Shower Tile Calculator: How Much Tile You Need

Every week someone asks me to eyeball how many boxes their shower needs, and every week the honest answer is the same: five minutes with a tape measure beats any guess. A shower tile calculator is really just three pieces of arithmetic — wall area, floor area, and a waste factor that depends on your tile size and pattern — and once you understand the method you can price any shower in your head at the tile store. I will walk through the exact math I use to order material, run a full worked example on a standard shower, and give you the waste percentages that keep you from a second trip or a garage full of leftovers.

Part of our Bathroom Remodeling & Flooring guide — explore the full guide →

The basic formula

For each surface: length × height (or width) in feet gives square feet. Add all surfaces, subtract large openings, then multiply by your waste factor. In formula form:

• Wall area = sum of (wall width × tiled height) for each wall
• Minus the door or opening area (only if it is large; I skip this subtraction on small openings and bank it as extra waste allowance)
• Plus floor/pan area = length × width
• Plus extras: curb (all faces), niche (back, sides, shelves), bench (top and face), ceiling if tiled
• Order quantity = total × (1 + waste %) , rounded up to whole boxes

Measure in inches, divide by 12 to get feet, and keep one decimal. Tile boxes state coverage in square feet on the label, typically 8 to 15 square feet per box depending on tile size.

Worked example: a standard 36 x 60 inch alcove shower

Take the most common US configuration: a 60 inch wide alcove, 36 inches deep, tiled to 96 inches (8 feet) high on three walls, with a glass panel and door across the front. Tile is 12×24 porcelain on the walls, 2-inch mosaic on the pan.

1. Back wall: 60 in × 96 in = 5 ft × 8 ft = 40.0 sq ft
2. Two side walls: 36 in × 96 in = 3 ft × 8 ft = 24.0 sq ft each, so 48.0 sq ft
3. Wall subtotal: 88.0 sq ft
4. Pan: 5 ft × 3 ft = 15.0 sq ft
5. Curb: 5 ft long, three faces roughly 4 in + 4 in + 4 in = 12 in total wrap = 5 ft × 1 ft = 5.0 sq ft
6. Niche: a 12×24 niche with 4 in depth adds its back (2.0 sq ft) plus sides and shelf, call it 3.5 sq ft — and remember the niche back does not reduce your wall count in practice, because the cutout pieces are rarely reusable
7. Raw total: 88.0 + 15.0 + 5.0 + 3.5 = 111.5 sq ft

Now waste. With 12×24 tile set in a 1/3 offset, I use 15 percent on a shower because every wall in a 36-inch-deep stall involves cuts on both ends, plus valve and niche cutouts. Walls plus curb: 93 × 1.15 = 107.0 sq ft of 12×24. Mosaic pan at 10 percent: 15 × 1.10 = 16.5 sq ft, and mosaic sheets usually sell by the square-foot sheet, so buy 17 sheets. Niche in the field tile is inside the 15 percent. If boxes hold 15.5 sq ft, that is 107 ÷ 15.5 = 6.9, so seven boxes.

Waste factors by tile size and pattern

Waste is where most online calculators fail you, because they default to 10 percent for everything. Real waste depends on how many cuts your layout forces and how many of the offcuts are reusable. These are the numbers I actually order with:

Add another 5 percent on top of anything above if you are a first-time setter. Cheap insurance: a broken tile at 9 p.m. on a Sunday is worth a lot more than the $4 it cost.

Do not forget the pan slope and the small surfaces

A shower pan is not flat; it slopes to the drain at roughly 1/4 inch per foot. On a residential pan the extra area from slope is under 2 percent, so ignore it, but do use mosaic or tile 4 inches or smaller on a traditional sloped pan so the pieces can follow the compound curve without lippage. Linear-drain pans with a single plane can take large tile.

The surfaces people forget, in the order I see them forgotten: the curb’s inside face, the ceiling above steam showers (add length × width if tiled), bench faces and the waterfall edge of the bench top, the jamb returns where tile wraps into a doorless entry, and trim. Bullnose or metal edge profile is ordered by the linear foot, not square foot; measure every exposed tile edge, typically the vertical front edges of both side walls plus the curb, so around 20 to 22 linear feet on our example shower.

Converting square feet to boxes, sheets, and pieces

Retail tile sells three ways. Field tile sells in boxes; divide your waste-adjusted square footage by the box coverage and round up. Mosaics sell per sheet, usually 0.9 to 1 square foot each; divide and round up per sheet. Specialty pieces (bullnose, pencil, chair rail) sell per piece; divide linear feet needed by piece length in feet and round up, adding two or three spares for miters and breakage. Always check the box: “12×24” tile boxes range from 12.5 to 16.3 square feet depending on brand and pieces per carton.

One buying rule I insist on: purchase everything from one dye lot (check the shade and caliber codes printed on the boxes match) and keep one unopened box until the job is done and inspected. Most stores accept unopened-box returns within 30 to 90 days, so overbuying by one box is free insurance, while underbuying risks a lot mismatch that no grout color can hide.

Quick reference: common shower sizes

Using 8-foot wall height, three tiled walls, pan, and a 5 sq ft curb/niche allowance, before waste:

• 32×32 corner stall: walls ~64 sq ft, pan 7.1 sq ft, total ≈ 76 sq ft
• 36×36 stall: walls ~72 sq ft, pan 9 sq ft, total ≈ 86 sq ft
• 36×60 alcove: walls 88 sq ft, pan 15 sq ft, total ≈ 108 sq ft
• 42×60: walls 92 sq ft, pan 17.5 sq ft, total ≈ 115 sq ft
• 48×72 walk-in: walls ~104 sq ft, pan 24 sq ft, total ≈ 133 sq ft

Multiply by your pattern’s waste factor and you have an order quantity that any tile shop will recognize as a pro’s number.

Estimating setting materials while you are at it

Since you already have the square footage, price the rest of the job: thinset covers roughly 40 to 50 square feet per 50-pound bag with a 1/4×3/8 notch trowel (large-format tile with heavier troweling, closer to 30 to 35), so our 108 sq ft example shower needs about three bags at $15 to $45 each depending on modification. Grout runs about 100 to 150 square feet per 10-pound bag with 12×24 tile and 1/8 inch joints, but mosaics drink grout — figure 40 to 60 square feet per bag on a 2-inch mosaic pan. Waterproofing membrane, backer, and fasteners are sized by the same wall areas you just calculated.

The takeaway method, compressed: measure each surface, sum it, apply an honest pattern-based waste factor, round up to whole boxes from one dye lot, and keep a spare box unopened. Run your numbers through any shower tile calculator online afterward as a sanity check if you like, but if its answer differs from yours, trust the tape measure and your waste factor over a form field that assumed 10 percent. Five careful minutes here saves the two worst outcomes in tiling: the dye-lot hunt mid-job, and paying to store 60 square feet of tile you will never use.