A tile calculator tells you three things: how much area you need to cover, how many tiles that requires, and roughly what the project will cost. The math itself is simple. Measure the space, divide it by one tile’s coverage, add extra for waste, then round up to a full box.
Here is the short version. For a rectangular room:
Square feet = length x width
Then:
Number of tiles = (square feet x 1.10) ÷ area of one tile
The 1.10 accounts for a common 10 percent waste allowance. The rest of this guide walks through each step in detail, including how the numbers change for showers, walls, irregular rooms, and installation cost.
What a Tile Calculator Actually Does
A tile calculator estimates how many tiles, boxes, or dollars a project needs based on the size of the surface and the size or coverage of the tile you plan to use. Depending on the calculator, it may also factor in waste percentage, box coverage, material price, and labor cost.
Before running any numbers, it helps to keep four measurements straight, since mixing them up is the most common source of a bad estimate:
- Room area: the total floor or wall space in the room.
- Tiled area: only the part that will actually be tiled. A 1,000 square foot house does not need 1,000 square feet of tile if part of that space is carpet, cabinetry, or an untiled closet.
- Individual tile area: how much surface one tile covers, based on its printed dimensions.
- Box coverage: the square footage listed on the box, which isn’t always a round number and isn’t guaranteed to match what the tile’s dimensions alone would suggest.
Get the tiled area right first. Every other number in this guide builds on it.
How to Calculate Square Footage for Tile
For a simple rectangular room, multiply length by width, both measured in feet:
Square feet = length x width
Example: A room measures 10 feet by 12 feet.
10 x 12 = 120 square feet
That 120 square feet is your starting point for every calculation that follows.
Irregular or L-shaped rooms
Most rooms are not perfect rectangles. When a space has an offset, a closet, or an L-shape, split it into smaller rectangles, calculate each one, then add the results.
Example: An L-shaped room breaks into two sections.
- Section A: 10 ft x 8 ft = 80 square feet
- Section B: 6 ft x 5 ft = 30 square feet
- Total: 80 + 30 = 110 square feet
If a section has an unusual angle you cannot break into rectangles, measure it as though it were the smallest rectangle that fully contains it, then treat the extra corner as part of your waste allowance rather than trying to calculate it exactly.
How to Calculate the Area of One Tile
Tile is usually sold with dimensions in inches, so you need to convert that to square feet before comparing it against your room. Since one square foot equals 144 square inches (12 inches x 12 inches), the formula is:
Tile area in square feet = (tile length in inches x tile width in inches) ÷ 144
| Tile Size | Calculation | Area per Tile |
|---|---|---|
| 4 x 4 in | 16 ÷ 144 | 0.11 sq ft |
| 6 x 6 in | 36 ÷ 144 | 0.25 sq ft |
| 12 x 12 in | 144 ÷ 144 | 1.00 sq ft |
| 12 x 24 in | 288 ÷ 144 | 2.00 sq ft |
| 18 x 18 in | 324 ÷ 144 | 2.25 sq ft |
| 20 x 20 in | 400 ÷ 144 | 2.78 sq ft |
| 24 x 24 in | 576 ÷ 144 | 4.00 sq ft |
These figures use the nominal, or labeled, dimensions of the tile. Actual physical size can differ slightly by manufacturer once grout joints and edge tolerances are factored in, so treat this chart as a planning tool and confirm coverage against the specific product you buy.
How Many Tiles Do I Need?
The base formula, before accounting for cuts and breakage, is:
Tiles needed = tiled area ÷ area of one tile
But buying exactly that number leaves no room for mistakes. A more realistic purchasing formula adds a waste allowance first:
Required area = tiled area x (1 + waste percentage)
Tiles to buy = required area ÷ area of one tile
Always round the final tile count up to a whole number, and up to a whole box when buying by the box.
Example: You need to cover 120 square feet with 12 x 12 inch tile, using a 10 percent waste allowance.
120 x 1.10 = 132 square feet
132 ÷ 1 = 132 tiles
That 10 percent figure is a common starting point, not a rule that applies to every job. The actual number depends on your layout, tile size, and how much cutting the room requires, which the next section covers.
