Tile Calculator

How to use the tile calculator

Most tile estimates divide the floor area by the area of one tile and add a percentage for waste. That is quick, but it can't tell you how many tiles are cut at the edges, whether the offcuts are any use, or what a diagonal or herringbone layout really costs. This tile calculator lays every tile out the way you would set it, counts whole tiles and cut pieces, and shows the area method beside it so you can compare. Use it as a floor tile calculator, a wall tile calculator for showers and backsplashes, or a flooring calculator for any tiled floor. All of the math happens in your browser.

1. Pick the surface. Choose Floor or Wall or backsplash. Each keeps its own areas, tile and settings, so you can work out a bathroom floor and its shower walls side by side.
2. Enter the areas. Give each area its length and width (for a wall, its width and height), or choose Known area and type the square footage. Add a cut-out for anything you won't tile, such as a run of cabinets, a tub or a window, with its size and its distance from the left and from the bottom.
3. Choose the tile, joint and pattern. Pick a common size or enter the actual size from the box, the grout joint width, the tile thickness, the pattern and where the layout starts. Every length has its own unit, and you can type 8' 6", 3/16 or 600 mm.
4. Read the results. The results show the tiles to buy, the layout count, the area method, the area to tile and the boxes, with a drawing of the layout. Add the figures from your own products to see grout, thinset, trim pieces and cost, then copy the results, download them as a CSV file or print them.

Switch Units to Metric to see areas in square meters, grout in liters and new areas in meters. The calculator remembers your entries on this device.

How to measure for tile

Measure in whatever units you are comfortable with and write every figure down before you buy anything.

• Floors. Measure the length and width wall to wall, at the floor, and use the larger figure if the walls are not parallel. Split an L-shaped or T-shaped room into rectangles and enter each one as an area, or work out the total with the square footage calculator and enter it as a known area.
• Walls and showers. Measure each wall's width and the height you will tile: to the ceiling, to the top of a shower surround, or to the bottom of the upper cabinets for a backsplash. Enter each wall as its own area.
• Things you won't tile. Measure cabinets, an island, a tub or a window and where it sits, from the left edge and from the bottom of the area as the layout preview draws it. A cut-out is subtracted from the area, and the tiles around it are counted as cut.
• The tile. Tiles are sold by a nominal size, and the actual face can be a little smaller. Measure a tile or read the actual size on the box for the most precise layout.

How to calculate how many tiles you need

Counting tiles by hand takes five steps. The calculator does the same thing for every row of every area, in any pattern:

module        = tile + one grout joint, in each direction
whole tiles   = side ÷ module, rounded down, in each direction
edge piece    = side − whole tiles × module
tiles         = whole tiles + cut pieces (two pieces may share a tile)
tiles to buy  = tiles × (1 + extra ÷ 100), rounded up

1. Measure each area. Measure the length and width of the floor, or the width and height of each wall, and note anything you won't tile, such as cabinets, a tub or a window.
2. Note the tile and the joint. Read the actual tile size on the box and choose the grout joint width. One tile plus one joint is the space each tile takes up.
3. Lay out the rows. Divide each side by the tile plus one joint. The whole number is the count of whole tiles in that direction, and what is left over is the width of the cut pieces at the edge.
4. Count the cut pieces. Count a tile for every cut piece, but let two pieces share one tile when both fit in it, such as the end of one row and the start of the next.
5. Add the extra and round up. Add a percentage for breakage, mistakes and spares, round up to whole tiles, and then to whole boxes.

Example: a 12 × 10 ft floor, 12 × 12 in tiles and 1/8 in grout joints, laid in a straight grid from one corner. Each tile takes up 12.125 in. The 144 in length holds 11 whole tiles (133.375 in) and leaves a column of pieces 10 5/8 in wide; the 120 in width holds 9 whole rows and leaves a row 10 7/8 in wide. That makes 99 whole tiles and 21 cut pieces. No two cut pieces fit in one tile, so the layout takes 120 tiles, and with 5% extra you buy 126 tiles. That is the example the calculator opens with.

Layout count vs. area method

The quick method divides the area by the area one tile covers. For the example floor, 120 sq ft ÷ 1.0209 sq ft per tile and joint is about 117.5, so 118 tiles, and with the usual 10% waste 130. The layout count says 120 before any extra. Both are reasonable here, but they answer different questions: the area method guesses the cuts with a percentage, while the layout count finds them.

The difference grows with large tiles, small rooms and patterns with many cuts. Every cut piece at a wall needs a tile, and a big tile cut down to a narrow strip wastes most of itself. A percentage can't see that, so the calculator leads with the layout count and adds a smaller extra for breakage and spares. The area method stays in the results for comparison, and it is the only way to count a known area that has no shape to lay out.

Two things make the layout count a careful minimum, not a promise. It assumes each cut is made cleanly and that a matching offcut is used whenever one fits, and it ignores the width of the saw blade. If you are new to cutting tile, or the pattern has many angled cuts, raise the extra.

