Understanding your result
The headline is the boxes of wall tile to buy, with the tiles to order and the area to tile beside it. The breakdown starts with the walls: their total run, the gross area, the openings you subtracted and the net area that will actually be covered. From there it is the same chain as the floor tile calculator: area per tile with its joint, tiles before waste, the allowance, tiles to order, tiles per box and boxes.
Two rows deserve a second look. Openings should be the doors and windows only, measured to the outside of the frame or trim, because the tile stops there. If you include a vanity or a tub that the tile runs behind, you will run short. And the waste allowance is a share of the tiles, taken from the layout: 10% for straight and brick, 15% for diagonal, 20% for herringbone.
Watch the notes under the table. If the tiled height does not divide into whole courses, the calculator says so and suggests a cut course at the bottom. If more than half the wall is openings, it suggests a higher allowance. And if the tile is large-format, it reminds you of the one-third offset rule for brick patterns, which exists because large rectangular tiles bow slightly and a half offset puts the high centre of one tile against the low end of its neighbours. For a tub surround or a shower with a niche and a mosaic floor, the shower tile calculator handles all the pieces at once.
How we calculate this
The height you enter is the height of the tiled band, not the room height, so a half-height wainscot is handled by typing 4 ft. The openings are subtracted as a total area, which is accurate for counting tile; where they fall only matters for the cuts, and the allowance covers that. The waste percentages are the ones on the waste factors page, and the guide to tile size and grout joint explains why a 3 × 6 subway tile needs twice the grout of a 12 × 24 for the same wall yet barely changes the waste.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Tile size | 12 × 24 in (30 × 60 cm) | A common wall format for bathrooms; subway (3 × 6 in) is the other default people need, and both are listed on the standard sizes reference |
| Grout joint | 1/8 in (3 mm) | TCNA Handbook and ANSI A108.02 minimums: 1/16 in for rectified, 1/8 in for non-rectified tile |
| Door opening | 21 sq ft (2 m²) | A 36 × 80 in door with its casing is close to 21 sq ft; a 30 in door is about 18 sq ft |
| Waste by layout | 10 / 15 / 20% | Tile manufacturer calculators and installer guidance; see the waste factors page |
| Coverage per box | 16 sq ft (1.44 m²) | Typical for 12 × 24 in tile, 8 pieces per box (manufacturer specification sheets, 2025) |
| Sliver threshold | 2 in | A practical installer threshold: cuts narrower than about 2 in are difficult to make cleanly and look wrong next to a full tile |
Assumptions last reviewed October 7, 2026.
The calculator assumes one tiled height for every wall. A feature wall tiled to the ceiling next to walls tiled to 4 ft is two runs of the calculator. It does not count bullnose or edge trim for the exposed edges; the backsplash calculator and the shower calculator both do that for their situations. And it does not know whether the openings sit mid-wall or at a corner, which changes how many cuts are reusable. The guide to large-format tile covers the lippage and leveling questions that come with 12 × 24 and larger tile on a wall.
Two worked examples
A three-wall tub surround to 8 ft
Walls 5 + 8 + 5 ft (an alcove 8 ft wide with 5 ft returns), tiled 8 ft high, no openings, 12 × 24 tile, 1/8 in joint, straight layout, 16 sq ft boxes.
- Wall run: 5 + 8 + 5 = 18 ft
- Gross area: 18 × 8 = 144 sq ft, nothing to subtract
- Tiles before waste: 144 ÷ 2.031 = 70.9
- Tiles to order: 70.9 × 1.10 = 78
- Boxes: 78 ÷ 8 = 9.75, rounded up to 10 boxes, with 2 tiles spare
Ten boxes is 160 sq ft of tile for 144 sq ft of wall. The spare count is low because 78 is close to a multiple of 8; in a room where it is not, the spare pile is bigger and so is the cost of rounding. The large-format note appears because the tile is 24 in long.
A wainscot of subway tile around a bathroom
Four walls 12 + 10 + 12 + 10 ft tiled 4 ft high, 10 sq ft of door opening within the band, 3 × 6 in tile with a 1/16 in joint, straight brick pattern, 10 sq ft boxes at $22.
