How Many Tiles Do I Need?
Tiles are bought by the box, but priced by how many you waste getting the layout right. Here is how to turn your room and tile size into an accurate tile - and box - count.
By the Calculate My Reno Team / Published
Skip to the tool
Open the Tile Calculator
Tiling is unforgiving of a bad count: run short and a later box from a different batch may not match. Here is how to get the number right the first time.
The formula
tiles = ceil( room area ÷ (tile area incl. grout) × wastage )
The calculator divides your floor or wall area by the footprint of one laid tile - the tile face plus one grout joint - then adds wastage and rounds up. Let the tile calculator handle it, or follow the steps below.
Step 1: Measure the area
- Floors: length × width, measured at floor level along the skirting.
- Walls: width × tiled height for each wall, added together.
- Irregular spaces: split into rectangles, work out each, and add them.
Step 2: Account for the grout gap
Each tile sits with a grout joint around it, so it effectively covers its own size plus the gap. Ignoring this overestimates the count - especially with small tiles and wide joints, where you could buy boxes you do not need. A good calculator folds the gap into the tile footprint.
Step 3: Add wastage
You always buy extra for cut tiles at the edges, breakages, and spares. The allowance depends on the layout:
| Layout | Allowance |
|---|---|
| Straight grid | 10% |
| Offset / diagonal | 15% |
| Herringbone / chevron | 20% |
See how to calculate tile wastage for why patterns waste more.
Step 4: Turn tiles into boxes
Tiles are sold by the box, so divide your total tile count by the tiles-per-box figure on the label and round up. The tile calculator returns both the tile count and the number of boxes.
Worked example
A 12 ft × 12 ft floor, 12-inch tiles, straight grid:
- Area: 12 × 12 = 144 sq ft.
- Tiles before waste: 144 (one tile per sq ft).
- Add 10%: about 159 tiles.
Switch to 24-inch tiles and you need just 36 + waste ≈ 40 tiles - bigger tiles, far fewer of them.
The one rule
Buy all your tiles at once and check the batch/shade number matches on every box. Tile colour drifts between production runs, so topping up later risks a visible mismatch across the surface.
Frequently asked questions
How many tiles do I need for a 12x12 room?
A 12 ft × 12 ft room is 144 square feet. With 12-inch tiles you need 144 tiles before wastage, or about 159 with the standard 10% allowance. With larger 24-inch tiles you need 36, or about 40 with wastage. Enter your exact room and tile size in the tile calculator for a precise count.
Does the grout gap change how many tiles I need?
Slightly. Each grout line means a tile covers a little more floor than its own face, so wider gaps reduce the tile count marginally. The effect is small for large tiles but noticeable with small ones, which is why a good calculator includes the gap in its maths.
How many tiles come in a box?
It varies by size and brand - large-format tiles often come 3–5 per box, small ceramics 10–25 per box. Check the box label for the count or the coverage in square feet/metres, then divide your total tile count by the per-box figure to get the number of boxes.