 30 tiles needed (round up to 30 or order 33 for a full pack).
| US Size (inches) | UK/Metric Size (mm) | Tile Area (sq ft) | Tile Area (mΒ²) | Common Use |
|---|---|---|---|---|
| 4" Γ 4" | 100 Γ 100 | 0.11 | 0.01 | Bathroom walls, splashbacks |
| 6" Γ 6" | 150 Γ 150 | 0.25 | 0.0225 | Bathroom floors, small spaces |
| 12" Γ 12" | 300 Γ 300 | 1.00 | 0.09 | Floors, general use |
| 12" Γ 24" | 300 Γ 600 | 2.00 | 0.18 | Bathroom walls, modern kitchens |
| 18" Γ 18" | 450 Γ 450 | 2.25 | 0.2025 | Large floors, hallways |
| 24" Γ 24" | 600 Γ 600 | 4.00 | 0.36 | Open-plan floors, commercial |
| β | 600 Γ 1200 | β | 0.72 | Contemporary large-format UK floors |
Always order more tiles than your exact calculation. You need extra for:
| Layout Pattern | Recommended Waste % | Reason |
|---|---|---|
| Straight grid (aligned joints) | 10% | Minimal cuts, easiest to plan |
| Brick bond / offset (50% offset) | 10β15% | End cuts on every other row |
| Diagonal (45Β°) | 15β20% | Triangle cuts on all four walls |
| Herringbone | 15β20% | Angled cuts at edges, complex layout |
| Pinwheel / basket weave | 10β15% | Mixed sizes, moderate edge waste |
The simplest pattern: tiles align horizontally and vertically with continuous grout lines running the full length and width. Best for large-format tiles and rooms where you want a clean, modern look. Easiest for DIY installation. Most popular in the US for 12"Γ12" and 18"Γ18" floor tiles.
Each row is offset by half a tile length, like brickwork. This is the most popular pattern in the UK for 300Γ600mm wall tiles in bathrooms and is also very common in the US for subway tiles (3"Γ6" or 75Γ150mm). The offset creates a pleasing rhythm and helps disguise slightly uneven wall surfaces.
Square tiles are rotated 45 degrees and laid at an angle to the walls. This makes a room feel larger and more dynamic, but increases waste by 15β20% because you need triangular cuts along every wall. Common for entrance halls in both the US and UK. Works best with square tiles of equal dimensions.
Rectangular tiles are laid at 45 or 90 degrees in a V-pattern. Popular for kitchen splashbacks and bathroom floors in both countries. Herringbone using 75Γ150mm metro/subway tiles is extremely fashionable in UK bathrooms and US kitchen backsplashes. Requires careful planning and adds 15β20% to tile quantity.
Grout joints β the gaps between tiles β consume space. Typical grout joint widths:
Grout joints slightly reduce the effective coverage of each tile. For a 600Γ600mm tile with a 3mm joint, the effective grid is 603Γ603mm. This is usually negligible for calculation purposes but becomes significant when planning exact tile counts for narrow strips.
The amount of grout needed depends on tile size, joint width, and tile thickness. A simplified formula for estimating grout in kilograms:
Grout (kg) = (Tile perimeter in mm Γ Joint width in mm Γ Tile thickness in mm Γ Area in mΒ²) Γ· (Tile length Γ Tile width Γ Grout density)
For a typical 300Γ600mm floor tile with 3mm joints, 9mm thickness, over 10 mΒ²: approximately 1.5β2 kg of grout powder. As a practical rule of thumb:
Tile adhesive coverage varies by brand and tile size. General guidelines:
In the UK, adhesive is typically sold in 20 kg bags. In the US, thinset mortar is sold in 50 lb bags. One 20 kg bag covers approximately 5β8 mΒ² depending on the application method. One 50 lb bag of US thinset covers roughly 40β60 sq ft.
Bathroom wall tiles must be waterproof or applied over a waterproof membrane. In the US, cement board (Hardiebacker or Durock) is the standard substrate behind tiles in wet areas. In the UK, tile backer boards (Wedi, Aquapanel) are preferred. Tiles above shower trays and baths need a flexible grout (containing acrylic) to accommodate movement, and silicone sealant rather than grout in internal corners.
