Shower Tile Calculator — Walls, Floor, Curb and Niche
A shower is five surfaces, not one, and the things that go behind the tile cost as much as the tile. This counts walls, floor, curb, ceiling and niche, and the backer board and membrane underneath them.
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How to work it out
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Measure the opening, not the tile
Width is the back wall, depth is front to back. For a standard alcove built to take a bathtub that is usually 60 by 32 inches, but measure rather than assume — a shower built into an old bathroom is whatever size the space allowed.
Measure to the framing if the walls are open, or to the face of the existing surface if they are not. The difference is the backer board thickness, about half an inch.
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Decide how high the tile goes
Eighty-four inches is the common stopping point — seven feet, roughly where the shower head sits plus a course or two. Running to the ceiling costs perhaps 15% more tile and looks considerably better, with no awkward transition line to keep level.
If you are tiling over a tub, measure from the tub deck rather than the floor. The tub is typically 14 to 20 inches up and the tile does not go behind it.
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Count the surfaces people forget
The curb has three tiled faces: the top, the outside and the inside. A recessed niche has a back, two sides, a top and a shelf. The shower floor usually gets mosaic because small tiles follow the slope to the drain without lippage.
Each of these is small, and together they are several square feet and a surprising amount of cutting. They are also where the trim pieces go, which often have a separate lead time.
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Budget for what goes behind it
Tile is not waterproof and neither is the grout between it. The waterproofing is a separate layer behind the tile — either a sheet membrane bonded over the backer board, or a liquid painted on in two coats.
Regular drywall does not belong in a shower at all. Cement backer board or a foam panel goes on the framing first, then the membrane, then the tile. Skipping that layer is the single most expensive mistake in a bathroom.
Shower wall area by size
Three walls tiled, before the floor, curb and niche.
| Shower size | Tile to 72 in. | Tile to 84 in. | Tile to 96 in. |
|---|---|---|---|
| 60 × 30 in. | 60.0 sq ft | 70.0 sq ft | 80.0 sq ft |
| 60 × 32 in. | 62.0 sq ft | 72.3 sq ft | 82.7 sq ft |
| 60 × 36 in. | 66.0 sq ft | 77.0 sq ft | 88.0 sq ft |
| 48 × 36 in. | 60.0 sq ft | 70.0 sq ft | 80.0 sq ft |
| 36 × 36 in. | 54.0 sq ft | 63.0 sq ft | 72.0 sq ft |
| 72 × 42 in. | 78.0 sq ft | 91.0 sq ft | 104.0 sq ft |
Add roughly 7 sq ft for a shower floor at 60 × 32, 3 sq ft for a 6 in. curb, and 2 sq ft per niche.
What goes behind the tile
Coverage for the layers under the surface.
| Material | Sold as | Covers |
|---|---|---|
| Cement backer board | 3 × 5 ft sheet | 15 sq ft |
| Foam backer panel | 3 × 5 ft sheet | 15 sq ft |
| Sheet membrane | Roll | Check the roll — commonly 108 or 323 sq ft |
| Liquid membrane | 1 gal bucket | 35–50 sq ft at two coats |
| Thinset | 50 lb bag | 80–95 sq ft at a 1/4 in. notch |
| Grout | 10 lb bag | About 40 sq ft of 12 in. tile at 1/8 in. joints |
Large-format tile needs a bigger trowel notch, which cuts thinset coverage by a third or more.
How much tile for a standard 60x32 shower?
Three walls at 60 by 32 inches, tiled to 84 inches high, is a run of 60 + 32 + 32 = 124 inches. Times 84 and divided by 144 gives 72.3 square feet of wall.
Add the floor at 13.3 sq ft, a 6 inch curb at 6.7 sq ft, and one niche at about 2 sq ft, and the total is roughly 94 square feet. With a 15% allowance that is 108 sq ft to buy — 109 twelve-inch tiles, or 868 subway tiles.
Underneath it: five sheets of backer board, 102 sq ft of waterproofing, two bags of thinset and three bags of grout.
Backer board, membrane, and why both
These do two different jobs and you need both. Backer board is the substrate — a rigid, dimensionally stable surface that will not soften or rot if it gets damp, and that thinset will actually bond to. Cement board and foam panels both qualify. Ordinary drywall does not, and green board is only moisture-resistant, not waterproof.
The membrane is the actual waterproof layer, and it goes on top of the backer board, behind the tile. Sheet membranes bond down with thinset and their seams are taped; liquid membranes are rolled or brushed on in two coats to a specified thickness. Foam panels sold as part of a system are already waterproof and need only their seams treated.
Water gets through grout. It always has. The membrane is what stops it reaching the framing, and it is the difference between a shower that lasts thirty years and one that rots out the wall in five.
Why the shower floor is almost always mosaic
A shower floor slopes to the drain, and it slopes in more than one direction at once — the surface is faceted, not flat. A large tile is rigid and cannot follow that shape, so it either rocks or leaves lips between tiles that catch your feet and hold water.
Small tiles on a mesh sheet, typically two inches or smaller, flex over the slope because each one sits independently. That is the reason mosaic dominates shower floors, not fashion.
More joints also means more grip, which matters in a wet space. The trade-off is far more grout: a mosaic floor uses several times the grout of the same area in large tile, and it needs sealing if the grout is cement-based.
