What Is a Tile Calculator?
A tile calculator is an online estimating tool that converts room dimensions, tile size, grout joint width, and a waste percentage into the number of tiles and boxes to buy.
A plain area calculator stops at square footage. This one keeps going until you have an order quantity.
Most versions return some mix of these outputs:
- Total area in square feet or square meters
- Tile count, including waste
- Boxes to order, rounded up
- Material cost, once you enter a price
- Grout and thinset quantities, on the better tools
Scale check: a 10 ft by 12 ft floor is 120 sq ft, which takes 120 tiles of 12 inches square. Add 10% waste and the order becomes 132 tiles.
The tool does not plan your layout or check that the subfloor is flat. It counts material, nothing more.
How to Use This Tile Calculator
The calculator above covers all five outputs, grout and thinset included. Results update as you type.
- Measure each section. Switch between floor and wall, then add as many rectangles as the space needs.
- Subtract what stays bare. Quick-add a door, window, bathtub or kitchen island and adjust its size.
- Pick your tile and joint. Enter the tile thickness too, because grout depends on joint depth.
- Choose a layout. Waste fills in at 10% for straight and brick, 15% for diagonal and 20% for herringbone. Move the slider if your installer or supplier recommends a different figure.
- Add the carton details. Enter tiles per box or the coverage printed on the label, plus the price.
When you are done, copy the estimate, share it as a link, or print it for the store.
How to Measure a Room for a Tile Calculator
Measure the length and width of every rectangle you plan to tile, multiply each pair to get its area, add the areas together, and subtract any openings. Use one unit throughout.
The tool then asks for five inputs:
- Room size: length and width, or wall width and height
- Tile size: the nominal dimensions printed on the carton
- Joint width: the grout line, in fractions of an inch or in millimeters
- Waste: a percentage added on top
- Units: feet, inches, meters, centimeters, or millimeters
Mixed units are the easiest way to get a wrong answer. Square inches divide by 144 to reach square feet, so a 12 by 18 inch tile (216 square inches) covers 1.5 sq ft.
Floors
Floor area is length times width.
L-shaped and notched rooms get split into rectangles. Calculate each one, then add the results, which is the method Hunker's tile guide describes.
- Take each dimension at its widest point, since rooms are rarely perfectly square
- Measure twice before typing anything in
Walls
Per wall: width times height, calculated on its own.
Total: add every wall together.
Partial height: if the tile stops at a set line, as on a tub surround or wainscot, use that height instead of floor to ceiling.
Openings and obstacles
Toolstation's calculator guidance subtracts each door or window by multiplying its width by its height and taking that from the total area.
Keep the waste percentage on top of the reduced area. Cuts around those same openings are where a large share of waste comes from.
Small vents and switch plates are not worth subtracting.
The Formula Behind a Tile Calculator
A tile calculator divides the area to be tiled by the area of one tile, multiplies by one plus the waste percentage, and rounds up to a whole tile.
- Multiply length by width for each surface, then add the areas
- Multiply tile length by tile width, in the same unit as the room
- Divide the surface area by the tile area
- Multiply the result by 1.10 for 10% waste (1.15 for 15%, and so on)
- Round up to the next whole tile
Omni Calculator states the core relationship as number of tiles equals the area to tile divided by the area of one tile. Every other step adjusts that quotient.
Round once, at the end. Rounding the count up before adding waste can push the order one tile higher than needed.
Worked metric example: a 12 m² floor with 300 by 300 mm tiles (0.09 m² each) needs 133.3 tiles. Add 10% and you get 146.7, so the order is 147 tiles.
Joint width: a calculator that accepts one divides by the tile size plus the joint, so a 12 inch tile on a 1/8 inch line covers 12.125 by 12.125 inches.
The effect is small on large tile and big on mosaics. By arithmetic, that 12 inch tile needs about 2% fewer pieces than the nominal count, while a 2 inch mosaic tile on the same joint needs about 11% fewer.
GigaCalculator includes a gap size field for this. A divider that ignores the joint overcounts slightly on small tile, which errs toward having enough.
How Much Waste Should You Add to a Tile Order?
Start at 10% for a straight lay on standard tile. Published guidance then spreads from 5% at the low end to 35% for complex large-format layouts.
| Source | What drives the figure | Overage |
|---|---|---|
| Hunker | Installer experience and room shape | 5% professional, 10% DIY, 15% irregular rooms |
| Bob Vila | Flat minimum for cuts, breakage, repairs | 10% |
| TileBar | Flat figure that includes future repairs | 15% |
| Artistic Tile | Tile format and layout | 20% standard, 25% to 30% diagonal, 30% to 35% large format |
Figures reflect each publisher's page as of October 2026.
Part of the gap is scope. TileBar's 15% covers cuts and future repairs, while Hunker ties its number to who does the cutting.
Artistic Tile ties its number to tile format, which is why it runs highest. Each figure is a recommendation, and none of these pages cites waste measured on completed jobs.
