Tile Calculator: How Many Tiles Do You Need for Any Room?
Calculate tile quantity for floors, walls, and backsplashes. Includes waste factor for straight, diagonal, and pattern layouts, plus grout and adhesive estimates.
The tile math is simple. The waste factor is where people get tripped up — especially on diagonal installations or rooms with lots of angles and obstacles. Order too little and you may not find a match later; tiles are batch-produced and colors vary between lots.
The CalcHub Tile Calculator calculates tile count, grout quantity, and adhesive coverage for any room and layout pattern.
The Basic Calculation
Tiles Needed = Room Area ÷ Tile AreaThen add a waste factor, then divide by the number of tiles per box.
For a 12 ft × 14 ft bathroom floor using 12"×12" tiles:
- Room area: 168 sqft
- Tile area: 1 sqft each
- Raw count: 168 tiles
- Add 10% waste: 185 tiles
- If box has 12 tiles: 16 boxes (round up from 15.4)
Waste Factors by Application
| Layout/Application | Waste Factor | Notes |
|---|---|---|
| Straight lay, simple room | 5–8% | Minimal cuts |
| Straight lay, complex shape | 10% | More edge cuts |
| Diagonal (45°) | 10–15% | Corner cuts dramatically increase |
| Herringbone | 15–20% | Many short cuts |
| Large format tile (24"+) | 10% | Fewer pieces but cuts are wasteful |
| Backsplash with outlets | 10–15% | Notch cuts around boxes |
Tile Size vs. Room Size
| Room Size | Recommended Tile Size | Avoid |
|---|---|---|
| Small bathroom (under 50 sqft) | 4"×4" to 12"×12" | 24"+ tiles feel overwhelming |
| Medium bathroom | 12"×12" to 18"×18" | — |
| Large bathroom/master | 18"×18" to 24"×24" | — |
| Kitchen floor | 12"×12" to 18"×18" | Very small mosaic (grout maintenance) |
| Backsplash | 3"×6" subway, 4"×4", or mosaic | Large format harder around cabinets |
| Large open floor | 24"×24" to 36"×36" | — |
Grout Estimation
Grout quantity depends on tile size and joint width:
| Tile Size | Joint Width | Coverage per 10-lb bag |
|---|---|---|
| 4"×4" | ⅛" | ~50 sqft |
| 6"×6" | ⅛" | ~75 sqft |
| 12"×12" | 3/16" | ~100 sqft |
| 18"×18" | ¼" | ~125 sqft |
| 24"×24" | ¼" | ~150 sqft |
| 3"×6" subway | 1/16" | ~30 sqft |
Adhesive (Thinset) Coverage
Thinset mortar coverage per 50 lb bag:
- Combed trowel (⅜" V-notch): 40–50 sqft
- Combed trowel (½" square-notch, for large tile): 30–40 sqft
For 168 sqft: roughly 4 bags of thinset using standard ⅜" notch.
Don't Forget Trim and Transitions
- Bullnose tiles: For exposed wall tile edges (top of backsplash, shower bench edges)
- Quarter-round or Schluter strip: Transitions between tile and other flooring
- Tile spacers: Choose your grout joint width and get the matching spacers
- Grout sealer: Required for porous tiles and grout joints in wet areas
How do I tile around a toilet or vanity?
Measure and cut around obstacles. For a toilet flange, you'll need a hole saw or tile nippers to create a circular cut. Plan your tile layout so cut tiles at obstacles are as large as possible — cut tiles less than half the tile width look awkward.
Can I tile over existing tile?
Sometimes — if the existing tile is firmly adhered (no cracks or hollow spots), the substrate is solid, and the added height (¼"–⅜") works with doors and transitions. Check the weight capacity of the floor first, especially on upper floors.
What's the difference between floor tile and wall tile?
Floor tile has a PEI (porcelain enamel institute) hardness rating and often has a textured surface for slip resistance. Wall tile can be softer and smoother because it doesn't bear foot traffic. Using wall tile on floors is not code-compliant. Using floor tile on walls is fine.
Related Tools
- Flooring Calculator — for hardwood, LVP, and carpet
- Grout Calculator — detailed grout volume calculations
- Concrete Calculator — floor slab that goes under the tile