Splashbacks are typically 150β600mm high behind a kitchen worktop. Metro/subway tiles (75Γ150mm or 3"Γ6") are by far the most popular choice in both the US and UK. They are easy to clean, available in countless colors, and suit both traditional and contemporary kitchens. Measure the linear metres (UK) or linear feet (US) of splashback and multiply by height to get the area.
Floor tiles must have a slip resistance rating appropriate for the location. In the US, the DCOF (Dynamic Coefficient of Friction) standard requires β₯0.42 for floors used in wet barefoot areas. In the UK, the R-rating system (R9 to R13) is used; R10 is recommended for domestic bathrooms and kitchens, R11 for commercial kitchens. Floor tiles must also be rated for the expected foot traffic level.
Tile costs vary enormously by material and size. Approximate ranges:
| Tile Type | US Price (per sq ft) | UK Price (per mΒ²) |
|---|---|---|
| Basic ceramic floor tile | $0.50β$3 | Β£5βΒ£20 |
| Porcelain floor tile | $2β$8 | Β£15βΒ£50 |
| Natural stone (travertine, slate) | $5β$20 | Β£30βΒ£120 |
| Large-format porcelain (600Γ1200mm) | $8β$20 | Β£30βΒ£80 |
| Metro/subway wall tile | $2β$6 | Β£10βΒ£35 |
| Handmade/artisan tile | $10β$50+ | Β£50βΒ£200+ |
Each 600Γ600mm tile has an area of 0.36 mΒ². Divide 20 by 0.36 = 55.6 tiles. Add 10% waste: 55.6 Γ 1.10 = 61.2. Round up to 62 tiles minimum, but since tiles are sold in packs (typically 3β5 tiles per pack covering 1.08β1.80 mΒ²), buy enough full packs to cover at least 62 tiles plus keep a few spare.
Each 12Γ12" tile covers 1 sq ft. You need 150 tiles for the base area. Add 10% waste (15 tiles) = 165 tiles minimum. For a diagonal layout, add 15β20% instead: 150 Γ 1.17 = 176 tiles.
When tiles are set at 45 degrees, every edge where a tile meets the wall must be cut at an angle. These diagonal cuts produce triangular waste pieces that cannot be reused on the other side of the room. Approximately 15β20% more tiles are needed compared to a straight grid layout.
Porcelain tiles are denser, less porous, harder, and more resistant to water and frost than ceramic tiles. Porcelain is made from refined clay fired at higher temperatures (around 1300Β°C vs 1000Β°C for ceramic). Porcelain is better for outdoor use, wet rooms, and high-traffic floors. Ceramic is lighter, easier to cut, and usually cheaper β fine for dry bathroom walls and light-traffic floors.
For a standard bathroom floor of 6 mΒ² tiled with 300Γ300mm ceramic tiles using a 6mm notched trowel: approximately 3β4 kg per mΒ² = 18β24 kg total. One 20 kg bag is usually sufficient with some left over. For larger tiles or uneven substrates, you may need a second bag.
Yes, particularly for floor grout and grout in wet areas. Unsealed grout absorbs water, soap scum, and mould spores. Apply a penetrating grout sealer after the grout has fully cured (at least 48 hours, ideally 72 hours). Re-seal annually in showers and bathrooms. Wall grout above the waterline is less critical but still benefits from sealing.
In the UK, porcelain tiles rated R10 or higher (slip resistance) are best for bathroom floors. Popular sizes are 300Γ300mm and 600Γ600mm. Rectified large-format tiles with 2mm joints give a contemporary look but require a perfectly flat subfloor. For a traditional look, encaustic cement tiles or small mosaic tiles are popular choices in period UK properties.
Tile retailers sell tiles by the box (or pack), and each box covers a stated area. Always round up to whole boxes. If you need 22 mΒ² of tiles and boxes cover 1.44 mΒ² each, you need 22 Γ· 1.44 = 15.28 boxes β order 16 boxes. Then calculate the exact tile count from the box contents to double-check you have enough for your layout plus waste.
Disclaimer: Tile quantity estimates are guides only. Always verify measurements on site and consult product data sheets for adhesive and grout coverage. Tile requirements vary by room shape, layout complexity, and wastage during cutting.