For standard tile in a plain rectangular room, 10% to 15% is a sound range. The 30% figures belong to large-format and complex layouts.
Layout pattern
Waste follows the number of cut tiles, and the layout decides that number.
- Straight lay: cuts only along the edges
- Brick offset: a cut at the end of every row, though the offcut often fits the next row
- Diagonal: nearly every perimeter tile is cut at an angle, and the offcuts rarely get reused
- Herringbone: angled cuts at both ends of each run
Artistic Tile sets herringbone at 20% to 25%. It also suggests tile whose length divides evenly by its width, such as 2 by 6 or 3 by 6 inch, to cut fewer pieces.
Tile size and material
ANSI's 2023 terminology standard (A108.T), introduced with the January 2024 ANSI A108, A118, A136 specifications, defines large format tile as a facial dimension greater than 23 inches, according to FLOOR Tile in August 2024.
That is not the only line in use. ANSI A108.02 applies its tighter substrate flatness rule from 15 inches, and Artistic Tile starts its 30% large-format minimum at 18 by 36 inches.
So a 20 inch square tile triggers the 15 inch flatness rule, sits below ANSI's 23 inch definition, and falls short of Artistic Tile's 18 by 36 line. Ask your supplier which definition its overage advice uses.
- Small format (4 to 9 inch edge): Artistic Tile's minimum is 20%
- Natural stone: color and veining vary within one lot, and TileBar's product notes recommend blending boxes, so budget for matching as well as cutting
A failed cut on a large tile loses a bigger piece than the same mistake on a small one.
Converting Tile Count Into Boxes and Cost
Divide the total area including waste by the coverage printed on the carton, then round up to whole boxes. A fractional box does not exist at the checkout.
For a 120 sq ft room with 10% waste, the order is 132 sq ft. A carton covering 15 sq ft gives 8.8, so you buy 9 boxes, which is 135 sq ft.
Work from the carton figure, not from tile size alone. Rounding up to a full box also adds a small buffer on top of the waste percentage.
Cost is boxes times price per box, or total square feet times price per square foot. Omni Calculator takes a price per tile and runs it through the count.
At an illustrative $4.50 per sq ft, 135 sq ft of tile costs $607.50. That figure covers tile only, so setting materials and labor come on top, and a home renovation cost calculator is the better tool for setting tile beside labor and demolition in one budget.
Tile sold by the piece skips the box step, so round up the tile count instead. Flooring sold by the carton, such as planks, follows the same box math, which a flooring calculator handles.
Order every box at once so the lot numbers match, then mix cartons while setting. TileBar recommends blending boxes before and during installation.
Over-ordering is not free. TileBar accepts returns within 180 days but charges a 15% restocking fee.
How Much Grout and Thinset Does a Tile Project Need?
Grout and thinset are sold by weight, and each follows its own coverage rule. Grout depends on tile size, joint width, and tile thickness, while thinset depends on trowel notch size.
Take coverage from the maker's chart for the exact product, then round up to whole bags.
Grout
Joint volume drives the quantity.
Per square foot, grout volume is joint length times joint width times tile thickness. A 12 inch tile that is 3/8 inch thick on a 1/8 inch joint has 24 inches of joint per square foot, or 1.125 cubic inches of grout.
A 1 inch mosaic that is 1/4 inch thick has 288 inches of joint per square foot and needs 9 cubic inches. That is eight times more.
CUSTOM Building Products' data sheet for its non-sanded grout (copyright 2026) shows the same pattern per 25 lb bag:
| Tile size and thickness | 1/8 inch joint | 1/16 inch joint |
|---|---|---|
| 1 by 1 by 1/4 inch | 50 sq ft | 110 sq ft |
| 6 by 6 by 1/4 inch | 300 sq ft | 625 sq ft |
| 12 by 12 by 3/8 inch | 427 sq ft | 827 sq ft |
Narrowing the joint from 1/8 to 1/16 inch roughly doubles coverage. Sanded products publish their own charts, so look up the exact grout you plan to buy.
Grout type: CUSTOM rates the non-sanded product for joints up to 1/8 inch and says it will not scratch glazed tile or polished marble. Wider joints take sanded grout.
Calculate grout on the installed area, not on the order that includes waste, since offcuts never get grouted. Then add a margin: Mapei recommends 5% to 10% overage on its product calculator pages, as of October 2026.
Web grout calculators agree on the formula but not on the density constant, so one tile and joint can return very different bag counts. The manufacturer's chart settles it.
Thinset
CUSTOM Building Products' data sheets for VersaBond Flex, MultiSet, and CustomBlend list identical bag coverage: 85 to 95 sq ft per 50 lb bag with a 1/4 by 1/4 by 1/4 inch square-notch trowel, and 60 to 67 sq ft with a 1/4 by 3/8 by 1/4 inch notch.
