Tile calculator: how much tile do I need?
Counts the grout line and rounds up to whole boxes. Free, no sign-up, nothing leaves your browser.
Worked example: bathroom floorExample numbers
4 boxes
32 tiles for 58.25 sq ft
Type a surface and your tile size, or try an example.
Bathroom floor: 9.5 ft x 8 ft = 76.00 sq ft
Less Tub: 5 ft x 2.5 ft = 12.50 sq ft
Less Vanity: 3 ft x 1.75 ft = 5.25 sq ft
Net: 76.00 - 12.50 - 5.25 = 58.25 sq ft
Area to tile: 58.25 sq ft
Each tile with its grout line: 12 1/8 x 24 1/8 in = 2.0314 sq ft
58.25 sq ft / 2.0314 sq ft = 28.68 tiles' worth
28.68 x 1.1 for 10% extra = 31.548, rounded up: 32 tiles
32 tiles / 8 per box, rounded up: 4 boxes (32 tiles)
Past your plan of 32: 0 tiles
Over the 29 that cover the area with no extra: 3 tiles
Solid: the area itself. Striped: your extra. Empty: what rounding up adds.
No tile size typed, so this counts by area and sq ft per box. Grout lines and pieces don't count here.
Lines show rounded figures. The calculator works from exact values, rounds each figure once, and counts from the figure on the line above.
Still needed
The order shows once every surface you started is finished, with a tile size or the sq ft per box.
Clear every surface, the tile and the box figures?
Your browser blocked copying. Select the text below and copy it.
Measure twice, use the size printed on the box, and confirm the order with your installer.
How the tile calculator works
You type each surface the way the tape gave it to you, and the calculator shows how it read every length, right under the field. A floor is length times width, a wall is width times height. Then you take out what won't be tiled, and each piece comes off the surface it sits in: the tub off the floor, the window off its own wall.
Next comes the grout line. A tile goes down as a little more than itself, the tile plus one grout line along two of its sides. A 12 by 24 in tile with a 1/8 in line covers 12 1/8 by 24 1/8 in of floor, so your area is divided by that, not by the tile alone. On large tile it can change nothing at all: 24 by 24 in tile with a 1/16 in line comes to 25 tiles on 100 square feet either way. On 4 in tile with a 1/4 in line it saves about one tile in nine.
Your extra goes on top, and the count rounds up to whole tiles. Then up again to whole boxes, because nobody sells a third of a box. A line under the box count tells you how far your extra could go before the order needs another box. In our bathroom example, four boxes cover any extra from zero to 11.5%, so agonizing between 8% and 11% changes nothing you'll carry out of the store.
The calculator works every figure in exact fractions and rounds it once, for reading. Each count comes from the figure printed on the line above it, so a line and its count never argue.
Who this is for
You're tiling a bathroom floor, a tub surround or a kitchen backsplash, or paying someone who is. You've got a tape, a product page that says something like "8 pieces per carton", and one question: how many boxes?
If your installer says to buy five boxes, type the room and the box and see what five boxes hold against what the floor needs. That gives you a fair question to bring back to them, and they may well have a good answer.
The count stops at tile and boxes. Grout, thinset, backer board and trim pieces are separate buys, and an odd-shaped room is easier on our square footage calculator first.
Homeowner questions about tile
How many tiles do I need for 100 square feet?
For 12 by 24 in tile with a 1/8 in grout line, 100 square feet comes to 49.23 tiles' worth: 50 tiles with no extra, 55 with 10%. Smaller tile swings it further, and the grout line matters more. Four-inch tile with a 1/4 in line needs 798 tiles, not the 900 you'd get dividing by the tile alone.
How much extra tile should I buy?
There's no single right number. We looked for a manufacturer or a standard that sets one per layout and came up empty. Cuts drive it: a straight layout cuts tiles along the edges, while a diagonal or a herringbone cuts at every edge, so ask your installer for their figure. Type it in, and the calculator shows how far it can stretch before you'd need another box.
Do you count grout lines when you figure tile?
You should, and the calculator does. Each tile covers its own size plus a grout line, so dividing by the tile alone overcounts. How much depends on size: 12 by 12 in tile with a 1/8 in line drops from 100 tiles to 98 on 100 square feet, while 24 by 24 in tile with a 1/16 in line stays at 25. When the line changes nothing, you won't see a word about it.
What is the actual size of a 12x24 tile?
Go by the carton, because the name on the shelf can be rounded. MAPEI's grout data sheet lists 12 by 24 in beside 300 by 600 mm, which is 11.81 by 23.62 in. One Daltile 12 by 24 we looked up at a retailer lists 11.75 by 23.62 in. In our bathroom example that's a whole box: typing a true 12 by 24 gives 4 boxes, and typing 300 by 600 mm gives 5.
