For the slightly mathematically challenged among you we have performed a worked example of the calculations needed to work out tile quantities. You can follow this and use it as a model to work out the quantity of tiles you need for your own room.
Our room is shown below. Its width (A) = 3.3m, Its depth (B) = 4.1m, Its height (C) = 2.5m
To work out the floor area you multiply A by B, 3.3 x 4.1 = 13.53m²
We then need to add 5% to 10% to this to account for wastage created when the tiles are cut to shape. Add 5% for small tiles and 10% for large tiles. To add 5% multiply your floor area by 1.05, to add 10% multiply by 1.10.
So in our example we already worked out our floor area was 13.53².
To add 5% 13.53 x 1.05 = 14.21m²
To add 10% 13.53 x 1.10 = 14.88m²
Once you have chosen your tiles you need to look at the packaging and find out how many square meters are in a box.
In our example the tiles come in boxes that contain 1.44m2. So we need to work out how many boxes we need to buy. To do this divide the floor area plus wastage by the box size. In our example we worked out we needed 14.88m² of tiles including our 10% of wastage. So the number of boxes of tiles we need is;
14.88/1.44 = 10.3
You can decide to be stingy and buy 10 boxes or play it safe and go for 11.
The same principles are applied to the walls. First work out the total wall area, which is the height (C) multiplied by the floor width (A) and depth (B).
We have four walls, two A’s and two B’s. In our example this is 3.3+3.3+4.1+4.1 = 14.8.
Then we need to multiply this by the room height to give us the total wall area;
14.8 x 2.5 = 37m²
One extra thing to think about are the doors and windows – we are not going to tile over these so we should reduce the 37m² by the area of the doors and windows. For each door and window multiply it’s height by it’s width to calculate it’s area.
In our example our door is 73cm wide and 2.1m high. Make sure all your measurements are in meters first, 73cm is 0.73m. The door area is therefore 0.73 x 2.1 = 1.53m²
Let’s say we worked out that the windows have an area of 0.8m² and 1.2m².
So the total area of the doors and two windows is 1.53 + 0.8 + 1.2 = 3.53m².
Subtract the area of the door and windows from the total wall area; 37 – 3.53 = 33.47m²
We then add 5% for wastage (as we are using small tiles); 33.47 x 1.05 = 35.14m².
Our tiles come in boxes of 1.22m2 so to work out how many boxes we need to buy; 35.14/1.22 = 28.8.
So we buy 29 boxes.