Coverage follows the notch, not the brand. A deeper notch leaves taller ridges, so each bag spreads over less floor.
Bags needed: installed area divided by coverage per bag at your notch, rounded up.
Safe input: use the low end of the range. A 120 sq ft floor at 60 sq ft per bag lands on exactly 2 bags with no margin, so buy 3.
Floors, Walls, Backsplashes and Showers: What Changes in the Calculation
Surface type changes the area method, the cutouts, and the thinset estimate. The core formula stays the same.
- Floors: one or two large rectangles with doorways at the edges, so the formula applies as is
- Walls: each wall is its own rectangle, and trim or bullnose pieces get a separate count from the field tile
- Backsplashes: a short, wide strip split into sections wherever the height changes, with windows and outlets cut out
- Showers: three walls, a curb, a floor, and any niche or bench, each measured on its own
Mercury Mosaics' measuring guide treats a backsplash that rises higher above the stove than above the counters as separate sections, and it subtracts any no-tile areas such as windows.
In a shower, the curb has two edges that need trim, and a niche set in a different tile gets its own count, according to DIY Tile Guy.
The mortar rule is the part calculators skip. ANSI A108.5 sets minimum contact area at 80% for dry interior installations and 95% for exteriors and wet interior areas, as quoted in a December 2024 CTEF Tile Tip in Floor Trends.
The Ceramic Tile Foundation adds that natural stone needs 95% in every location. Plan on the low end of the thinset bag range for showers and for stone.
Showers also carry the most layout decisions. Settling niche and bench positions from shower design ideas before you measure keeps the section list from changing mid-order.
Which Online Tile Calculator Should You Use?
Choose one tool for the tile count that takes joint width, waste, and box coverage, then run grout and mortar through the maker's own calculator.
| Tool | Handles | Leaves to you |
|---|---|---|
| GigaCalculator | Gap size, waste percentage, boxes, cost from price per box | Non-rectangular tile shapes |
| Omni Calculator | Tile count, boxes, cost from price per tile | Joint width (its explainer divides area by tile area, with no joint term) |
| Inch Calculator | Floor, wall and backsplash modes, box coverage entry, cost, thinset and grout guidance | Mixed tile sizes, which it calculates as separate runs |
| Toolstation | Metric tile and room sizes, several walls or floors | Waste allowance, which the page tells you to add by hand |
- Small tile or wide joints: pick a tool with a gap field, since the joint moves the count most there
- Tile already chosen: use the retailer's product-page calculator, which works from that tile's carton coverage (Mineral Tiles puts one on every product page)
- Grout and mortar: use the manufacturer's tool for the product you will buy
Mapei's grout calculator takes tile format, joint width, and surface area, then returns quantities by pack size. CUSTOM points users to its Material Calculator for trowel sizes missing from a data sheet.
A general tile tool's grout figure is a rough check at best. When it disagrees with the maker's chart, the chart wins.
When a Tile Calculator Gives the Wrong Number
A tile calculator gives the wrong number when the surface is not a clean rectangle, when the layout breaks its joint math, or when the setting material depends on how the tile is installed instead of how big it is.
- Irregular rooms: angled walls and curves need triangle areas (half base times height) or a paper template, split out before anything is typed in
- Herringbone and basketweave: joint lengths vary, and Calculover's grout tool states that its formula assumes a rectangular grid with uniform joints
- Mosaic sheets: the same grid assumption applies, so hand-adjust the grout figure
- Mixed tile in one project: field, border, and accent tiles each need their own run, as Inch Calculator notes for different sizes and patterns
Large tile breaks thinset estimates in a different way. CUSTOM's data sheets say larger tiles, deep back patterns, and ungauged natural stone can need bigger notches and flat back-troweling.
For back-troweled tile, CUSTOM tells installers to estimate the extra mortar from the underside pattern and depth, and to test coverage before committing.
A calculator multiplies what you typed. Anything it has no field for, you add by hand.
Tile Calculator FAQ
How do I count bullnose and trim pieces?
Measure the linear feet of exposed edge, divide by the length of one trim piece, and round up. Take that edge strip out of the field tile area so you are not buying the same ground twice.
Add waste to the trim count too.
Should I keep spare tile after the job?
Yes. Set aside at least one unopened carton from the same lot.
Production runs vary and designs get discontinued, so a repair tile bought later may never match.
Can a tile calculator handle hexagon tiles and mosaic sheets?
Only partly. Many tools assume rectangular tiles, and GigaCalculator tells users to do the math themselves for other shapes.
For a hexagon, work out one tile's area as roughly 2.598 times the side length squared. For mosaic sheets, enter the square footage printed per sheet in place of a single-tile size.
How accurate is a tile calculator?
The division is exact. The result is only as reliable as your measurements, the tile size you enter, and the waste percentage you pick.
Setting materials are looser still, since Mapei describes its own grout output as indicative.
Ready to run your own numbers? Jump back to the tile calculator.