How Much Tile for a 15×15 Room?
A 15 × 15 ft room is 225 ft², which needs 243 tiles of tile with 10% allowed for cuts and waste. Order 243 tiles — tile is boxed by the square foot (10–15 ft² per box); buy an extra box for future repairs.
Other room sizes
Order 243 tiles — tile is boxed by the square foot (10–15 ft² per box); buy an extra box for future repairs.
- Area
- 225 ft²
- Unit 12×12″ + 0.125″ joint
- 0.98 per ft²
- Net tiles
- 220
- Waste / cuts 10%
- + 23
- Tiles to buy
- 243
- Thinset mortar, 50 lb
- 4 bags
- Grout, 25 lb
- 3 bags
- Materials + delivery$1.50–$6 / ft² · Sep 2026
- $338 – $1,350
- Installed (with labor)typ. $2,475
- $1,463 – $4,725
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What will this tile job cost?
See the installed price range for these quantities and get up to 3 quotes from local contractors. Free, no obligation.
Different size or depth?
Open the full tile calculator to change every input, pick a material and see truckloads.
How to calculate tile by hand
Tiles = Area (ft²) ÷ [(L + joint) × (W + joint) ÷ 144] × (1 + waste)
Worked example
- Area: 10 ft × 8 ft = 80 ft².
- A 12 × 12″ tile with ⅛″ joints occupies 12.125² ÷ 144 = 1.02 ft² → 0.98 per ft².
- Net: 80 × 0.98 = 78.4 tiles; with 10% for cuts, 86.2 → 87 — about 8 boxes of 11.
- Also: thinset 80 ÷ 60 = 2 × 50 lb bags; grout 1 × 25 lb bag.
- 12 × 12″ tiles per ft²
- ≈ 1.0
- 12 × 24″ tiles per ft²
- ≈ 0.5
- 3 × 6″ subway per ft²
- ≈ 7.5
- Thinset, ¼″ square notch
- ≈ 60–80 ft² per 50 lb
Questions crews ask
How many tiles do I need?
Divide the area by the tile face plus grout joint. A 12 × 12″ tile with ⅛″ joints is about 1 per square foot, so a 10 × 8 ft floor needs 80, or 88 with 10% for cuts. Most 12 × 12″ tile comes 11 to a box (about 11 ft²), so that is 8 boxes.
How much extra tile should I buy?
10% for a straight layout in a rectangular room, 15% for diagonal, herringbone or a room with many corners, 20% for natural stone with colour variation. Keep a spare box — dye lots change and a cracked tile is otherwise unmatchable.
How much thinset do I need?
A 50 lb bag covers 60–80 ft² with a ¼″ square-notch trowel (12 × 12″ tile), 40–50 ft² with a ½″ notch for large-format tile, and 90–100 ft² with a 3/16″ V-notch for mosaics. The calculator uses 60 ft² per bag.