How many square feet are in a box of tile?
Whatever the carton says, and it's worth checking against the tile. Eight true 12 by 24 in tiles cover exactly 16 square feet, while eight 300 by 600 mm tiles cover about 15.5. Type the pieces, the square feet and the tile size, and the calculator tells you when the box fits a smaller or a larger tile than the one you typed.
How much tile do I need for a tub surround?
Treat each wall as its own surface: the back wall and the two ends, from the tub rim to where the tile stops. A 5 ft back wall and two 2 1/2 ft ends, all 6 ft high, less a 2 by 2 1/2 ft window, is 55 square feet. In 3 by 6 in subway tile with a 1/16 in line and 10% extra, that's 470 tiles. The waterproofing behind the tile is a job for a pro.
How do I measure for a kitchen backsplash?
Measure each run of wall along the counter, and its height from the counter to the cabinets. Each run is its own surface, and a window that dips into the strip comes out as a leave-out. Outlets stay in, because the tile gets cut around them anyway. A 9 1/2 ft run less a 3 by 1 ft window, plus a 6 ft run, both 18 in high, is 20.25 square feet.
How wide should the grout line be?
Your installer picks it from the tile's size variation and the maker's instructions. Marazzi's older layout brochure quotes three times the variation and a 1/16 inch floor. Its current FAQ asks for at least 1/8 inch on rectified tile larger than 15 inches. A general floor isn't a recommendation for your tile. Type the joint your installer will use, and the count follows it.
What is attic stock, and should I keep extra tile?
Attic stock is spare tile you keep for repairs. Daltile "highly recommend[s]" buying about 10% more tile than you expect to need and keeping it, so a cracked tile can be replaced from "the same dye lot and printing process" as the rest. A box bought years later may not match. Whether that 10% sits on top of your cutting allowance is your call. The calculator adds the one figure you type.
Does this tell me how much grout to buy?
No. Grout coverage depends on the product. MAPEI's US data sheet for one of its grouts prints its own chart by tile size, thickness and joint width, "for estimating purposes only." Find your row on the bag you're buying.
How to calculate how much tile you need
Sketch the room, then split it into rectangles you can measure. Floors take length and width, walls take width and height. Write feet and inches the way the tape shows them.
Take out what won't be tiled: the tub, the vanity, cabinets, a window. Add up what's left, and that's your area.
Find the tile's real size on the carton and add one grout line to its length and one to its width. Divide the area by that, add your extra, and round up to whole tiles. Then divide by the pieces in a box and round up again. Two roundings, both up, in that order. Add the extra after rounding to boxes and you're padding a number that's already padded.
Laminate and vinyl plank flooring by the carton
Laminate and vinyl plank come in cartons marked with the square feet they cover, and there's no grout line to count. Leave the tile size empty, open What the box says, and type the sq ft per box. The calculator adds your extra to the area and rounds up to whole cartons.
A 12 1/2 by 11 1/4 ft bedroom with a 5 by 2 1/2 ft closet is 153.13 square feet. At 10% extra and 22.5 sq ft per carton, that's 8 cartons, and 8 cartons cover any extra up to 17.5%.
Carpet is a different sum, and we don't count it here. It comes off a roll of fixed width, so the seams and the drops decide the order, not the square feet.
Sources and last checked
- Units: NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement. 12 in = 1 ft; 1 sq ft = 144 sq in; 1 in = 2.54 cm exactly, which is 25.4 mm.
- Grout joint size: Marazzi USA's older pattern layout brochure, quoting ANSI A108.02, section 4.3.8; current Marazzi FAQ for rectified tile larger than 15 inches. As of October 8, 2026 we haven't read the current ANSI edition, dated July 2026. It's sold, and we can't promise it still says the same.
- Attic stock: Daltile, Tile and Natural Stone FAQs.
- 12 x 24 in beside 300 x 600 mm, and grout coverage: MAPEI Ultracolor Plus FA technical data sheet (US), edition date August 28, 2026.
- One 12 x 24 tile's listed size: a retailer's product page for Daltile Median, checked against Daltile's own Median sales sheet.
Last checked: October 8, 2026 (unit constants and reference lines version 2026-10-07).
More free tools for your project
- All free tools on Industry Oversight
Every free tool we've built, in one list.
- Square footage calculator: rooms, L-shapes, circles and triangles
For a room that isn't a rectangle. Work out the total there, then type it here as square feet.
- Paint calculator: gallons and quarts for walls and ceilings
The other half of a bathroom or kitchen redo.
Having it installed? Find a tile installer near you.