Tile calculator
Find how many tiles and boxes to buy for a floor or wall, with the grout joint, a waste allowance for your layout and the grout you need.
Sizes are nominal. For the closest count, type the actual size from the box.
The spacer size you will use.
Tiles and boxes
- Tiles to buy
- 6560 tiles cover the area, plus 5 for 10% waste
- Boxes
- 972 tiles at 8 per box
- Area to tile
- 120 sq ftEach tile with its joint takes up 2.03 sq ft
Grout joint check
- MetRectified tile: at least 1/8 in
Minimums from the TCNA Handbook. Your tile maker’s instructions come first.
Box size and waste
Printed on the box. The starting figure is only a placeholder.
Extra for cuts and breakage. It changes with the layout; edit it to match your installer.
Grout
On the box or the tile maker’s data sheet.
Grout density and extra
From the grout data sheet. kg/L, kg/dm³ and specific gravity are the same number.
Grout makers suggest adding 10% or more.
- Grout to buy
- 7.04 lb0.053 lb/sq ft, plus 10% for mixing and cleanup
- Bags
- 1 × 25 lb
Estimate only. Check product labels and local building rules before you buy or build.
Quick answer
Divide the area by the space one tile takes up with its grout joint, add a waste allowance and round up. A 12 × 10 ft floor is 120 sq ft, and a 12 × 24 in tile with a 1/8 in joint takes up 12.125 × 24.125 in, or 2.03 sq ft, so 59.1 tiles cover the floor. With 10% extra for cuts you buy 65 tiles.
How to use the tile calculator
- Choose Room size and enter the length and width in feet. For an L-shaped room, split it into rectangles and add each one as another area. If you already know the square footage, choose Total area.
- Pick a tile size from the list, or choose Other size and type the actual size printed on the box. Then pick the grout joint and the layout.
- Open Box size and waste to enter the pieces or square feet per box from the label. The waste allowance follows the layout; change it if your installer uses a different figure.
- For grout, choose the tile thickness and the bag size. If your grout’s data sheet gives a density, enter it under Grout density and extra.
How do you calculate how many tiles you need?
Each tile takes up its own size plus one joint width in each direction, so a 12 × 24 in tile with a 1/8 in joint fills a 12.125 × 24.125 in patch of floor. Divide the area by that patch, add a waste allowance for cuts and breakage, and round up to whole tiles and then to whole boxes.
Grout fills the joints, so the amount depends on how much joint there is per square foot and how deep it is. Grout makers print the formula below on their data sheets, with the joint depth equal to the tile thickness and the density of their own product. A density of 1.75 reproduces one US maker’s coverage chart for a 25 lb bag within about 3% for tile 8 × 8 in and larger with 1/8 to 1/4 in joints. Mosaics are the exception: for tile of 2 in or less the formula asks for noticeably more grout than that chart, so use the bag’s own coverage figure for them.
area = length × width, added up for each rectanglespace per tile = (tile length + joint) × (tile width + joint)tiles = area ÷ space per tiletiles to buy = tiles × (1 + waste % ÷ 100), rounded upboxes = tiles to buy ÷ tiles per box, rounded upgrout per area = (L + W) ÷ (L × W) × joint width × joint depth × densityHow many tiles and how much grout per 100 sq ft?
Computed with the formulas above for 1/8 in joints and a grout density of 1.75. Tiles up to 6 × 6 in are taken as 1/4 in thick, larger tiles as 3/8 in thick.
| Tile size | Tiles to cover 100 sq ft | With 10% extra | Grout |
|---|---|---|---|
| 4.25 × 4.25 in | 752.3 | 828 | 13.4 lb |
| 6 × 6 in | 383.8 | 423 | 9.5 lb |
| 12 × 12 in | 97.9 | 108 | 7.1 lb |
| 18 × 18 in | 43.8 | 49 | 4.7 lb |
| 24 × 24 in | 24.7 | 28 | 3.6 lb |
| 12 × 24 in | 49.2 | 55 | 5.3 lb |
| 6 × 24 in | 97.5 | 108 | 8.9 lb |
| 6 × 36 in | 65.1 | 72 | 8.3 lb |
| 24 × 48 in | 12.4 | 14 | 2.7 lb |
Grout weights are before any extra for mixing and cleanup. Wider joints need proportionally more grout.
Worked examples
12 × 24 in tile on a 12 × 10 ft floor
The floor is 12 × 10 = 120 sq ft. With 1/8 in joints each 12 × 24 in tile takes up 12.125 × 24.125 in, which is 2.03 sq ft, so 59.1 tiles cover the floor and 60 whole tiles is the minimum. A straight layout with 10% extra gives 65 tiles. If the box holds 8 tiles, that is 9 boxes, or 72 tiles.
For 3/8 in thick tile and a grout density of 1.75, the joints take 0.053 lb of grout per sq ft, 6.40 lb for the floor. With 10% extra for mixing and cleanup that is 7.04 lb: one 25 lb bag, or two 7 lb boxes.
