Tiling a room looks simple until you stand in the tile aisle staring at 20 square boxes and realize one wrong guess means either a re-order trip with a 2-week wait, or a garage full of leftover boxes you cannot return. This tile calculator removes that guesswork: enter the room size, the tile size, and how many tiles come in a box, and it tells you exactly how many tiles, whole boxes, bags of grout, and dollars you need — including the 10% waste allowance every professional builds in.
Adjust any field and the numbers update instantly. Run a few scenarios with different tile sizes or price points before you buy, so the estimate on screen matches the quote from your installer.
How to Use
- Enter the Room Length and Room Width in feet. Measure the floor (or wall) where the tile will actually go, not the room's nominal dimensions — subtract a closet that you will not tile.
- Type the Tile Length and Tile Width in inches. The most common wall tile is 12 × 12 inches, while floors often use larger 12 × 24 or 18 × 18 inch planks.
- Set the Waste Allowance. The default 10% covers cuts around doorways, pipes, and any broken tiles. Switch to 15% if you are laying tiles on the diagonal or picking from mixed dye lots.
- Enter how many tiles come in one box in Tiles per Box. This number is printed on every retailer's box — 10, 8, and 6 are typical.
- Add the Price per Box to see the estimated material cost. Leave it at zero if you only want the quantity.
The result card shows the room area in square feet, the total tiles needed (already inflated for waste), the whole boxes you must buy, the estimated tile cost, and a rough count of 50-pound grout bags.
The Tile Math
The core takeoff is straightforward division, which is why every contractor uses the same method:
Tiles needed = (Room length × Room width) ÷ (Tile length × Tile width ÷ 144)
The ÷144 converts the tile area from square inches into square feet, because there are 144 square inches in one square foot. On a 12 × 12 inch tile, that works out to exactly 1 square foot per tile, so a 120-square-foot room needs about 120 tiles before waste.
Because tile is sold in sealed boxes, the calculator then rounds the inflated tile count up to whole boxes — you cannot buy 0.3 of a box. Rounding up is also your safety net: if a box arrives with cracked tiles or you miscut one, you do not have to wait weeks for a second shipment from the same dye lot.
Worked example: a 12 ft × 10 ft living room is 120 sq ft. With 12 × 12 inch tiles and 10% waste, you need 132 tiles. At 10 tiles per box that is 13.2 boxes, rounded up to 14 boxes. At $35 per box the material cost is $490, and the floor needs roughly 3 bags of grout.
Why the 10% Waste Allowance Matters
Beginners order the exact square footage and end up short. Every tile job produces offcuts: tiles must be cut to fit around the perimeter, around toilet flanges, around wall corners, and at transitions to other flooring. Thin tiles crack during transport and installation, and occasional boxes come from slightly different dye lots that do not match side by side.
The trade is deliberate: buying 10–15% extra costs a little more up front, but it guarantees all tiles come from the same dye lot and avoids a second order where the new batch may not match. Unopened boxes are almost always returnable within 90 days at major home improvement chains, so the insurance is cheap.
Examples
Example 1 — A standard kitchen. A kitchen measures 12 ft by 10 ft (120 sq ft), tiled with 12 × 12 inch ceramic tiles at 10 tiles per box and 10% waste. The calculator returns 132 tiles, 14 boxes, about $490 at $35 per box, and 3 grout bags. This is the default scenario and the number most homeowners should expect for an average kitchen.
Example 2 — Large-format floor tile. A 10 ft × 12 ft room (120 sq ft) tiled with 18 × 18 inch planks. Each tile covers 2.25 sq ft, so raw tile count is about 53.3; with 10% waste that is 58.7 tiles. At 8 tiles per box you buy 8 boxes — about $336 at $42 per box. Fewer, bigger tiles means fewer grout lines but each cut is more waste.
Example 3 — A large commercial space. A 1,000,000 ft × 100 ft warehouse floor tiled with 24 × 24 inch commercial tile at 4 tiles per box. The area is 100,000,000 sq ft; with 10% waste you need 27,500,000 tiles, which rounds up to roughly 6,875,001 boxes — about $412,500,060 at $60 per box. Run a scenario like this to confirm your estimator scales to whole-building takeoffs without rounding errors.
FAQ
How many tiles do I need for a 12×12 room?
A 12 ft × 12 ft room is 144 square feet. With standard 12 × 12 inch tiles (1 sq ft each) and a 10% waste allowance, you need about 159 tiles, which rounds up to 16 boxes at 10 tiles per box. Switch your tile size in the calculator to see the exact count for your project.
How much extra tile should I order for waste?
Plan on 10% extra for a simple straight lay on square rooms. Bump it to 15% for diagonal, herringbone, or patterned layouts that produce more offcuts, and to 20% for rooms with many angles, pipes, or custom cuts. Always buy the full order at once so every box shares the same dye lot.
How many square feet does a 12×12 tile cover?
A 12 × 12 inch tile covers exactly 1 square foot. For other sizes, multiply length × width in inches and divide by 144: an 18 × 18 inch tile is 2.25 sq ft, a 12 × 24 inch tile is 2 sq ft, and a 6 × 6 inch tile is 0.25 sq ft.
How do I calculate grout needed for tile?
A standard 50-pound bag of grout covers roughly 50 square feet of floor for typical 1/8 to 1/4 inch joints. So a 120 sq ft room needs about 3 bags. Wide grout joints, textured tile, and natural stone require more; thin joints on large-format tile require less.
Why does the calculator round up to whole boxes?
Tile is sold in sealed, unopenable boxes at the retail price per box. Buying exactly 13.2 boxes is impossible, and rounding down leaves you short. The calculator rounds up to the next whole box, which doubles as your spare-tile supply for future repairs and cracked replacements.
Does this calculator work for walls and backsplashes?
Yes. Enter the wall length and width in feet and the tile size in inches exactly as you would for a floor. A kitchen backsplash of 12 ft × 1.5 ft, for example, is 18 sq ft and needs roughly 20 tiles with 10% waste — usually one or two boxes.
Disclaimer
This tile calculator is provided for informational purposes only and does not constitute construction, contracting, or design advice. Tile counts, box quantities, grout bags, and cost estimates are approximations based on the dimensions you enter; actual material requirements vary by tile size, layout pattern, wall and floor condition, and waste rate. Always confirm quantities with your tile retailer or installer, and keep leftover boxes for future repairs.