The niche, the curb and the trim
A recessed niche is one of the fiddliest parts of a shower. The box has a back, two sides, a top and a bottom shelf, and every one of those is a cut piece. It also needs waterproofing like any other part of the enclosure, sloped slightly so water runs out rather than sitting on the shelf, and a finished edge all the way round.
The calculator adds roughly two square feet per niche, which covers the lining. What it cannot count for you is the trim: bullnose, a metal profile, or mitered tile edges. Measure the niche perimeter and order that separately.
The curb is three faces — top, outside, inside. At 60 inches wide and 6 inches high that is about seven square feet, and it is one of the hardest bits to waterproof because it has corners going in every direction. Pre-formed curbs that come with the waterproofing system are worth the money.
Thinset: the trowel decides the coverage
A 50 lb bag of thinset covers 80 to 95 square feet with a 1/4 inch square-notch trowel, which suits tile up to around 8 inches. Move to 12 inch tile and you want a 1/4 by 3/8 in. notch, and coverage drops to roughly 60 sq ft. Large-format tile at 12 by 24 or bigger needs a 1/2 inch notch, and a bag might do 40.
So the same shower can need two bags or four depending entirely on the tile you picked. The calculator uses the standard 1/4 inch figure; if you are going large-format, assume you need close to double.
Buy the right thinset as well as the right amount. Large-format tile needs a medium-bed or LFT mortar that does not slump. Glass and some stone need white thinset so the color underneath does not show through.
Order one extra box, deliberately
Shower tile is made in batches and the batches do not match. Dye lot variation in ceramic and shade variation in stone are both normal, and a replacement box bought six months later will be visibly different in a space this small and this well lit.
Check the lot number is the same on every box before you leave the store, and buy one more than the calculator says. Keep it in the box, somewhere dry, labeled with the room.
The other reason is breakage during cutting. Shower tile gets cut around a valve, a shower head, a niche and every corner, and the cuts around round penetrations break more often than straight cuts do. Fifteen per cent covers a normal rate; if the tile is large-format and thin, allow more.
How this is worked out
No black box — here is the arithmetic the calculator runs, so you can check it against your own numbers.
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wall run = width + 2 × depth (for a 3-wall alcove)A back wall and two returns; the fourth side is the glass. -
wall area = run × height ÷ 144All the inputs are inches, so divide by 144 for square feet. -
+ floor = width × depth ÷ 144Only if the shower has a tiled pan rather than acrylic. -
+ curb = width × (2 × curb height + 4) ÷ 144Top, outside and inside faces, with a 4 in. top. -
+ 2 sq ft per nicheBack, sides, top and shelf once the box is lined. -
× (1 + waste ÷ 100)15% standard — corners, the valve and the niche all cut. -
backer board = wall area ÷ 15A 3 × 5 ft sheet is 15 sq ft. -
grout = area ÷ 40, in 10 lb bagsRoughly double the rate for a plain 12 in. floor, because a shower has a mosaic pan and a niche — far more joint length per square foot. -
waterproofing = (walls + floor + curb) × 1.1Every wet surface, plus 10% for overlaps at the seams.
Common questions
How many square feet of tile for a standard shower?
A 60 by 32 inch alcove tiled to 84 inches on three walls is about 72 sq ft of wall. Add the floor, a curb and a niche and the total is roughly 94 sq ft, or 108 sq ft once you allow 15% for waste.
Can I tile over green board in a shower?
No. Green board is moisture-resistant paper-faced gypsum, not a waterproof substrate, and it has not been permitted in wet areas of a shower for a long time. Use cement backer board or a foam panel, then a waterproof membrane over it.
Do I need waterproofing if I use cement board?
Yes. Cement board does not rot, but it is not waterproof — water passes straight through it. The membrane over it is what keeps water out of the framing. Some foam panel systems are waterproof in themselves and only need their seams sealed.
How high should shower tile go?
Eighty-four inches is the usual stopping point. Running to the ceiling costs around 15% more tile, removes the horizontal line, and is easier to keep straight. Over a tub, measure from the tub deck, not the floor.
What size tile for a shower floor?
Two inches or smaller, on mesh sheets. The floor slopes toward the drain in more than one direction, and only small tiles can follow that shape without rocking or leaving lips. It also gives more grip underfoot.
How much thinset do I need for a shower?
Two 50 lb bags for a typical shower with tile up to 8 inches, using a 1/4 in. notch trowel. Twelve inch tile needs a bigger notch and roughly 50% more; large-format tile can need double.
Should I tile the shower ceiling?
Only for a steam shower or a fully enclosed one, where the ceiling gets genuinely wet. In a normal shower a good moisture-resistant paint and decent ventilation are enough, and a tiled ceiling is difficult to install and awkward to clean.
How much extra tile should I buy?
Fifteen per cent for a standard shower, plus one full box kept back. Dye lots do not match between batches, and in a space this small and this brightly lit, a mismatched replacement tile is obvious from the doorway.
Where these figures come from
Every figure below is traceable. How we check the numbers explains how they are verified, and the coverage reference collects them all in one place.
- Tile Council of North America handbook, methods B415 and B421 — shower receptor and wall waterproofing assemblies
- ANSI A118.10 — the standard bonded waterproof membranes are tested against
- Manufacturer coverage charts — thinset coverage by trowel notch and backer board sheet sizes
Think a number here is wrong? Tell us — we check every report, correct the page, and date the change. Last checked September 12, 2026.