Quick reference: 12 x 12 inch tile by area
Because so many projects use 12 x 12 tile (each covering exactly 1 square foot), here is that math worked out for common areas, using a 10 percent waste allowance:
| Area | Tiles Before Waste | Tiles With 10% Waste |
|---|---|---|
| 100 sq ft (10×10 room) | 100 | 110 |
| 120 sq ft (10×12 room) | 120 | 132 |
| 200 sq ft | 200 | 220 |
| 1,000 sq ft | 1,000 | 1,100 |
For a different tile size, divide the same square footage by that tile’s coverage instead. For example, 1,000 square feet in 12 x 24 inch tile (2 square feet each) needs 500 tiles before waste, or 550 with a 10 percent allowance.
How Much Extra Tile Should You Buy?
Waste is the material you need beyond the exact mathematical area, and it comes from a predictable set of sources: cuts around walls and doorways, corners, plumbing penetrations, broken or chipped pieces, and any pattern that requires matching veining or repeating a motif.
There is no single correct waste percentage for every project, but a few benchmarks are widely used across the industry:
- Simple, straight-set layout in a square or rectangular room: 10 percent is a common baseline, and it is the figure most manufacturers and retailers print on their packaging as a minimum overage recommendation.
- Diagonal layouts, herringbone, or other patterns with angled cuts: often 15 to 20 percent, since more of the tile at the edges gets cut into unusable pieces.
- Complex rooms with many corners, niches, or fixtures: can run higher still, and should be discussed with your installer rather than estimated from a general rule.
It is also worth setting aside a small amount of “attic stock,” meaning a few extra tiles kept in storage for future repairs. Retailers and manufacturers commonly suggest that the standard 10 percent overage already covers this, but if your tile is a limited run or a discontinued color, buying a little extra up front is cheaper than trying to find a dye-lot match years later.
How Many Boxes of Tile Do I Need?
Tile is typically sold by the box, so the final purchasing step is converting your required area into whole boxes:
Boxes needed = required tile area ÷ coverage per box
Always round up. A partial box still means buying the whole box.
Example: Your project needs 132 square feet after waste, and each box covers 15 square feet.
132 ÷ 15 = 8.8, which rounds up to 9 boxes
Box coverage is not standardized, even for tiles of the same nominal size. Two different 12 x 12 inch products can ship in boxes covering different totals, commonly somewhere in the range of 10 to 25 square feet depending on the brand and how many pieces are packed per carton. Always use the coverage figure printed on the box or listed on the product page rather than assuming a fixed number.
Shower Tile Calculator
Shower calculations work the same way as floor calculations, just applied separately to each wall and surface, since a shower is rarely one continuous plane.
Wall area = width x height
Example: Two shower walls, each 3 feet wide and 7 feet high.
One wall: 3 x 7 = 21 square feet
Two walls: 21 x 2 = 42 square feet
Add any additional walls the same way, then combine the totals. If a wall includes a large opening, such as a niche or a glass panel cutout, subtract that area once you know its size.
Do not combine the shower floor into the same total as the walls. They are different surfaces, and many installations use a smaller-format tile on the floor for slope and drainage reasons even when the walls use a larger tile.
Slip resistance matters as much as quantity
Quantity is only half the shower tile decision. For floor tile in a level interior area expected to be walked on when wet, including a shower floor, ANSI A137.1 (the ceramic tile standard referenced in the International Building Code) specifies a minimum wet dynamic coefficient of friction (DCOF) of 0.42 for products recommended for that use. That said, the standard itself is explicit that a DCOF of 0.42 or higher does not automatically make a tile suitable for every project: traffic, expected contaminants, and manufacturer guidance all factor into the right choice, and no floor tile should be treated as completely slip-proof. Check the specific product’s rated DCOF before buying, and lean toward a smaller format or a more textured finish on a shower floor, since more grout lines generally improve traction underfoot.
Wall Tile Calculator
For any rectangular wall, including a backsplash:
Wall area = width x height
For multiple walls, calculate each one and add them together:
Total wall area = Wall 1 + Wall 2 + Wall 3…
Example: One bathroom wall is 8 ft by 8 ft, and an adjoining wall is 6 ft by 8 ft.
Wall 1: 8 x 8 = 64 square feet
Wall 2: 6 x 8 = 48 square feet
Combined: 64 + 48 = 112 square feet
Subtract significant openings such as windows or medicine cabinets if they take up meaningful space, then apply the same waste percentage guidance covered above before converting to tiles or boxes.