- Wall run: 44 ft; gross area 44 × 4 = 176 sq ft; less 10 sq ft = 166 sq ft to tile
- Pitch per tile: 6.0625 × 3.0625 ÷ 144 = 0.129 sq ft
- Tiles before waste: 166 ÷ 0.129 = 1,287.5
- Tiles to order: 1,287.5 × 1.10 = 1,417
- Tiles per box: 10 ÷ 0.125 = 80; boxes 1,417 ÷ 80 = 17.7, rounded up to 18 boxes
- Cost: 18 × $22 = $396, with 23 tiles spare
Fourteen hundred tiles sounds like a lot, but it is 166 sq ft of wall, the same area as a modest floor. Subway tile is cheap per box and the count hardly matters; what matters is the grout, which the grout calculator puts at roughly three times the amount the same wall would take in 12 × 24 tile.
Where to find your inputs
Wall widths. Measure each wall you will tile along the floor or along the top of the tub, corner to corner. For a tub surround, the back wall is the tub length (usually 60 in) and the two end walls are the tub width (about 30 to 32 in).
Tiled height. From the tub deck or floor to where the tile stops. Full-height wet walls are usually 7 to 8 ft; a wainscot is 36 to 48 in.
Openings. Width times height of each door and window, including the casing, added together. Leave out anything the tile runs behind.
Coverage per box. On the box label and the product page. For subway tile the box is often described by piece count (80 pieces) and square feet (10 sq ft); either gives the other.
Common mistakes
- Using the room height instead of the tiled height. The tile usually stops well below the ceiling.
- Subtracting the vanity. Tile runs behind a vanity or a toilet in most jobs. Subtract openings only.
- Forgetting the end walls of a tub. A surround has three walls; the two short ones add a third to the area.
- Half-offsetting large tiles. A 50% brick pattern with 12 × 24 tile produces lippage. Keep the offset to a third.
- Starting full tiles at the tub. If the height is not a whole number of courses, the top course will be a sliver. Plan the cut course at the bottom.
- Ordering trim as an afterthought. Bullnose and edge profiles come in the tile’s dye lot too; order them with the tile.
Questions people ask
- How many tiles do I need for a tub surround?
- A standard 60 inch tub alcove has three walls, 5 + 2.5 + 2.5 ft, usually tiled to 8 ft above the tub deck, which is 80 sq ft with no openings. In 12 × 24 tile with a 1/8 inch joint that is 39.4 tiles, 44 with 10% waste, and 6 boxes of 8. Enter three walls with no openings to see it.
- Do I subtract the door and window?
- Yes, subtract their full area; the tile stops at the frame. A 36 × 80 inch door is 20 sq ft, a 36 × 48 inch window is 12 sq ft. The cuts around them cost a little extra tile, which is why the calculator suggests 15% when openings are more than half the wall.
- What grout joint should I use on a wall?
- Most wall tile is set at 1/16 to 1/8 inch. Subway and other small pressed tiles usually take 1/16 inch; large-format and non-rectified tile take 1/8 inch. The joint changes the count by only 1 to 3% but it changes the grout quantity a lot, so decide it before you buy either.
- How much waste for a brick or offset wall pattern?
- The same 10% as a straight stack, because every course still ends in one cut at each side, and the offcut from one end is often the starting piece of the next course. Herringbone on a wall is 20%, and a diagonal is 15%.
- Why does the result say the top course will be a sliver?
- Because the tiled height divided by the tile course height leaves a remainder under 2 inches. A sliver at the ceiling or the floor looks poor and is hard to cut. Installers either start with a cut course at the bottom so the top and bottom cuts are equal, or move the top edge by half a tile. The tile layout calculator shows the cut sizes.
- Does this calculator do the shower floor or the backer board?
- No. It counts wall tile only. The shower tile calculator adds the floor mosaics, the niche and the trim for a complete shower, and the cement board calculator takes the same wall area for the board, screws and tape under the tile.