Calculators · Tile Calculator
Walls & finishesTile Calculator
Add the floor or wall areas, pick the tile size and grout joint, and get the number of tiles, boxes and grout.
Tiles needed
—
How to calculate how many tiles you need
A tile calculator answers one question: how many tiles cover this surface. It does it in five steps, and you can read each one in the result above. The same steps work for a floor, a wall, a shower or a backsplash.
- Area. Multiply length by width in feet. For an L-shaped or odd room, add one area for each rectangle. To leave out a window, a tub or a built-in, subtract its size from the area before you type it, using “Area I already know”.
- Space one tile takes. Add the grout joint to the width and to the length, multiply them and divide by 144 to get square feet. A 12 by 12 inch tile with a 1/8 inch joint takes (12.125 × 12.125) ÷ 144 = 1.0209 square feet.
- Tiles. Divide the area by the space one tile takes.
- Waste. Multiply by 1 plus your waste. With 10% waste, multiply by 1.10. Round up, because you cannot buy part of a tile.
- Boxes. Divide by the tiles in a box, or turn the tiles back into square feet and divide by the square feet in a box. Round up again.
Why the grout joint changes the count
The usual shortcut is to divide the area by the area of one tile. It ignores the joints, so it never counts fewer tiles than the floor needs, and with small tiles it counts noticeably more. Here is a 10 ft by 12 ft floor, 120 square feet, with 12 by 12 inch tiles and no waste.
| Grout joint | Space per tile | Tiles |
|---|---|---|
| None (the shortcut) | 1.0000 sq ft | 120 |
| 1/16 in | 1.0104 sq ft | 119 |
| 1/8 in | 1.0209 sq ft | 118 |
| 3/16 in | 1.0315 sq ft | 117 |
| 1/4 in | 1.0421 sq ft | 116 |
The smaller the tile, the more the joints matter. This table covers 100 square feet with a 1/8 inch joint and no waste.
| Tile size | Shortcut | With the joint |
|---|---|---|
| 2 × 2 in | 3,600 | 3,189 |
| 6 × 24 in | 100 | 98 |
| 12 × 12 in | 100 | 98 |
| 12 × 24 in | 50 | 50 |
| 24 × 24 in | 25 | 25 |
With big tiles the two methods often land on the same number once you round up. This is an area calculation, so it cannot count the part tiles at the edges of the room. That is what the waste box is for.
Example: a 10 ft by 12 ft floor
| Step | 12 × 12 in tile, 1/8 in joint | 24 × 24 in tile, 1/8 in joint, 10% waste |
|---|---|---|
| Area | 10 × 12 = 120 sq ft | 10 × 12 = 120 sq ft |
| Space per tile | 12.125 × 12.125 ÷ 144 = 1.0209 sq ft | 24.125 × 24.125 ÷ 144 = 4.0418 sq ft |
| Tiles | 120 ÷ 1.0209 = 117.54 | 120 ÷ 4.0418 = 29.69 |
| With waste | none | 29.69 × 1.10 = 32.66 |
| Rounded up | 118 tiles | 33 tiles |
With 10% waste the 12 by 12 inch floor needs 130 tiles. If a box holds 10 tiles, that is 13 boxes.
How wide should the grout joint be?
The joint is not only a look. It lets the installer keep the lines straight when tiles are not all exactly the same size. The installation standard ANSI A108.02, section 4.3.8, as quoted by the Ceramic Tile Education Foundation (checked October 2026), sets these rules:
- Never less than 1/16 inch. That is the floor, not a target.
- At least three times the variation in the face size of the tile. The standard’s own example is a variation of 1/16 inch, which calls for a joint of at least 3/16 inch.
- Tiles with a side over 15 inches, set in a running bond (brick) pattern: an average of at least 1/8 inch for rectified tiles and 3/16 inch for calibrated (non-rectified) tiles, plus the warpage of the longest edge.
Custom Building Products’ bulletin TB87 repeats the same rules and says the Tile Council of North America recommends 1/8 inch for rectified tile and 3/16 inch for calibrated tile. A TileLetter article (a tile installation magazine, 2019) adds that a 1/16 inch joint is not suitable for every job just because the standard allows it, and gives a general guide of about 3/16 inch for pressed ceramic and porcelain and about 1/8 inch for rectified tile. It also says the tile maker’s instructions always come before a generic guideline. Type the joint your tile maker gives you.
How much extra tile to buy
There is no single number. The sources we opened give different ones, and none of them is a standard. That is why the waste box starts empty and the choice is yours.
| Source | What it says |
|---|---|
| Clé Tile (tile seller) | 10%. 15% for intricate patterns or diagonal layouts. 15% to 20% for complex room shapes. Up to 25% for diagonal. |
| Mr. Handyman (home repair) | 10% to 20% more than the math gives. |
| Homedit (home design site) | 10%. 20% for herringbone or angled patterns. |
| Fireclay Tile (handmade tile maker) | At least 15% to 20%. About 5% can be enough on a large commercial job. |
All of them were read in October 2026. Clé Tile says larger tiles may result in less waste overall because fewer cuts are typically required, but that when a cut is needed you might lose a larger portion of material. Diagonal and herringbone layouts and complex room shapes get higher figures in the table above. If you are unsure, ask the maker or the store that sells your tile.
