How does a 3 foot by 3 foot tile cover 8.78 sqft and if I need to cover a 6 by 6 foot room why is the recommended QTY 9? Please explain you maths and please show your work.

Our Tatami tiles seem to cover marginally different square footage than you might think because of their interlocking sides, though the full tile size is 3' x 3' when measured. When tiles are interlocked you can see that they are somewhat overlapped, this causes the recommended quantities to increase in our calculator because it is trying to make sure you have enough tiles to be flush with whatever measurements you provide.