The diagonal layout has 38 cut pieces, but 14 of them come from the other half of a tile already cut: a square tile cut corner to corner gives two triangles, and each fits against a wall. That is why its layout count is close to the grid's.

Tile patterns and how much waste to allow

The pattern decides how many tiles reach an edge and at what angle they are cut. The calculator lays out six patterns:

• Straight (grid or stack bond). Tiles in straight rows and columns. Cuts happen only along the edges and around cut-outs.
• Offset ½ and offset ⅓ (running bond). Each row shifts by half or a third of a tile, like brickwork; the piece cut off the end of one row often starts the next.
• Diagonal (45°). The grid turned 45°, so every tile at a wall is cut at an angle.
• Herringbone. Rectangular tiles at right angles to each other in a zigzag, either at 45° to the walls or square to them. Herringbone needs tiles longer than they are wide.

No standards body publishes a waste allowance, so the area method's percentages in this calculator are starting points, not rules: 10% for straight and offset layouts, 15% for diagonal and 20% for herringbone. Change them to whatever your installer uses. The layout count doesn't use them at all.

For running bond with tiles longer than 18 in on the offset side, ANSI A108.02 says "the running bond offset will be a maximum of 33% unless otherwise specified by the tile manufacturer", as quoted by the Ceramic Tile Education Foundation. Long tiles are rarely perfectly flat, and a half offset puts the high middle of one tile next to the low ends of the next. The calculator warns you when a half offset meets a tile that long.

Where the layout starts matters too. Centered on the room instead of starting from a corner, the 45° herringbone takes 132 planks instead of 139. Try both under Start the layout; centering also keeps the cuts on opposite walls the same width.

Tile sizes, square feet per tile and boxes

The sizes in the calculator are common nominal sizes, not a standard list, and the tile you buy may measure a little less. Use the actual size on the box when you have it. The table shows how much one tile covers and how many tiles 100 square feet takes by the area method with 1/8 in joints.

Boxes. Enter the tiles per box, or the coverage per box if that is all the box gives, and the calculator rounds up to whole boxes. For the example floor with 10 tiles per box, the 126 tiles come to 13 boxes. Buy every box from the same production lot, because color and size can vary between lots, and keep a few spare tiles for repairs.

Grout joints and how much grout you need

ANSI A108.02 says "the actual grout joint size shall be at least three times the actual variation of facial dimensions of the tile supplied" and "in no circumstance shall the grout joint be less than 1/16”", as the Ceramic Tile Education Foundation quotes it. The tile maker's recommendation for your tile comes first; the calculator warns you below 1/16 in.

The grout fills the joints, so the amount follows from their size: joint length × joint width × joint depth. Every tile takes up its own area plus its share of the joint, so the joint is the share 1 − (tile area ÷ module area) of the floor. The depth is taken as the tile thickness, which is a little more than you will fill, because some thinset squeezes up into the joint.

For the example floor, the joints make up 2.05% of the 120 sq ft and run about 236 ft in all. At 1/8 in wide and 3/8 in deep, that is 132.9 in³ of grout, or 146.2 in³ (2.4 L) with a 10% margin for mixing and cleanup. To turn that into bags, enter the density and bag weight from the product data sheet, or the coverage from the chart on the bag; the calculator fills in no product figures, because grouts differ.

How much thinset (mortar) you need

How far a bag of thinset goes depends on the trowel notch, the size and back of the tile, and how flat the surface is, and the coverage printed on each bag is that product's own figure. There is no neutral table of trowel sizes and coverage to rely on, so the calculator asks for the coverage on your bag and divides: bags = area × (1 + margin ÷ 100) ÷ coverage per bag, rounded up.

Coverage on the bag is not the same as coverage under the tile. ANSI A108.5 requires that "the average uniform contact area shall be not less than 80% except on exterior or shower installations", "where the contact area shall be 95%", as quoted by the Ceramic Tile Education Foundation. Large tiles, uneven floors and showers can need a bigger notch or back-buttering to get there, which uses more thinset, so keep the margin or buy an extra bag.

Walls, backsplashes and showers

Choose Wall or backsplash and enter each wall as an area, width × height. A kitchen backsplash 10 ft wide and 18 in high, in 3 × 6 in subway tiles laid in an offset ½ pattern with 1/16 in joints, is 15 sq ft. The layout count is 121 tiles, 95 whole and 28 cut, and with 5% extra you buy 128 tiles. The area method with 10% waste happens to give 128 as well.

Windows, a tub or cabinets are cut-outs. An 8 × 8 ft wall with a 3 × 4 ft window, set 2 ft 6 in from the left and 3 ft above the floor, has 52 sq ft to tile. With 12 × 24 in tiles in an offset ⅓ pattern, only 8 tiles are whole and 27 are cut around the edges and the window, so the layout takes 29 tiles, more than the area method's 26 before waste. With large tiles on small walls, the cuts decide the count.

A shower usually has three walls and sometimes a ceiling, a niche or a bench. Enter each wall separately, enter the niche's back and sides as small areas of their own, and remember that tile on wet walls needs a waterproofing system behind it that follows the product's instructions.

