Tile Calculator – How Many Tiles and Boxes Do I Need?
Our free tile calculator tells you how many tiles and boxes you need for a floor, a wall, a shower, or a backsplash. Enter one or more areas, subtract cabinets or a tub, pick the tile size and grout joint, and choose the layout. You get the number of tiles with the right extra for cuts, the boxes to buy, the cost, and an estimate of the grout, ready to copy or print.
How to Use the Tile Calculator
- Enter the area. Type the length and width of the floor or wall in feet, or switch to “Area” if you already know the square footage.
- Add more areas. An L-shaped room is two rectangles. A bathroom can have a floor area and a shower wall in the same list.
- Subtract what you will not tile. For a kitchen island, a vanity, or a tub, add an area and check “Subtract this area (cabinet, tub, island).”
- Set the tile. Enter the tile length and width in inches, or tap a common size such as 12 × 24. Then choose the grout joint, from 1/16 to 1/4 inch.
- Choose the layout. Straight and offset layouts add 10% for cuts and breakage, diagonal adds 15%, and herringbone 20%. You can also type your own value.
- Enter the box size. Use tiles per box, or switch to area per box if the label shows square feet. Add the price per box or per square foot for the total cost.
- Add the tile thickness for the grout estimate, then copy or print the list.
How the Tile Count Is Calculated
Each tile covers its own size plus half a grout joint on every side. That is why the calculator adds one joint width to each tile dimension before dividing:
Tiles = area ÷ ((tile length + joint) × (tile width + joint))
Then it adds the extra for your layout and rounds up to whole tiles and whole boxes. For a quick check by hand, a 12 × 12 inch tile with a 1/8 inch joint covers 12.125 × 12.125 = 147 square inches, or 1.02 square feet.
Example: a 10 × 8 Bathroom Floor
The floor has 80 sq ft. A 12 × 24 inch tile with a 1/8 inch joint covers 2.03 sq ft. Without extra, that is 39.4, so 40 tiles. With 10% extra for a straight layout, 88 sq ft divided by 2.03 gives 43.3, so you buy 44 tiles. At 8 tiles per box, that is 6 boxes, or 48 tiles. The grout for 3/8 inch thick tile comes to about 4.3 pounds, so one 25 lb bag is plenty.
Example: a Kitchen With an Island
A 10 × 8 ft kitchen floor has an island of 5 × 2.5 ft that stays untiled. The area to tile is 80 − 12.5 = 67.5 sq ft. With 12 × 12 tiles set on the diagonal (15% extra), you need 67.5 × 1.15 ÷ 1.02 = 76.03, so 77 tiles. That is 10 boxes of 8 tiles, which cost $320 at $32 per box.
Tiles per 100 Square Feet
This table shows how many tiles cover 100 sq ft with a 1/8 inch joint (1/16 inch for the small sizes), without and with 10% extra. It is handy when you compare tile sizes in the store.
| Tile size | Area per tile incl. joint | Tiles per 100 sq ft | With 10% extra |
|---|---|---|---|
| 3 × 6 in (subway) | 0.129 sq ft | 776 | 854 |
| 4 × 4 in | 0.115 sq ft | 873 | 960 |
| 12 × 12 in | 1.02 sq ft | 98 | 108 |
| 6 × 24 in (plank) | 1.03 sq ft | 98 | 108 |
| 12 × 24 in | 2.03 sq ft | 50 | 55 |
| 18 × 18 in | 2.28 sq ft | 44 | 49 |
| 24 × 24 in | 4.04 sq ft | 25 | 28 |
How Much Extra Tile Should I Buy?
Every row and every wall ends with cut tiles, and some tiles break or have flaws. The extra depends mostly on the layout:
| Layout | Extra in the calculator | Why |
|---|---|---|
| Straight (grid) | 10% | Cuts only at the edges |
| Offset or brick | 10% | Some cut pieces can start the next row |
| Diagonal (45°) | 15% | Triangle cuts along every wall |
| Herringbone | 20% | Many angled cuts at the edges |
These are common rules of thumb from tile retailers and installers, not fixed rules. Small rooms with many corners need more, large open floors need less. Large tiles also break more easily, so be generous with big formats. Keep at least one unopened box after the job: tiles get discontinued, and a later repair with a different batch can look patchy.
Grout Joints and Grout Estimate
The joint width changes the look, the tile count, and the grout you need. Rectified tiles with straight, precise edges can take narrow joints of 1/16 to 1/8 inch. Tiles with less even edges need wider joints, often 3/16 to 1/4 inch. Many tile makers print the minimum joint on the box, so check it first.
