Calculate Tiles Needed For Floors, Walls & Ceilings
Calculate tiles for walls, floors, or entire rooms
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How to Calculate Tiles for Any Room
Working out how many tiles you need shouldn't involve guesswork. Our tile calculator handles the maths, but understanding the process helps you order with confidence.
Anyone who's run out of tiles mid-project knows the frustration. You're covered in adhesive, the shop's closed, and matching the batch later isn't guaranteed. Getting your calculations right the first time saves money, time, and stress.
This guide walks through tile calculation step by step, explains what affects your final count, and shows you how to use our calculator to get accurate results quickly.
The calculation basics
At its simplest, tile calculation divides your wall or floor area by the coverage of each tile. A 3m × 2.4m wall gives you 7.2m² to cover. If your tiles are 300mm × 300mm (0.09m² each), you'd need 80 tiles exactly.
But exact calculations rarely work in practice. Here's why:
Grout joints matter
Each tile needs space around it for grout. A 300mm tile with 3mm joints effectively covers 303mm × 303mm. Those millimetres add up across a whole wall.
Edges need cutting
Unless your room dimensions perfectly match your tile size (they won't), you'll cut tiles at edges, corners, and around obstacles.
Breakages happen
Even professionals break tiles. Porcelain snaps if you look at it wrong. Having spares means you're not scrambling for one more tile.
What affects your tile count
Room shape
Square rooms are straightforward. L-shaped rooms, alcoves, and angled walls increase cutting waste. A bathroom with a separate shower area might need 15% extra tiles compared to 10% for a simple square room.
Tile size and pattern
Larger tiles mean fewer grout lines and often less wastage, but they're harder to work with in small spaces. Small mosaics reduce cutting waste but take longer to install.
| Tile Size | Typical Wastage | Why |
|---|---|---|
| Small (under 200mm) | 5-10% | Less cutting waste, easier to fit awkward spaces |
| Medium (200-400mm) | 10% | Good balance of coverage and flexibility |
| Large (over 400mm) | 10-15% | More waste from edge cuts, harder to handle |
| Diagonal/herringbone | 15-20% | Angled cuts at all edges create more waste |
Obstacles and openings
Every door, window, socket, and pipe means cuts. Bathrooms are notorious – between the toilet, basin, shower screen, and radiator pipes, you might cut every third tile.
Understanding wastage percentages
Wastage isn't just about breakages. It covers all the tiles you can't use:
Edge cuts: That 300mm tile at the end of a 2.7m wall leaves you with an unusable 270mm offcut.
Complex cuts: L-shaped cuts around pipes often mean sacrificing most of a tile for one small section.
Breakages: Drops, bad cuts, tiles cracking on uneven surfaces – it happens.
Future repairs: Keep spares from the same batch for replacing damaged tiles later.
The 10% rule works for most projects. Simple rooms might need just 5-8%. Complex layouts, diagonal patterns, or first-time tilers should plan for 15% or more.
Using our tile calculator
Our calculator handles the maths, but you still need accurate measurements. Here's how to get the best results:
Step 1: Measure your areas
Measure each wall or floor section separately. For walls, measure from floor to ceiling (or to where you'll stop tiling). Don't round measurements – enter 2.43m, not "about 2.5m".
For L-shaped rooms or areas with alcoves, add each section as a separate area in the calculator. This gives more accurate results than trying to calculate one complex shape.
The calculator lets you switch between metric and imperial units. Click the unit indicator to cycle through metres, feet, centimetres, millimetres, and inches.
Step 2: Account for obstacles
Subtract areas you won't tile – windows, doors, shower screens, mirrors. Measure these carefully and add them as obstructions. For small obstacles like sockets, you might skip this step and let the wastage allowance cover it.
Step 3: Enter tile dimensions
Use the actual tile size, not the nominal size. A "300mm" tile might actually measure 298mm. Check the box or measure a sample. Enter your grout joint width too – typically 2-3mm for walls, 3-5mm for floors.
Step 4: Set your wastage
Start with 10% for standard installations. Increase it for:
- Your first tiling project (15%)
- Diagonal or pattern layouts (15-20%)
- Natural stone that's prone to breaking (15%)
- Rooms with lots of obstacles (12-15%)
Step 5: Add costs (optional)
Enter either the price per tile or per box. If using box prices, tell the calculator how many tiles come in each box. It'll work out how many boxes you need and show any spare tiles.
Don't forget adhesive and grout
The calculator estimates these materials too, but coverage varies by product and application method.
For spacers, the calculator estimates roughly one spacer per tile plus 10% extra. Buy more than you think – they're cheap and you'll drop half of them behind the bath.
Tips from professional tilers
"I always tell customers to order 15% extra for their first tiling job. Yes, it costs more upfront, but it's nothing compared to the cost and hassle of running out. The leftovers are your insurance policy."
Ready to calculate?
Getting your tile count right means your project runs smoothly. No emergency trips to the tile shop, no settling for a different batch, no explaining to your partner why the bathroom's been half-tiled for three weeks.
Our calculator handles the number-crunching. You just need accurate measurements and realistic wastage allowance. The few extra tiles you order are much cheaper than the disruption of running out.
Try our tile calculator
Calculate tiles, adhesive, grout and spacers for your project. Works with any tile size and handles multiple rooms.