Tile, Thinset & Grout Takeoff
Tile pieces and boxes for your tile size, thinset bags sized by notch, and grout computed from the joint geometry instead of a rule of thumb.
Thinset coverage is set by the notch, not the tile: a 1/4 in square notch holds about 40 sq ft per 50 lb bag, a 1/2 in U-notch about 22. Grout is joint volume: width x depth x area.
How the math works
- Pieces: tile area = width × length ÷ 144. Buy (area × (1 + waste)) ÷ piece area, rounded up. Waste is 10% for open floors, 15 to 20% for small bathrooms with many cuts.
- Boxes: tile is sold by the box and returns are per box, so boxes = bought sq ft ÷ box coverage, rounded up. Mix boxes from a single dye lot.
- Thinset: coverage per 50 lb bag is fixed by the notch: 1/4 in square notch 40 sq ft, 3/8 in 30, 1/2 in U-notch 22, 3/4 in 15. Larger notches exist to keep full coverage on big tiles, not to use more thinset.
- Grout: joint volume = area × joint width × joint depth (tile thickness). Fresh grout is about 112 lb per cubic foot, which is where the pounds come from. Sanded grout for joints 1/8 in and wider, unsanded for narrower.
- Cost: tile per sq ft bought, thinset at $17/bag, grout at $16/bag. Add thinset at 35 sq ft per 25 lb bag when you buy the smaller bag.
How many bags of thinset for 120 sq ft of tile?
Three 50 lb bags with a 1/4 in square notch (132 sq ft bought / 40 sq ft per bag = 3.3, rounded to 4 with the 10% waste already in it), six bags of the 25 lb size. Large-format tile with a 1/2 in notch takes six 50 lb bags.
What notched trowel for 12x12 tile?
A 1/4 in square notch. Once a tile is over 16 in, go to a 1/2 in U-notch so the ribs collapse into full coverage when the tile is back-beveled and flipped.
How much grout for 120 sq ft of 12x12 tile?
At a 1/8 in joint and 3/8 in tile thickness: 132 x 0.0104 x 0.031 x 112 = about 5 lb, so one 25 lb bag covers 120 sq ft several times over. Buying by the tube (unsanded scribe) avoids wasting a bag.