It depends on how high you want to raise your floor.
Tile over cement board.
A better solution is to prepare and resurface the concrete slab so that it can accept thin set adhesive or a mortar base onto which to lay tile.
But doing so is a very laborious time consuming process that is likely more trouble than it is worth.
This will tell you how much tile you should buy for the job.
Installing tile directly on concrete.
In order to install tile over cement board you will need to first measure the room.
Step 1 measure the area.
Our project tiling the walls around a standard 5 ft.
For highly wet areas such as showers and bathtub surrounds cement board typically is attached directly over the wall studs and the studs may be covered with an intervening moisture membrane.
Use the tape measure and get the dimensions of the space.
Tub to a height of 6 ft requires four 3 x 5 ft.
There is no need to install backer board on a concrete substrate ceramic tile can be applied right over concrete provided the surface is flat smooth and free of significant cracks.
Thick cement board spans studs spaced 16 in.
Yet this application does make sense since concrete is heavy solid and is typically thought of as an unbending uncompromising material.
And 4 x 4 ft are available but you may have to contact a tile supplier to find them.
Other sizes like 3 x 4 ft 3 x 6 ft.
Ceramic and porcelain tile are so frequently installed at or above grade level on a cement board underlayment or directly on plywood that it almost seems novel to install tile directly on concrete.
Laying a cement board under a tile when using a cement backer board you can go with whether a inch thickness or a inch thickness.
Technically cement board can be laid over a concrete slab as the base for a tile installation.