12 × 12 in tile laid diagonally in an L-shaped kitchen
Split the L into two rectangles: 10 × 8 ft and 4 × 3 ft, which add up to 80 + 12 = 92 sq ft. Enter them as Area 1 and Area 2. With 3/16 in joints each 12 × 12 in tile takes up 1.03 sq ft, so 89.2 tiles cover the floor.
A diagonal layout starts at 15% waste, so you buy 103 tiles, or 11 boxes of 10. The grout comes to 10.8 lb with 10% extra, so one 25 lb bag is enough.
Should I use the nominal or the actual tile size?
Use the actual size when the box gives it, because nominal sizes are rounded. One US tile maker lists its nominal 12 x 24 in tile as 30 × 60 cm, which is 11.81 × 23.62 in. For the 120 sq ft floor in the first example, the actual size needs 61.0 tiles to cover it and 68 with 10% extra, three more than the 65 the nominal size suggests.
Check the box or the maker’s data sheet for the thickness as well, because it sets the joint depth and with it the amount of grout. The same sheet gives 9 mm for that tile, a little under 3/8 in.
How wide should grout joints be?
At least 1/8 in for rectified tile and 3/16 in for calibrated (pressed-edge) tile, according to the TCNA Handbook as quoted by Florida Tile. For an offset pattern with tile longer than 15 in on one side, the Handbook recommends an offset of no more than one third and a wider joint, because tiles are higher in the middle than at the edges.
Sanded grout is made for wider joints: the data sheet of one sanded grout gives a range of 1/8 to 1/2 in and points to non-sanded grout for joints up to 1/8 in. The calculator checks your joint against the TCNA minimums under the results.
Questions
How many tiles do I need for a 10 × 10 room?
You need 108 tiles of 12 × 12 in for a 10 × 10 ft room with 1/8 in joints, including 10% extra for cuts. The floor is 100 sq ft and each tile with its joint takes up 1.021 sq ft, so 97.9 tiles cover it exactly. With 12 × 24 in tile the same room takes 55 tiles, and with 18 × 18 in tile 49.
How much extra tile should I buy?
Buy about 10% more tile than the area needs for a straight or offset layout, the allowance one tile maker gives for cuts and breakage. The calculator starts diagonal layouts at 15% and herringbone at 20% because nearly every edge tile is cut. These are planning figures, not a standard, so use your installer’s number if you have one, and keep a few spare tiles for repairs.
How much grout do I need for 100 square feet?
About 5.3 lb of sanded grout covers 100 sq ft of 12 × 24 in tile with 1/8 in joints and 3/8 in thickness, before any extra. Smaller tile has more joint per square foot: 12 × 12 in tile needs 7.1 lb and 6 × 6 in tile (1/4 in thick) 9.5 lb. Add 10% for mixing and cleanup, as one grout maker advises.
What size grout joint should I use for 12 × 24 tile?
Use at least 1/8 in for rectified 12 × 24 in tile and 3/16 in for calibrated tile, the TCNA Handbook minimums as quoted by Florida Tile. In a brick pattern, the Handbook recommends offsetting tile longer than 15 in by no more than one third, and Florida Tile recommends a joint of at least 3/16 in for that kind of installation.
How many boxes of tile do I need?
Divide the tiles to buy by the pieces per box and round up: 65 tiles in boxes of 8 is 9 boxes, which hold 72 tiles. If the label gives only square feet per box, divide the face area of the tiles you need by that figure instead. Read the count on your own box, because the calculator’s starting figure is only a placeholder.
Do I include the grout joint when calculating tiles?
Yes, add one joint width to the length and the width of the tile. A 12 × 12 in tile with a 1/8 in joint takes up 1.021 sq ft instead of 1 sq ft, which saves about 2 tiles per 100 sq ft. With small tile and wide joints the difference grows: a 6 × 6 in tile with a 1/2 in joint takes up 0.293 sq ft, so 100 sq ft needs 341 tiles instead of 400.
Sources
- Florida Tile, Installation (checked October 19, 2026)TCNA Handbook minimum joints of 1/8 in for rectified and 3/16 in for calibrated tile; offsets of no more than 33% for tile longer than 15 in.
- Florida Tile, Pagosa collection sheet (100102LT) (checked October 19, 2026)Nominal 12x24 in tile listed as 30x60 cm, 9 mm thick.
- Custom Building Products, Polyblend Plus Sanded Grout (checked October 19, 2026)Coverage chart in sq ft per 25 lb bag by tile size and joint width, used to set the 1.75 density; joints from 1/8 to 1/2 in.
- Custom Building Products, Polyblend Plus Sanded Grout, data sheet TDS-360 (checked October 19, 2026)7 lb box and 25 lb bag; non-sanded grout for joints up to 1/8 in.
- LATICRETE, Project Estimator, grout coverage guidelines (checked October 19, 2026)Add 10% to calculated grout for waste, spillage and clean-up.
- Cégécol (Sika France), CARROJOINT PREMIUM data sheet (checked October 19, 2026)Grout consumption formula (L + l) × joint width × depth × density ÷ (L × l).
- Johnson Tiles (Australia), FAQs (checked October 19, 2026)Allow an extra 10% for cuts and wastage.
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