How many tiles do I need? Tile and box calculation for walls and floors, with examples

Ordering tiles is a sum, and it goes wrong in the same few ways: a wall measured without its door, no allowance for cut tiles, or boxes of two different shades because the first order fell short. This guide shows the calculation step by step, in square feet and in square metres, with worked examples for a bathroom, a kitchen backsplash, a feature wall and a floor.

The numbers use our three tile sizes, 300 × 300 mm, 300 × 450 mm and 300 × 600 mm, but the method works for any tile. If you would rather not do the sum yourself, send us the room sizes and we will work out the boxes for you.

The short version

1. Measure the area to be tiled: width × height for each wall, length × width for a floor.
2. Subtract doors, windows and anything built in that will not be tiled.
3. Add a wastage allowance, usually 10%.
4. Divide by the coverage of one box and round up to a whole box.

That is the whole method. The rest of this guide explains each step, because each one has a trap.

Tiles and boxes by size

These are the numbers you need for the last step. Box coverage in square feet is the figure printed on the box; in the trade a 12 × 12 inch tile counts as 1 sq ft.

A note on that coverage figure: 300 mm is 11.8 inches, not 12, so a box really covers about 3% less than the square feet on its label (6.8 sq ft rather than 7 for the 300 × 300 mm box). The joint between tiles makes up a little of the gap, and a normal wastage allowance covers the rest. It is one more reason not to cut the allowance below 8%.

Melisa Art Moroccan 300 × 300 mm

Mudy Stone Exterior Design 300 × 450 mm

Velveno Wall Concept 300 × 600 mm

Step 1: measure the area

Measure in feet if you will order in square feet, and in metres if you will order in square metres. Do not mix the two in one sum.

• A wall. Width × the height you will tile. The height is not always the ceiling: bathrooms are often tiled to 7 feet (about 2.1 m), and kitchen backsplashes only between the counter and the wall cabinets.
• A room's walls. Add the widths of all the walls (the perimeter) and multiply by the height. For a rectangular room that is 2 × (length + width) × height.
• A floor. Length × width. Split an L-shaped room into two rectangles and add them.
• Odd shapes. A sloping wall under a staircase is a triangle: half of width × height. An arch or a curve can be measured as the rectangle around it; the extra becomes your wastage.

Measure each wall at two or three heights, because walls are rarely perfectly square, and use the largest figure.

Step 2: subtract openings

Subtract doors and windows, and anything fixed that will not be tiled behind: a built-in wardrobe, a kitchen's tall unit, a mirror that is fixed before tiling.

Measure your own openings rather than using these: they are only typical sizes. Small openings, such as a ventilator, can be left in the sum; the tiles around them need cutting anyway, so the extra goes to wastage.

Step 3: add wastage

Some tiles are cut at the edges, corners, pipes and switches, some offcuts are too small to use, and a tile or two may break. The usual allowance:

On top of the allowance, keep one spare box of every design in the house. If a tile cracks years later, a spare from the same batch will match; a tile bought later may not, because every firing batch has its own shade.

Step 4: convert to boxes

Divide the area with wastage by the coverage of one box, and always round up. In square metres, use the actual coverage from the table above.

For pattern sets, work out each tile separately. In a set of a plain base and a decor tile, decide first how much of the wall the decor covers (a band, a panel or a whole wall), work out that area, and give the rest to the base. The highlighter tiles guide has the usual proportions.

Worked example 1: a bathroom

A bathroom 5 × 7 feet, walls tiled to 7 feet, with a 2.5 × 7 ft door and a 2 × 1.5 ft window.

• Walls: 2 × (5 + 7) × 7 = 168 sq ft
• Less the door (17.5) and window (3): 168 - 20.5 = 147.5 sq ft
• Plus 10%: 147.5 × 1.1 = 162.25 sq ft
• In 300 × 450 mm tiles: 162.25 ÷ 7.5 = 21.6, so 22 boxes
• In 300 × 600 mm tiles: 162.25 ÷ 8 = 20.3, so 21 boxes
• Floor: 5 × 7 = 35 sq ft, plus 10% = 38.5 sq ft, in 300 × 300 mm tiles: 38.5 ÷ 7 = 5.5, so 6 boxes

If the shower wall gets a decor panel, work out the panel first (for example 3 × 7 ft = 21 sq ft, plus 12%, is 23.5 sq ft, or 4 boxes of 300 × 450 mm) and take the panel's area off the base tile's area before converting it. Our bathroom wall tiles guide covers layouts and heights.

Graph Wall Concept 300 × 300 mm

Marmi 300 × 300 mm

BW 01 Black-White 300 × 300 mm

Worked example 2: a kitchen backsplash

A straight kitchen counter 10 ft long, tiled 2 ft high between the counter and the wall cabinets, with a 3 ft wide chimney area tiled a further 2 ft up to the hood.

• Backsplash: 10 × 2 = 20 sq ft
• Chimney area: 3 × 2 = 6 sq ft
• Total 26 sq ft, plus 10% = 28.6 sq ft
• In 300 × 450 mm tiles: 28.6 ÷ 7.5 = 3.8, so 4 boxes

For an L-shaped kitchen, add the second run of counter in the same way. Remember the strip beside a tall fridge or larder unit if it will be visible. More in the kitchen wall tiles guide.

Willow Kitchen Kitchen Studio 300 × 450 mm

Mailono Zapta Kitchen Studio 300 × 450 mm

Pigmento Aqua 300 × 300 mm

Worked example 3: a living room feature wall

A wall 12 ft wide and 10 ft high behind a TV, with no openings, in 300 × 600 mm tiles.

