How Many Tiles Do I Need for a 5x8 Bathroom?

Tile counts start from two areas: the room and one tile. The room is simple — 5 ft × 8 ft = 40 ft². The tile has to be converted from inches: multiply its two dimensions in inches and divide by 144 to get square feet. A 12×12 tile is 144 ÷ 144 = 1.0 ft². A 12×24 is 288 ÷ 144 = 2.0 ft². A 6×24 plank is 1.0 ft². A 4×4 is 0.111 ft².

Divide room area by tile area for the base count. Forty square feet in 12×12 tile is 40 tiles; in 12×24 it is 20 tiles; in 4×4 it is 360 tiles. Grout joints are thin enough that most estimators ignore them for counting purposes, which conveniently builds in a small cushion.

Add waste based on layout, not on room size. A straight stack or grid layout needs 10%. A diagonal, herringbone or offset-brick layout needs 15% because every perimeter tile is cut at an angle. Large-format tile in a small bathroom also runs higher because a single bad cut wastes 2 ft². For the 5×8 floor in 12×12 tile at 10%, order 44 tiles — usually two boxes of 24.

Do not forget the walls if you are tiling them. A standard tub surround is roughly 60 ft² of wall for a 5 ft tub with tile to 6 ft, and a shower niche, curb and bench each add their own small areas plus a lot of cuts.

Setting materials scale with the tile size. Thin-set coverage runs about 95 ft² per 50 lb bag with a 1/4 in square-notch trowel for small tile, dropping to 60–70 ft² with the 1/2 in trowel large-format tile requires. Grout for 12×12 tile with 1/8 in joints covers roughly 100 ft² per 25 lb bag; narrow joints stretch it, and large 1/2 in joints on stone can cut it in half. Add an uncoupling or waterproofing membrane on bathroom floors — it is sold by the roll in square feet and is the cheapest insurance on the job.