Tile calculator: how many tiles do I need?
Enter the room, the tile size and how much waste you want to allow. You get tiles, boxes and a rough bill for the tile itself — the part of the job you can price exactly.
Tile quantity & cost
Live estimateBuy
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Tiles only — thinset, grout, backer board and trim are extra. Keep one spare box for future repairs.
Tile is the least forgiving flooring material to under-buy. Running out mid-job means a second trip, a different production run, and a visible colour shift in the middle of the room. Buying one box too many costs $40–$80 and sits quietly in the garage until you need it.
How this calculator works
- Floor area = room length × room width. A 10 × 12 ft room is 120 sq ft.
- Area with waste = floor area × (1 + waste %). At 10%, 120 sq ft becomes 132 sq ft.
- Tile area = (tile width in inches × tile length in inches) ÷ 144. A 12 × 24 inch tile is 288 ÷ 144 = 2 sq ft.
- Tiles needed = area with waste ÷ tile area, rounded up. 132 ÷ 2 = 66 tiles.
- Boxes = tiles ÷ tiles per box, rounded up. 66 ÷ 6 = 11 boxes.
- Cost = boxes × price per box. Boxes, not tiles, is what you pay for.
Round only once, at the box. Rounding the square footage up, then the tile count up, then the boxes up can add a whole extra box to a small room.
Measuring a room that is not a rectangle
Most rooms are not one clean rectangle. Break the floor into rectangles, measure each one, and add the areas together:
- L-shaped room — split it into two rectangles along the inner corner, then add both areas.
- Room with an alcove or closet — measure the closet as its own rectangle if you are tiling into it. Many people tile closets, and forgetting one is a classic 20 sq ft miss.
- Angled or bay window area — measure the widest length and width of that section and treat it as a rectangle. The overage is small and the waste factor covers it.
For anything with more than two inside corners, measure in inches rather than feet. Fractions of a foot are where errors creep in.
Why the waste allowance matters more than you think
Every cut tile produces at least one offcut, and offcuts only become useful if they happen to fit somewhere else. In a simple square room laid straight, 10% covers it comfortably. Change the layout and the number moves:
| Layout | Waste | Why |
|---|---|---|
| Straight lay, square room | 5% | Few cuts, all at the perimeter |
| Straight lay, normal room | 10% | Doorways, corners, one or two breaks |
| Diagonal lay | 15% | Every perimeter tile is a triangle |
| Herringbone or chevron | 20% | Two cut angles per row, pattern must stay aligned |
| Small tiles (under 6 in) | +5% | More pieces, more breakage handling |
Add a little more if the room has more than two doorways, a curved wall, or a floor drain that has to be cut around. Read more in how much tile waste to allow.
Nominal size vs actual size
A tile sold as 12 × 24 inches is usually a hair under 12 × 24, because the grout joint is designed to bring it back to the nominal dimension. With a 1/8 inch joint, two tiles plus the joint measure exactly 24 inches. That means grout lines do not change your quantity much — but it does mean you should not measure a tile with a tape and expect a clean number.
Where it does matter is rectified tile, which is cut square after firing and can be laid with a 1/16 inch joint. Rectified tile is more expensive, needs a flatter substrate, and buys you almost no extra coverage. Choose it for the look, not the maths.
What the tile itself costs
| Tile type | Price per sq ft | Typical use |
|---|---|---|
| Ceramic, basic | $1–$3 | Bathroom floors, laundry rooms |
| Porcelain, mid-range | $3–$6 | Kitchens, hallways, whole-house floors |
| Porcelain, large format | $5–$10 | Open-plan living areas |
| Wood-look plank tile | $4–$9 | Living rooms, bedrooms, basements |
| Natural stone | $7–$15+ | Entries, bathrooms, feature floors |
Those are material prices only. Installation runs $5–$12 per sq ft on top, more for large format or natural stone. See what it costs to tile a floor for the full installed picture.
What this calculator leaves out
- Thinset — a 50 lb bag covers roughly 60–95 sq ft with a 1/2 inch trowel, depending on tile size.
- Grout — a 25 lb bag covers 100–150 sq ft at a 1/8 inch joint. Wider joints use dramatically more.
- Underlayment — cement backer board or an uncoupling membrane, $1–$3 per sq ft.
- Trim and transitions — thresholds, schluter strip and baseboards are priced per linear foot.
- Spacers, wedges, blades — $30–$60 of consumables on a typical room.
Frequently asked questions
How many tiles do I need for a 10x12 room?
A 10x12 ft room is 120 sq ft. With a standard 10% waste allowance you need 132 sq ft of tile. In 12x24 inch tile (2 sq ft each) that is 66 tiles. At 6 tiles per box, buy 11 boxes. The calculator above does this for any room and tile size.
How much extra tile should I buy?
Add 10% for a straight lay in a simple rectangular room, 15% for diagonal or rooms with several doorways and corners, and 20% for herringbone or other complex patterns. Then buy one extra box and keep it sealed — it is the only way to match the dye lot if you ever need a repair.
Do I subtract cabinets or a bathtub from the floor area?
Subtract anything that sits on the floor and will never be tiled over: a bathtub, a shower pan, a kitchen island. Do not subtract a vanity or a toilet — flooring almost always runs underneath those, and leaving the tile out makes future replacement much harder.
Should I measure the room or the tile layout?
Measure the room. Tile is cut to fit at the edges, so the floor area is the room area. Only measure the layout separately if you want to know how many full tiles run across a wall, which matters for centring a pattern but not for quantity.
Does the calculator include mortar, grout or backer board?
No, it covers tile only. Budget roughly 10–20% of the tile cost for thinset and grout, and another $1–$3 per sq ft if you need cement backer board or an uncoupling membrane over a wood subfloor.