Tile, boxes, and the thinset underneath — the three numbers that get a tile job home in one trip.
Job details
sq ft
Boxes to buy
—
Individual tiles—
Tile needed (with waste)—
Thinset (50 lb bags @ ~85 sq ft)—
Large-format tile (any side over 15 in) wants a larger trowel and often back-buttering, which drops thinset coverage toward 60–70 sq ft per bag — buy one extra.
The three-part tile order
Tile math has layers: the tile itself (with waste for cuts and breakage), the boxes it ships in, and the thinset mortar that bonds it. Ten percent waste handles a straight grid in a normal room; offsets, diagonals, and small rooms full of cuts deserve fifteen.
A 120 sq ft floor in 12 × 24 tile with 10% waste: 132 sq ft — 9 boxes at 15 sq ft, 66 tiles, and 2 bags of thinset. Ordering by boxes matters because dye lots vary: tiles from a later production run can be visibly off-shade, so get it all at once and check lot numbers match.
What the pros sweat
Flat substrate first — thinset fills tiny voids, not dips. Modern offset patterns with plank tile use a one-third stagger, not 50%, to avoid lippage at the bowed centers of long tiles. And dry-lay a row both directions before mixing anything: shifting the layout two inches can turn slivers at the wall into clean half-tiles.
Frequently asked questions
How much extra tile should I order?
10% for straightforward grid layouts, 15% for diagonal or offset patterns and rooms with lots of cuts. Also keep a few spares after the job — matching a discontinued tile years later is a lottery.
How much area does a bag of thinset cover?
A 50-lb bag covers roughly 75–95 sq ft with a 1/4-inch trowel — call it 85 for planning. Large-format tile with bigger trowels and back-buttering can cut that nearly in half.
What is tile lippage and how do I avoid it?
Lippage is when adjacent tile edges sit at different heights. Prevent it with a flat substrate, a one-third offset on plank tiles, leveling clips on large formats, and proper thinset coverage under the whole tile.