Trim and bullnose pieces

Exposed edges, such as the top and ends of a backsplash, the edge of a wainscot or the outside corner of a shower, are finished with trim, bullnose tiles or a profile. Enter the length of edge to finish and the length of one piece, and the calculator rounds up to whole pieces, then adds the extra. The top and both ends of the 10 ft backsplash are 13 ft of edge: with 12 in pieces and 5% extra, that is 14 pieces. The results also show the total perimeter of your areas as a reminder, but only the exposed edges need trim.

Metric tiles and measurements

Switch Units to Metric to see square meters, liters and kilograms, and type lengths in meters, centimeters or millimeters. A room 4 m × 3 m is 12 m². With 60 × 60 cm tiles and 3 mm joints from one corner, it takes 24 whole tiles and 11 cut ones, 35 in all, or 37 with 5% extra. The grout for those joints is about 1.31 L at 10 mm deep, with a 10% margin.

The conversions are exact: since 1959, an inch is exactly 2.54 centimeters and a foot exactly 0.3048 meters, as the National Institute of Standards and Technology (NIST) lists in Handbook 44, Appendix C and Special Publication 811. So a square foot is exactly 0.09290304 square meters, and a pound exactly 0.45359237 kilograms.

Cutting tile safely

Ceramic and stone tiles make fine dust when they are cut dry. The U.S. Occupational Safety and Health Administration notes that crystalline silica "is also used to make products such as glass, pottery, ceramics, bricks, and artificial stone," and that respirable crystalline silica "is created when cutting, sawing, grinding, drilling, and crushing stone, rock, concrete, brick, block, and mortar." Read OSHA's page on crystalline silica before you cut. Wet cutting, a saw with water feed or dust collection, a respirator rated for the dust, eye and hearing protection, and cutting outdoors or with good ventilation all reduce what you breathe. Follow the instructions for your saw and the tile.

How we calculate

Every figure in the tool and on this page comes from the same code, and the examples above are checked against it automatically.

• Lengths. Every measurement is converted to feet first: inches ÷ 12, millimeters ÷ 304.8, centimeters ÷ 30.48, meters ÷ 0.3048, the exact NIST definitions.
• Layout. Each area is laid out as a lattice of tiles one module apart (tile + joint), turned 45° for diagonal and 45° herringbone, starting with a whole tile in the bottom-left corner or centered on the area. Every tile is clipped to the area and to its cut-outs: whole if nothing is cut, a cut piece if part of it shows, and not counted if none of it does.
• Offcuts. A piece cut by one straight line can share a tile with another piece cut at the same angle to the tile when their depths add up to no more than the tile, one from each end. Pieces are paired to use as few tiles as possible. Corner pieces, notches and pieces around cut-outs take a tile each. Saw kerf is ignored.
• Tiles to buy. (whole tiles + tiles for cut pieces) × (1 + extra ÷ 100), rounded up. A known area counts area × (1 + waste ÷ 100) ÷ module area, rounded up.
• Area method. Area to tile × (1 + waste ÷ 100) ÷ ((tile width + joint) × (tile length + joint)), rounded up.
• Grout. Area × (1 − tile area ÷ module area) × tile thickness × (1 + margin ÷ 100). Weight = volume × your density; bags = weight ÷ your bag weight, or area × (1 + margin ÷ 100) ÷ your coverage per bag, rounded up.
• Thinset. Area × (1 + margin ÷ 100) ÷ the coverage on your bag, rounded up.
• Trim. Length ÷ piece length, rounded up, then × (1 + extra ÷ 100), rounded up.
• Boxes and cost. Tiles ÷ tiles per box, or tiles × tile area ÷ coverage per box, rounded up. Cost uses only your prices, per tile, box, square foot or square meter. Nothing is filled in for you, because prices and products vary.

Your measurements stay on your device

The calculator runs entirely as JavaScript in your browser tab. Nothing you enter is uploaded: the page's Content-Security-Policy allows connections only back to this site, and the tool has no code that sends anything anywhere. It remembers your last entries in your browser's local storage, on your device only. There is no account and no cookie.

Sources

• National Institute of Standards and Technology: NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement: 1 foot = 12 inches = 0.3048 meter, 1 inch = 2.54 centimeters, and 1 pound = 0.45359237 kilogram, exactly.
• NIST Special Publication 811, Appendix B.9, Factors for units listed by kind of quantity: exact factors for the foot, the inch and the pound.
• Ceramic Tile Education Foundation: ANSI Standards, a Tile Installer's Best Friend, quoting ANSI A108.02 on grout joint size and the running bond offset.
• Ceramic Tile Education Foundation: Insufficient Mortar, quoting ANSI A108.5 on mortar contact.
• U.S. Occupational Safety and Health Administration: Silica, Crystalline, on where respirable crystalline silica comes from.

Reviewed by microplugins · Last updated October 2026

This is an educational tool, not professional tiling or construction advice. Tile sizes, coverage and installation requirements vary: check the actual size on the box, the instructions for each product and your local building code, and buy every box from the same lot.