How to work out how much tile you need
Measure every surface that gets the same tile: the floor, each wall of the shower or tub up to the height you'll tile, a backsplash. Then take out what won't be tiled, like the tub, a vanity that sits on the subfloor, an island or a window.
Each tile covers its face plus one grout joint in each direction. A 12x24 tile with 1/8 inch joints takes up 12 1/8 by 24 1/8 inches. That's 292.5 square inches, or 2.03 square feet, since a square foot is 144 square inches. Leave the joint out and the count comes in a little high. The difference grows as the tile gets smaller.
87.5 sq ft of 12x24 tile comes to 6 boxes
How much extra tile to order
We found no industry standard for how much extra to order, and the advice varies a lot. For a straight layout, tile sellers, makers and calculator sites say anywhere from 7% to 20%.
The more you cut, the more extra you order
Go above the default when the room has a lot of corners and jogs, when the tile is small or fragile, or when the pattern lines up across walls. Ask your installer what figure fits your job, then type it into the calculator.
Keep spares, too. Daltile suggests buying about 10% more than you expect to need, so you can replace a cracked tile from the same dye lot years later. At the least, keep whatever's left in the last box.
Long tile needs a smaller offset and a wider joint
Rectangular tile over about 15 to 18 inches long tends to bow slightly in the middle. Lay it with each row shifted by half a tile, and the high middle of one tile sits next to the low end of the next. That's why the tile installation standard, ANSI A108.02, caps a brick offset at 33% for long tile unless the tile maker says otherwise. MSI tells installers to use a one-third offset on plank tile, not a half.
The joint matters too. For long tile in a brick layout, the standard asks for joints that average at least 1/8 inch on rectified tile, which is cut to a precise size, and 3/16 inch on tile that isn't. No joint should be narrower than 1/16 inch. Use the joint the tile maker lists for your tile, and set it in the calculator so the count matches.
Price the tile job
In our planning model, new tile for a 50 sq ft bathroom comes to $9,100, labor included. The bathroom remodel cost calculator prices a tile-only job: the shower walls, the floor or both. Tiling a kitchen floor as part of a bigger job? Use the kitchen remodel cost calculator. To measure each room first, use the square footage calculator. More free tools are on the tools page.
Who buys the tile and where the backsplash stops are the small decisions that change a bid. If the tile is part of a bigger remodel, the free readiness assessment names the open decisions in your scope and gives you a preliminary room-by-room estimate before you ask contractors for bids.
Questions people ask
Is 12x24 tile too big for a shower?
We haven't found a tile maker that caps tile size for a shower. The shower floor is the part to plan: it slopes toward the drain, typically about 1/4 inch per foot. Schluter makes a linear drain for a floor that slopes in one direction, which suits large tile. Ask your installer which drain and slope your tile needs before you buy the tile.
What is the 3/4/5 rule for tile?
It's a way to check that a corner is square, meaning two layout lines meet at 90 degrees. It's not a way to count tile. Measure 3 feet along one line and 4 feet along the other. If the diagonal between those two marks is exactly 5 feet, the corner is square.
How many 12x12 tiles do I need for a 10x10 room?
The room is 100 square feet. With 1/8 inch joints, each tile covers a little more than 1 square foot, so about 98 tiles cover it. With 10% extra, order 108.