Boxes and spare tiles
Boxes can be listed in square feet or in tiles. Pick the one your box shows and type it in. When you give tiles per box, the calculator tells you how many tiles you will have left over. When you give square feet per box, it turns the tiles back into square feet first and then rounds up to whole boxes.
Grout estimate
The grout figure comes from the data sheet of Mapei Ultracolor Plus FA (checked October 2026). It lists how many square feet a 10 pound bag covers for each tile size and joint width, for joints from 1/16 to 3/4 inch, and it comes in 10 and 25 pound bags. The sheet does not give a formula, so we worked one out from its table. Every cell follows the same geometry: the length of joint per square foot, times the joint width, times the tile thickness, times about 0.0573 pounds of grout per cubic inch of joint. The sheet’s table assumes tiles 3/8 inch thick, and 1/4 inch for the 2 by 2 inch tile. The calculator matches all 40 cells of the 10 pound table within 0.7% for joints up to 3/16 inch and within 8% for wider ones, where the table rounds up.
| Tile, 3/8 in thick | Joint | Mapei table, sq ft per 10 lb | This calculator |
|---|---|---|---|
| 12 × 12 in | 1/8 in | 156 | 155 |
| 12 × 12 in | 1/4 in | 78 | 78 |
| 12 × 24 in | 1/8 in | 207 | 207 |
| 24 × 24 in | 1/8 in | 311 | 310 |
This is an estimate for one product. Other grouts weigh and spread differently, so use it as a starting point and check the coverage on the label of the grout you buy. The grout is worked out on the area without waste, because broken tiles do not get grouted. It does not add anything for grout lost while you work.
What this tool does not cover
- Thin-set and other adhesive. How far a bag goes depends on the trowel, the tile and the surface, so it is not estimated here. Read the coverage on the bag.
- Layout. It counts from the area. It does not plan where the cuts fall or which pattern you lay.
- Price. No prices are shown, because they change by store and region. Take your numbers to your supplier and ask for a quote.
Frequently asked questions
How many tiles do I need for a room?
Multiply the length by the width in feet to get the area. Then work out how much floor one tile covers, including its share of the grout joint: (width + joint) × (length + joint) ÷ 144, with the sizes in inches. Divide the area by that number, add your waste and round up. For a 10 ft by 12 ft room with 12 inch tiles and a 1/8 inch joint, 120 ÷ 1.0209 = 117.5, so 118 tiles before waste.
How many 12x12 tiles for a 10x12 room?
The room is 120 square feet and a 12 by 12 inch tile covers 1 square foot, so the quick answer is 120 tiles. Once you count a 1/8 inch grout joint, each tile takes 1.0209 square feet and the count drops to 118. With 10% waste it is 130 tiles, where the quick method gives 132.
How many 12x24 tiles do I need?
A 12 by 24 inch tile covers 2 square feet, so you need about half as many tiles as square feet. For 100 square feet that is 50 tiles. With a 1/8 inch joint the exact figure is 49.2, which also rounds up to 50. Adding 10% waste gives 55 tiles. Enter your own area above to get your number.
How much extra tile should I buy?
Sources disagree, so the waste box is yours to fill in. Clé Tile says 10%, and 15% for intricate or diagonal layouts. Mr. Handyman says 10% to 20%. Homedit says 10%, or 20% for herringbone and angled patterns. Fireclay Tile, a maker of handmade tile, asks for at least 15% to 20%, and says about 5% can be enough on large commercial jobs. Leave the box empty and the calculator adds nothing.
How wide should the grout joint be?
ANSI A108.02 says a grout joint must never be less than 1/16 inch, and at least three times the variation in the face size of the tile. For tiles with a side over 15 inches set in a running bond pattern, it asks for an average of at least 1/8 inch for rectified tiles and 3/16 inch for non-rectified tiles. The tile maker's instructions come first, so type the joint they give you.
Does the tile count include the grout joint?
Yes. Each tile is counted together with its share of the joint, so the result is a little lower than the quick method of area divided by tile size. The gap is small for large tiles and bigger for small ones. For 100 square feet of 2 by 2 inch tiles with a 1/8 inch joint, the quick method says 3,600 tiles and this calculator says 3,189.
How much grout do I need?
It depends on the joint width, the tile size and the tile thickness. The calculator estimates it for one product, Mapei Ultracolor Plus FA, from the coverage table in its data sheet. For 120 square feet of 12 by 12 inch tile, 3/8 inch thick, with a 1/8 inch joint, that is about 7.7 pounds, so one 10 pound bag. Other grouts can differ, so check the label of the one you buy.
More calculators
- Square Footage Calculator Add rooms, circles or triangles and get the total in sq ft, sq yd, m² and acres.
- Paver Calculator Estimate the pavers, base gravel and bedding sand for a patio or walkway.
- Drywall Calculator Calculate the drywall sheets for walls and ceilings, with or without subtracting doors and windows, plus tape, screws and compound.