The calculator estimates cement grout with a formula that many grout makers use:
Grout (kg per m²) = (A + B) ÷ (A × B) × joint width × tile thickness × 1.6
A and B are the tile length and width, and all sizes are in millimeters. The 1.6 stands for about 1.6 kg of grout per liter of joint. The calculator converts it to pounds and adds 10% reserve. Small tiles and wide joints need far more grout than large tiles: a 3 × 6 subway tile with a 1/16 inch joint takes about as much grout per square foot as a 12 × 12 tile with twice the joint width (at a typical thickness of 1/4 and 3/8 inch). Epoxy and urethane grouts have other weights, so follow the coverage chart on the bag.
After grouting, seal cement grout to keep out water and stains. Our guide to the best grout sealer compares penetrating and surface sealers and shows how to apply them.
Measuring Tips for Floors, Walls, and Backsplashes
- Measure to the walls, not to the baseboard. Tile usually runs under the baseboard or up to the wall with a small gap for expansion.
- Split odd rooms into rectangles. Add each one as its own area. A closet or a doorway nook is just one more line.
- Walls: measure each wall that gets tile and subtract windows, doors, or a tub with an area of their own.
- Backsplash: measure the length of the counter run times the height up to the cabinets, and subtract the window and outlets only if they are large.
- Shower: add each wall as its own area and include the ceiling if you tile it.
If you decide against new tile for now, old tile can sometimes be refreshed instead. Our guides on how to paint a bathtub and how to paint marble show what is possible with paint. For floors, see how to paint laminate flooring.
Before You Start Tiling
- Check the base. Tile needs a flat, stable, clean surface. Fill cracks in concrete first, for example with a product from our list of the best concrete crack fillers.
- Plan the layout. Dry-lay a row of tiles in both directions so that the cut pieces at the walls are not tiny slivers.
- Seal the edges. Use flexible caulk, not grout, where tile meets a tub, a counter, or a change of plane. Our article on RTV silicone explains the options.
- Glue small accents. For mirrors and small decor next to the tile, see how to glue a mirror to a wall.
For the full method, the Tile Council of North America publishes installation guidance that most US installers follow.
Metric Units and Privacy
Switch to metric to enter the room in meters and the tile in millimeters. The quick sizes then show common metric formats such as 30 × 60 or 60 × 60 cm, and the grout comes in kilograms with 5 or 25 kg bags. The calculator runs in your browser, needs no sign-up, and nothing you enter is sent anywhere. All results are estimates, and the box label of your tile and grout comes first.
More Free DIY Tools
All our tools are free, run in your browser, and need no account.
- Concrete Calculator: work out cubic yards and bags of concrete for slabs, footings, and posts.
- Board Foot Calculator: turn your cut list into board feet and lumber cost.
- Paint Calculator: find out how many gallons of paint your room needs.
Frequently Asked Questions
How Do I Calculate How Many Tiles I Need?
Divide the area by the area of one tile including the grout joint, then add 10 to 20% for cuts and breakage, depending on the layout. Round up to whole boxes.
How Many 12 × 24 Tiles Do I Need for 100 Square Feet?
With a 1/8 inch joint, one 12 × 24 tile covers about 2.03 sq ft. You need 50 tiles for 100 sq ft, or 55 with 10% extra.
How Many 12 × 12 Tiles Are in 100 Square Feet?
About 98 tiles with a 1/8 inch joint, or 108 with 10% extra. Without any joint, it would be exactly 100.
How Much Extra Tile Should I Buy for a Diagonal Layout?
Plan on about 15% for a diagonal layout and about 20% for herringbone, compared with about 10% for a straight grid.
Does the Grout Joint Change the Number of Tiles?
Yes, slightly. Each joint adds to the area one tile covers, so you need fewer tiles. With large tiles the difference is small, with mosaics and small tiles it is noticeable.
How Much Grout Do I Need?
It depends on the tile size, the joint width, and the tile thickness. For 12 × 24 tile, 3/8 inch thick, with a 1/8 inch joint, about 5 pounds covers 100 sq ft. Small tiles and wide joints need much more.
How Many Tiles Are in a Box?
It varies by size and brand. Large formats often come 4 to 8 per box, while 12 × 12 tiles often come 10 to 15 per box. Check the label, which also lists the square feet per box.
Is the Tile Calculator Free?
Yes. It is free, needs no account, works in imperial or metric units, and lets you copy or print the results.
Robert Thompson has worked as a self-employed carpenter for over 15 years. He lives with his family in Billings, Montana, where he also successfully operates his business as a woodworker. His main business is the complete interior construction of buildings. He is also passionate about creating high-quality wood furniture with epoxy and other items made from burl wood. Besides the woodwork, Robert is also a skilled DIY professional for all kinds of materials. He always has a solution ready for every craft and construction challenge. Originally, Robert studied civil engineering and has advanced degrees in carpentry and business management. Robert has been working for Craft Art since 2020 and enriches the blog with his immense knowledge and skills in the field of woodworking and home improvement. He writes the articles about DIY and Repair.
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