Working out the number of tiles needed to fill a square metre is actually pretty simple! This is how you do it.
The mathematical formula : (100*100) / (30*60)
To work out how many tiles you need per m2 (sqm), multiply the Width and Height of a square metre in centimetres (100*100), this will give you 10,000. Do the same with the tile, for our example you should have the results below:
100 x 100 cm = 10,000
30 x 60 cm = 1800
Divide the the square metre by the tile
10,000 ÷ 1800 = 5.55555556
Round that number up and you have 5.55 Tiles per square meter!