• Area: 12 × 10 = 120 sq ft
• Plus 10%: 132 sq ft
• 132 ÷ 8 = 16.5, so 17 boxes

A plain wall with few cuts could use 5% (16 boxes), but a feature wall is the one place you do not want to run out: the replacement box may come from a different batch, and on a feature wall the difference shows. See living room wall tiles for designs.

Chevron Wall Concept 300 × 600 mm

Qubonic Wall Concept 300 × 600 mm

Belfist Wall Concept 300 × 600 mm

Worked example 4: a floor

A room 10 × 12 feet in 300 × 300 mm floor tiles.

• Area: 10 × 12 = 120 sq ft
• Plus 10%: 132 sq ft
• 132 ÷ 7 = 18.9, so 19 boxes

If the floor tile also runs up the wall as a skirting, add the skirting: the room's perimeter × the skirting height. A 4 inch (one third of a foot) skirting around this room is 44 ft × 0.33 ft, about 15 sq ft. Each 300 mm tile cuts into three 4 inch strips, so that is about 15 tiles, or 3 more boxes.

Kolum Multi Signature Floor 300 × 300 mm

Porto Fatima Moroccan 300 × 300 mm

Elton Craft Exterior Design 300 × 300 mm

Worked example 5: in square metres

A wall 3 m wide and 2.4 m high, in 300 × 450 mm tiles.

• Area: 3 × 2.4 = 7.2 m²
• Tiles: 7.2 × 7.41 = 53.3 tiles
• Plus 10%: 58.7, so 59 tiles
• 59 ÷ 5 tiles per box = 11.8, so 12 boxes

Or directly: 7.2 m² × 1.1 ÷ 0.675 m² per box = 11.7, so 12 boxes.

How many tiles in 100, 500 and 1,000 sq ft

Quick figures before wastage, using the box coverage printed on the box:

Add your wastage allowance to the area first, then read the boxes. For 1,000 sq ft of bathroom walls at 10%, that is 1,100 sq ft, or 147 boxes of 300 × 450 mm.

Units and conversions

Tile sizes in India are given in millimetres, rooms are usually measured in feet, and export orders are often in square metres. These conversions cover most sums:

And the tile sizes themselves: 300 mm is 11.8 inches (sold as 12 inch, or 1 ft), 450 mm is 17.7 inches (sold as 18 inch, or 1.5 ft) and 600 mm is 23.6 inches (sold as 24 inch, or 2 ft).

How many tiles across and up: setting out a wall

The count of boxes is one sum; how the tiles fall on the wall is another, and it decides how good the wall looks. Divide the wall by the tile plus one joint to see how many fit.

• Across. A wall 7 ft wide is 2,134 mm. A 300 mm tile with a 2 mm joint takes 302 mm, so 7 tiles fit with a 20 mm sliver left over. A sliver that thin looks like a mistake and is hard to cut. Instead, lay 6 full tiles in the middle and cut the two end tiles to about 160 mm each, so both corners match.
• Up. The same wall tiled to 7 ft in 300 × 450 mm tiles laid upright (452 mm with the joint) takes 4 full rows and a cut row of about 325 mm. Laid on their side (302 mm a row) it takes 7 rows and a 20 mm sliver. Here it is better to stop the tiling at 7 full rows, about 6 ft 11 inches, than to add a sliver at the top.

Choose the tiled height to finish on a full tile wherever you can. It costs nothing and makes the top edge clean. Plan the starting row so cut tiles go where they are least seen: behind a door, at floor level under a skirting or in a corner.

A tile schedule for a whole house

For a full house or a project, list every surface in a table before you order. It keeps base tiles, decors and floor tiles apart, and it is what our team works from when we prepare a quotation.

The bathroom rows are the first worked example split into base and decor: the 147.5 sq ft of walls less the 21 sq ft panel leaves 126.5 sq ft of base, which is 139.2 sq ft with wastage, or 19 boxes. Add a spare box per design at the end, and order everything at once.

Emola Wall Concept 300 × 300 mm

Divyam God Divine Space 300 × 450 mm

Delice Bricks 300 × 450 mm

Adhesive and grout

Tile adhesive and grout are usually bought with the tiles, and they are easy to run short of on site.

• Adhesive. A 20 kg bag of cement-based tile adhesive typically covers about 40 to 60 sq ft of wall tiles, depending on the trowel notch and how flat the wall is. The bag gives the exact figure for each notch size. Uneven walls take more.
• Grout. With 2 mm joints, our calculation for these sizes comes to roughly 50 to 80 sq ft of wall per 1 kg of cement grout: about 50 sq ft for the 9.5 mm thick 300 × 300 mm tile, about 70 sq ft for 300 × 600 mm and about 80 sq ft for the thinner 300 × 450 mm tile. Wider joints use proportionally more. Buy a little extra of the same colour for later touch-ups.

Our guide to installing wall tiles explains adhesive, joints and grout in full.

Mistakes that make orders fall short

• Measuring the floor but forgetting the skirting. It adds 10 to 15% to a small room.
• Leaving out the wastage. Every room needs cut tiles.
• Rounding down. 21.6 boxes is 22 boxes.
• Ordering in two lots. Order the full quantity at once, so every box is from the same batch.
• Forgetting the spare box. Keep one per design for repairs.
• Mixing units. Feet and metres in the same sum produce numbers ten times too big or too small.

Let us work it out

Send us your room sizes, the tiled height and the openings, or a simple sketch, with the designs you like. We will work out the boxes for each design, including the base and decor tiles of a set, and include them in your quotation. Architects and builders can send a whole schedule of areas; see tiles for architects and interior designers. The tile sizes guide explains which size suits which wall.

Wall Concept Designer pattern wall tiles · 10 designs Kitchen Studio Kitchen wall and backsplash tiles · 2 designs

Contact us with your measurements, or browse every design by size: 300 × 300 mm, 300 × 450 mm and 300 × 600 mm.