How many bags of thinset do you need?
Enter the room and tile size. We suggest a trowel notch and work out how many 50 lb bags of thinset mortar to buy.
Thinset coverage by trowel notch
Square feet per 50 lb bag, from manufacturer coverage charts. We size your bag count on the low end.
| Trowel notch | Sq ft per 50 lb bag | Typical use |
|---|---|---|
| 1/4" × 1/4" square notch | 85–95 | Tile up to about 8" |
| 1/4" × 3/8" square notch | 60–67 | Tile about 8" to 15" |
| 1/2" × 1/2" square notch | 30–40 | Large-format tile, 15" and up |
Getting full coverage
- Comb the mortar in straight lines, not swirls, so air can escape when you set the tile.
- Lift a tile now and then: the back should be fully covered. If not, go up a notch size.
- Back-butter large-format tile and planks.
- Flatten the floor first; mortar isn’t a leveller. Then hold the edges flush with leveling clips while it cures.
Frequently asked questions
How much does a 50 lb bag of thinset cover?
It depends mostly on the trowel notch. Manufacturer charts give about 85–95 sq ft with a 1/4" square notch, 60–67 sq ft with a 1/4" × 3/8" notch, and 30–40 sq ft with a 1/2" square notch. Back-buttering large tile uses more.
What trowel size should I use?
As a starting point: a 1/4" square notch for tile up to about 8", 1/4" × 3/8" for tile about 8" to 15", and 1/2" square for large-format tile. Then lift a tile and check the back is fully covered; go up a size if it isn't.
Do I need to back-butter large tile?
Yes. Large-format tile and planks should be back-buttered with a thin skim of mortar on the back, so the tile gets full coverage. It uses more mortar, so plan on an extra bag.
Can leveling clips make up for thin mortar coverage?
No. Clips hold neighbouring edges flush while the mortar cures; they can't fill voids. Full coverage under the tile still matters.
Now count your clips.
The clip calculator counts leveling clips and wedges for the same room, and adds them to your order.