Bathroom Tile Calculation
A full bathroom often includes several distinct tile surfaces that should be calculated separately rather than lumped into one number, since they frequently use different tile sizes or products:
- Bathroom floor
- Shower floor
- Shower walls
- Remaining bathroom walls (if tiled)
- Backsplash
For example, a bathroom might break down as a 50 square foot floor, 80 square feet of shower walls, and a 15 square foot vanity backsplash. Treat each as its own calculation, with its own tile choice and its own waste allowance, then total the costs separately if you are budgeting materials.
Tile Installation Cost Calculator
Cost is a separate calculation from quantity, and it breaks into two main parts: material and labor.
Material cost
If tile is priced per square foot:
Material cost = purchased tile area x price per square foot
If tile is sold by the box:
Material cost = number of boxes x price per box
Example: 10 boxes at $30 per box.
10 x $30 = $300
Labor cost
Labor cost = tiled area x labor rate per square foot
Example: 120 square feet at $8 per square foot.
120 x $8 = $960
Total project cost
Total = tile materials + installation labor + additional materials
Additional costs can include thin-set mortar, grout, backer board, waterproofing membrane, underlayment, trim pieces, old tile removal, subfloor repair, and disposal. Not every project needs every item.
What tile installation actually costs in the U.S. right now
According to Angi’s 2026 cost data, the national average tile installation project runs about $2,000, with most homeowners spending between $400 and $4,250 depending on room size, tile type, and layout complexity. Tile material alone typically runs $5 to $45 per square foot, and labor typically runs $3 to $15 per square foot, with some contractors billing $60 to $120 per hour instead of by square footage.
By project type, Angi’s 2026 figures show:
| Project | Typical Cost Range |
|---|---|
| Kitchen floor | $800 to $3,000 |
| Backsplash | $480 to $1,500 |
| Bathroom floor | $300 to $1,300 |
| Shower | $400 to $5,000, averaging around $2,700 |
Beyond materials and labor, budget for a few common add-ons: removing old tile runs about $2 to $7 per square foot, subfloor repair runs about $3 to $10 per square foot, waterproofing a shower typically adds $450 to $750, and general disposal fees add roughly $150 to $200.
These are national ranges, not a quote. Actual pricing depends heavily on your region, the specific tile product, and the condition of the surface underneath, so treat any calculator’s cost output as a planning estimate and confirm final numbers with a local contractor.
Worked Examples
10 x 10 room, 12 x 12 tile, 10% waste
Area: 10 x 10 = 100 sq ft
Tiles before waste: 100 ÷ 1 = 100
With waste: 100 x 1.10 = 110 tiles
10 x 12 room, 12 x 12 tile, 10% waste
Area: 10 x 12 = 120 sq ft
Tiles before waste: 120 ÷ 1 = 120
With waste: 120 x 1.10 = 132 tiles
200 sq ft, 12 x 24 tile, 10% waste
Tile area: 2 sq ft each
Required area: 200 x 1.10 = 220 sq ft
Tiles: 220 ÷ 2 = 110 tiles
100 sq ft, 20 x 20 tile, 10% waste
Tile area: 400 ÷ 144 = 2.78 sq ft
Required area: 100 x 1.10 = 110 sq ft
Tiles: 110 ÷ 2.78 ≈ 39.6, rounds up to 40 tiles
1,000 sq ft project, box coverage 15 sq ft, 10% waste
Required area: 1,000 x 1.10 = 1,100 sq ft
Boxes: 1,100 ÷ 15 ≈ 73.3, rounds up to 74 boxes
Which Tile Size Is Best?
There is no universal best size. It depends on the room and the look you want.
For a bedroom: larger tiles cover more area with fewer grout lines and a cleaner look, while smaller tiles allow more design flexibility and pattern work. Compare actual box coverage and price per square foot rather than choosing based on the room’s total size alone.
For a bathroom floor: smaller formats can make it easier to slope the floor toward a drain, since more grout joints give the installer more flexibility. Any tile used on a shower floor should carry a wet DCOF rating suitable for that application, as covered above.
