Tile calculator for floors, walls and showers

Buy 10% extra for a straight layout and 15% for diagonal or for a first tile job. Those are trade rules of thumb, not a code figure: a tile distributor's general advice is 10% to 15%, and installers on a DIY forum put pros at about 10% and beginners at about 15%. Go higher for herringbone, rooms with many angles, large or fragile tile, and tile you cannot reorder. The extra covers cuts, breakage and spares for later repairs. Enter the percentage in the calculator and it applies it once to the exact count, then rounds up.

Square footage of the area ÷ square feet per tile, plus 10% to 15%, rounded up. The step-by-step version with floors, showers and backsplashes is in how much tile do I need.

Because 12 × 12 in is a nominal size, and the box size is meant to include the grout joint. A tile sold as 12 × 24 in can measure 11 11/16 × 23 7/16 in, and tilers on forums report the same gap on square tiles. Sizes can also vary a little between lots and even within a box, which is why the joint has to be at least three times that variation under ANSI A108.02. For ordering, count on the label size. If you measure a real tile, use the measured size mode and add your joint.

Yes, always round boxes up. If the count needs 15.6 boxes, buy 16; rounding down leaves the job short, and a forum thread asking this exact question had a reply that made that mistake. Divide your tile count, waste included, by the tiles per box, or divide the square footage of tile by the square feet per box. In the calculator, pick which one the carton prints and it rounds up for you. For example, 53 tiles at 6 per box is 8.83, so 9 boxes.

Keep a few loose tiles for small jobs and about one unopened box for a large floor, though there is no fixed rule. Homeowners on forums answer this anywhere from a handful of tiles to a full box. The point is repairs: a cracked tile years later needs a replacement from the same production lot, and tile lines get discontinued or change shade. Store the spares flat in their box with the lot number visible. That reserve is part of why a 10% to 15% waste allowance is normal.

Sometimes, but do not count on it. Tilers on a trade forum describe sellers refusing returns on special orders and on opened boxes, and some set a short return window. Ask before you buy, keep receipts, and leave spare boxes sealed. Even when returns are allowed, buying a little extra up front is safer than reordering later, because a new order may come from a different lot with a different shade or caliber. Leftover tile has little resale value, so treat a returnable sealed box as a bonus.

Yes, if the size you count from is the tile's real measured size. Each tile then occupies its size plus the joint, so a wider joint covers more area per tile. The effect matters for small tile: 4 × 4 in tile needs about 6% fewer pieces with a 1/8 in joint than with none. On 24 × 24 in tile it is about 1%. If you count from the box label, do not add the joint at all, because the label size already allows for it. The calculator only asks for the joint in measured mode.

Plan on about 15% for a diagonal layout and 20% or more for herringbone, against about 10% for a straight lay. These are rules of thumb; installers' forums have long threads on the question. Diagonal cuts every edge tile into triangles that rarely fit elsewhere, and herringbone needs an angle cut at both ends of every run along every wall. Small rooms waste proportionally more. Set the pattern in the calculator and it warns you when the waste you entered is below the usual figure for that layout.

Add the walls, then divide by the tile area. A 5 ft back wall and two 2 ft 8 in side walls, 8 ft tall, total 82.7 sq ft. In 3 × 6 in subway tile, which is 8 tiles per sq ft, that is 662 tiles before waste and 761 with 15%. Add a niche as an extra area: a 12 × 24 in niche 4 in deep adds 4 sq ft. Count the shower floor separately, because it is usually a small mosaic that comes in sheets. Edge pieces such as bullnose are sold by the linear foot.

50 tiles before waste, because each 12 × 24 in tile covers 2 sq ft. With 10% waste that is 55 tiles, with 15% it is 58, and for a herringbone at 20% it is 60. Long tile laid in a running bond should also follow the 33% offset limit for tiles over 18 in, which can raise the waste slightly. Check the box: a carton that holds 8 pieces covers 16 sq ft at label size, so 55 tiles is 7 boxes. The chart above lists the same counts for eleven common sizes.

It depends on the product, so read the carton. The label lists pieces per box, square feet per box, or both. Small tile comes in more pieces per box: one 3 × 6 in glass subway product ships 40 pieces covering 5 sq ft. Large porcelain might be 8 pieces of 12 × 24 in, or two or three pieces of 24 × 24 in. If a label gives both numbers, multiply pieces by tile area to check it. The calculator takes whichever number the carton prints and rounds to whole boxes.

A 2 × 2 ft tile (24 × 24 in) covers 4 sq ft, so 100 sq ft needs 25 tiles before waste and 28 with 10%. If you mean 2 × 2 in mosaic, each chip covers 4 sq in, or 1/36 sq ft, and mosaic is sold in mesh-backed sheets, so you count sheets rather than chips. For a sheet product, enter the sheet size as a custom tile size and the calculator counts sheets. Read the sheet size off the label, since it varies by product.

1/16 in. ANSI A108.02 (2019 edition, §4.3.8) says the joint must be at least three times the tile's actual size variation and never less than 1/16 in. For tile with any side over 15 in it sets about 1/8 in on average for rectified tile and 3/16 in for calibrated tile. A tile that varies by 1/16 in therefore needs at least 3/16 in. Ask for the variation on the product data sheet. Tighter joints than the tile allows show up as crooked lines and uneven edges once the tile is down.

Not reliably. Tile is made in production lots, and shade and size can change from one lot to the next even for the same product code. Homeowners on design forums who reordered for a repair found the new tile did not match. Buy the whole job at once, check that every carton shows the same lot or shade code before you open it, and blend tiles from several boxes as you lay them. That is the strongest case for a waste allowance: the extra is your only guaranteed match.

The notch size follows the tile size and the floor flatness, and coverage must reach 80% in dry areas and 95% in showers under ANSI A108.5. Notch sizes and thinset quantities by tile size are in trowel size, thinset and mortar for tile.