For bathroom walls or shower walls: larger formats reduce grout lines but require a flatter substrate and more careful handling and cutting around niches and plumbing.
What Type of Tile Is Cheapest?
There is no single cheapest tile, since pricing depends on material, brand, finish, and supplier. As a general pattern, ceramic tile tends to sit at the lower end of the price range compared to premium stone, glass, or specialty products, but individual products vary widely even within the same category. When comparing options, calculate the price per square foot rather than comparing box prices directly, since box sizes differ:
$30 box ÷ 15 sq ft coverage = $2 per square foot
That per square foot figure is the number that actually lets you compare two different products on equal footing.
Common Tile Calculation Mistakes
- Using total house or room square footage instead of tiled area. A 1,000 square foot house rarely needs 1,000 square feet of tile once cabinets, other flooring, and untiled rooms are excluded.
- Confusing tile size with box coverage. A 12 x 12 tile covers 1 square foot, but the box it comes in may cover a different total depending on how many pieces are packed inside.
- Skipping the waste allowance entirely. Buying the exact mathematical area leaves nothing for cuts or breakage.
- Applying the same waste percentage to every layout. A straight-set rectangular room and a diagonal or herringbone pattern do not need the same overage.
- Rounding down instead of up. If the math gives 8.2 boxes, you need 9, not 8.
- Ignoring doors, windows, and cabinets when calculating walls. Subtract significant openings once you know their size.
- Treating floor and wall tile as one calculation. A bathroom floor, shower walls, and a backsplash may use different products and should be calculated separately.
- Estimating cost from square footage alone. Material and labor pricing depend on the specific product and project conditions, not just total area.
Formula Cheat Sheet
- Floor area: length x width
- Wall area: width x height
- Tile area (inches to sq ft): (tile length x tile width) ÷ 144
- Tiles before waste: project area ÷ tile area
- Required area after waste: project area x (1 + waste percentage)
- Tiles after waste: required area ÷ tile area
- Boxes needed: required area ÷ coverage per box
- Material cost: purchased area x price per sq ft, or boxes x price per box
- Labor cost: tiled area x labor rate per sq ft
- Total cost: materials + labor + additional materials and services
Frequently Asked Questions
How do you calculate square feet for tile?
Measure length and width in feet and multiply them. For irregular rooms, split the space into rectangles, calculate each one, and add the totals together.
How many tiles do I need for 100 square feet?
It depends on tile size. A 12 x 12 inch tile covers 1 square foot, so you need 100 tiles before waste. A 12 x 24 inch tile covers 2 square feet, so you need 50 tiles before waste.
How many 12 x 12 tiles do I need for 200 square feet?
200 tiles before waste, since each tile covers 1 square foot. With a 10 percent allowance, that becomes 220 tiles.
How many square feet does a box of 12 x 12 tile cover?
There is no fixed answer. Box coverage varies by product and can differ even among tiles of the same nominal size, so always check the specific box or product listing.
How many boxes of tile do I need for a 3 bedroom house?
Bedroom count alone will not tell you. Measure the actual surfaces that will be tiled, add a waste allowance, and divide by the coverage per box for the product you choose.
How much does it cost to tile 100 square feet?
Cost depends on the tile product, labor rate, and site conditions. Based on 2026 U.S. data, material and installation together commonly fall somewhere between $500 and $4,500 for 100 square feet, though high-end materials can push that higher.
What is the price of 12 x 24 inch tile?
There is no single price. Tile cost varies by material and brand, so compare products using price per square foot rather than a flat per-tile price.
How much does tile installation cost per square foot?
As of 2026, labor alone commonly runs $3 to $15 per square foot, while total installed cost, including materials, commonly runs $5 to $45 per square foot depending on the tile selected.
Final Takeaway
The tile math itself never really changes: measure the area, calculate the coverage of one tile, add a waste allowance suited to your layout, convert to tiles or boxes, and round up. Cost is a separate calculation on top of that, combining material price with a labor rate and any prep work the space needs.
The most reliable numbers will always come from the product you actually buy: the coverage printed on the box, the manufacturer’s application guidance, and a waste allowance matched to your real layout rather than a generic percentage. Calculate each surface- floor, wall, shower, or backsplash- on its own, and the final purchasing quantity will be far more accurate than treating the whole project as one number.